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* aio-posix: split poll check from ready handlerStefan Hajnoczi2022-01-121-6/+10
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Adaptive polling measures the execution time of the polling check plus handlers called when a polled event becomes ready. Handlers can take a significant amount of time, making it look like polling was running for a long time when in fact the event handler was running for a long time. For example, on Linux the io_submit(2) syscall invoked when a virtio-blk device's virtqueue becomes ready can take 10s of microseconds. This can exceed the default polling interval (32 microseconds) and cause adaptive polling to stop polling. By excluding the handler's execution time from the polling check we make the adaptive polling calculation more accurate. As a result, the event loop now stays in polling mode where previously it would have fallen back to file descriptor monitoring. The following data was collected with virtio-blk num-queues=2 event_idx=off using an IOThread. Before: 168k IOPS, IOThread syscalls: 9837.115 ( 0.020 ms): IO iothread1/620155 io_submit(ctx_id: 140512552468480, nr: 16, iocbpp: 0x7fcb9f937db0) = 16 9837.158 ( 0.002 ms): IO iothread1/620155 write(fd: 103, buf: 0x556a2ef71b88, count: 8) = 8 9837.161 ( 0.001 ms): IO iothread1/620155 write(fd: 104, buf: 0x556a2ef71b88, count: 8) = 8 9837.163 ( 0.001 ms): IO iothread1/620155 ppoll(ufds: 0x7fcb90002800, nfds: 4, tsp: 0x7fcb9f1342d0, sigsetsize: 8) = 3 9837.164 ( 0.001 ms): IO iothread1/620155 read(fd: 107, buf: 0x7fcb9f939cc0, count: 512) = 8 9837.174 ( 0.001 ms): IO iothread1/620155 read(fd: 105, buf: 0x7fcb9f939cc0, count: 512) = 8 9837.176 ( 0.001 ms): IO iothread1/620155 read(fd: 106, buf: 0x7fcb9f939cc0, count: 512) = 8 9837.209 ( 0.035 ms): IO iothread1/620155 io_submit(ctx_id: 140512552468480, nr: 32, iocbpp: 0x7fca7d0cebe0) = 32 174k IOPS (+3.6%), IOThread syscalls: 9809.566 ( 0.036 ms): IO iothread1/623061 io_submit(ctx_id: 140539805028352, nr: 32, iocbpp: 0x7fd0cdd62be0) = 32 9809.625 ( 0.001 ms): IO iothread1/623061 write(fd: 103, buf: 0x5647cfba5f58, count: 8) = 8 9809.627 ( 0.002 ms): IO iothread1/623061 write(fd: 104, buf: 0x5647cfba5f58, count: 8) = 8 9809.663 ( 0.036 ms): IO iothread1/623061 io_submit(ctx_id: 140539805028352, nr: 32, iocbpp: 0x7fd0d0388b50) = 32 Notice that ppoll(2) and eventfd read(2) syscalls are eliminated because the IOThread stays in polling mode instead of falling back to file descriptor monitoring. As usual, polling is not implemented on Windows so this patch ignores the new io_poll_read() callback in aio-win32.c. Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com> Reviewed-by: Stefano Garzarella <sgarzare@redhat.com> Message-id: 20211207132336.36627-2-stefanha@redhat.com [Fixed up aio_set_event_notifier() calls in tests/unit/test-fdmon-epoll.c added after this series was queued. --Stefan] Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
* linux-aio: add `dev_max_batch` parameter to laio_io_unplug()Stefano Garzarella2021-11-021-3/+5
| | | | | | | | | | | | | | | Between the submission of a request and the unplug, other devices with larger limits may have been queued new requests without flushing the batch. Using the new `dev_max_batch` parameter, laio_io_unplug() can check if the batch exceeds the device limit to flush the current batch. Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com> Reviewed-by: Kevin Wolf <kwolf@redhat.com> Signed-off-by: Stefano Garzarella <sgarzare@redhat.com> Message-Id: <20211026162346.253081-4-sgarzare@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
* linux-aio: add `dev_max_batch` parameter to laio_co_submit()Stefano Garzarella2021-11-021-8/+22
| | | | | | | | | | | | | | | | This new parameter can be used by block devices to limit the Linux AIO batch size more than the limit set by the AIO context. file-posix backend supports this, passing its `aio-max-batch` option previously added. Add an helper function to calculate the maximum batch size. Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com> Reviewed-by: Kevin Wolf <kwolf@redhat.com> Signed-off-by: Stefano Garzarella <sgarzare@redhat.com> Message-Id: <20211026162346.253081-3-sgarzare@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
* linux-aio: limit the batch size using `aio-max-batch` parameterStefano Garzarella2021-07-211-1/+8
| | | | | | | | | | | | | | | | | | | | | | | | | | | | When there are multiple queues attached to the same AIO context, some requests may experience high latency, since in the worst case the AIO engine queue is only flushed when it is full (MAX_EVENTS) or there are no more queues plugged. Commit 2558cb8dd4 ("linux-aio: increasing MAX_EVENTS to a larger hardcoded value") changed MAX_EVENTS from 128 to 1024, to increase the number of in-flight requests. But this change also increased the potential maximum batch to 1024 elements. When there is a single queue attached to the AIO context, the issue is mitigated from laio_io_unplug() that will flush the queue every time is invoked since there can't be others queue plugged. Let's use the new `aio-max-batch` IOThread parameter to mitigate this issue, limiting the number of requests in a batch. We also define a default value (32): this value is obtained running some benchmarks and it represents a good tradeoff between the latency increase while a request is queued and the cost of the io_submit(2) system call. Signed-off-by: Stefano Garzarella <sgarzare@redhat.com> Message-id: 20210721094211.69853-4-sgarzare@redhat.com Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
* misc: Replace zero-length arrays with flexible array member (automatic)Philippe Mathieu-Daudé2020-03-161-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Description copied from Linux kernel commit from Gustavo A. R. Silva (see [3]): --v-- description start --v-- The current codebase makes use of the zero-length array language extension to the C90 standard, but the preferred mechanism to declare variable-length types such as these ones is a flexible array member [1], introduced in C99: struct foo { int stuff; struct boo array[]; }; By making use of the mechanism above, we will get a compiler warning in case the flexible array does not occur last in the structure, which will help us prevent some kind of undefined behavior bugs from being unadvertenly introduced [2] to the Linux codebase from now on. --^-- description end --^-- Do the similar housekeeping in the QEMU codebase (which uses C99 since commit 7be41675f7cb). All these instances of code were found with the help of the following Coccinelle script: @@ identifier s, m, a; type t, T; @@ struct s { ... t m; - T a[0]; + T a[]; }; @@ identifier s, m, a; type t, T; @@ struct s { ... t m; - T a[0]; + T a[]; } QEMU_PACKED; [1] https://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html [2] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=76497732932f [3] https://git.kernel.org/pub/scm/linux/kernel/git/gustavoars/linux.git/commit/?id=17642a2fbd2c1 Inspired-by: Gustavo A. R. Silva <gustavo@embeddedor.com> Reviewed-by: David Hildenbrand <david@redhat.com> Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
* linux-aio: increasing MAX_EVENTS to a larger hardcoded valueWangyong2020-01-131-1/+1
| | | | | | | | | | | | | | | | Since commit 6040aedddb5f474a9c2304b6a432a652d82b3d3c "virtio-blk: make queue size configurable",if the user set the queue size to more than 128 ,it will not take effect. That's because linux aio's maximum outstanding requests at a time is always less than or equal to 128. This patch simply increase MAX_EVENTS to a larger hardcoded value of 1024 as a shortterm fix. Signed-off-by: wangyong <wang.yongD@h3c.com> Message-id: faa5781afd354a96a0be152b288f636f@h3c.com Message-Id: <faa5781afd354a96a0be152b288f636f@h3c.com> Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
* Include qemu-common.h exactly where neededMarkus Armbruster2019-06-121-1/+0Star
| | | | | | | | | | | | | | | | No header includes qemu-common.h after this commit, as prescribed by qemu-common.h's file comment. Signed-off-by: Markus Armbruster <armbru@redhat.com> Message-Id: <20190523143508.25387-5-armbru@redhat.com> [Rebased with conflicts resolved automatically, except for include/hw/arm/xlnx-zynqmp.h hw/arm/nrf51_soc.c hw/arm/msf2-soc.c block/qcow2-refcount.c block/qcow2-cluster.c block/qcow2-cache.c target/arm/cpu.h target/lm32/cpu.h target/m68k/cpu.h target/mips/cpu.h target/moxie/cpu.h target/nios2/cpu.h target/openrisc/cpu.h target/riscv/cpu.h target/tilegx/cpu.h target/tricore/cpu.h target/unicore32/cpu.h target/xtensa/cpu.h; bsd-user/main.c and net/tap-bsd.c fixed up]
* block/linux-aio: Drop unused BlockAIOCB submission methodJulia Suvorova2019-06-041-62/+10Star
| | | | | | | | | | | Callback-based laio_submit() and laio_cancel() were left after rewriting Linux AIO backend to coroutines in hope that they would be used in other code that could bypass coroutines. They can be safely removed because they have not been used since that time. Signed-off-by: Julia Suvorova <jusual@mail.ru> Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
* avoid TABs in files that only contain a fewPaolo Bonzini2019-01-111-2/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Most files that have TABs only contain a handful of them. Change them to spaces so that we don't confuse people. disas, standard-headers, linux-headers and libdecnumber are imported from other projects and probably should be exempted from the check. Outside those, after this patch the following files still contain both 8-space and TAB sequences at the beginning of the line. Many of them have a majority of TABs, or were initially committed with all tabs. bsd-user/i386/target_syscall.h bsd-user/x86_64/target_syscall.h crypto/aes.c hw/audio/fmopl.c hw/audio/fmopl.h hw/block/tc58128.c hw/display/cirrus_vga.c hw/display/xenfb.c hw/dma/etraxfs_dma.c hw/intc/sh_intc.c hw/misc/mst_fpga.c hw/net/pcnet.c hw/sh4/sh7750.c hw/timer/m48t59.c hw/timer/sh_timer.c include/crypto/aes.h include/disas/bfd.h include/hw/sh4/sh.h libdecnumber/decNumber.c linux-headers/asm-generic/unistd.h linux-headers/linux/kvm.h linux-user/alpha/target_syscall.h linux-user/arm/nwfpe/double_cpdo.c linux-user/arm/nwfpe/fpa11_cpdt.c linux-user/arm/nwfpe/fpa11_cprt.c linux-user/arm/nwfpe/fpa11.h linux-user/flat.h linux-user/flatload.c linux-user/i386/target_syscall.h linux-user/ppc/target_syscall.h linux-user/sparc/target_syscall.h linux-user/syscall.c linux-user/syscall_defs.h linux-user/x86_64/target_syscall.h slirp/cksum.c slirp/if.c slirp/ip.h slirp/ip_icmp.c slirp/ip_icmp.h slirp/ip_input.c slirp/ip_output.c slirp/mbuf.c slirp/misc.c slirp/sbuf.c slirp/socket.c slirp/socket.h slirp/tcp_input.c slirp/tcpip.h slirp/tcp_output.c slirp/tcp_subr.c slirp/tcp_timer.c slirp/tftp.c slirp/udp.c slirp/udp.h target/cris/cpu.h target/cris/mmu.c target/cris/op_helper.c target/sh4/helper.c target/sh4/op_helper.c target/sh4/translate.c tcg/sparc/tcg-target.inc.c tests/tcg/cris/check_addo.c tests/tcg/cris/check_moveq.c tests/tcg/cris/check_swap.c tests/tcg/multiarch/test-mmap.c ui/vnc-enc-hextile-template.h ui/vnc-enc-zywrle.h util/envlist.c util/readline.c The following have only TABs: bsd-user/i386/target_signal.h bsd-user/sparc64/target_signal.h bsd-user/sparc64/target_syscall.h bsd-user/sparc/target_signal.h bsd-user/sparc/target_syscall.h bsd-user/x86_64/target_signal.h crypto/desrfb.c hw/audio/intel-hda-defs.h hw/core/uboot_image.h hw/sh4/sh7750_regnames.c hw/sh4/sh7750_regs.h include/hw/cris/etraxfs_dma.h linux-user/alpha/termbits.h linux-user/arm/nwfpe/fpopcode.h linux-user/arm/nwfpe/fpsr.h linux-user/arm/syscall_nr.h linux-user/arm/target_signal.h linux-user/cris/target_signal.h linux-user/i386/target_signal.h linux-user/linux_loop.h linux-user/m68k/target_signal.h linux-user/microblaze/target_signal.h linux-user/mips64/target_signal.h linux-user/mips/target_signal.h linux-user/mips/target_syscall.h linux-user/mips/termbits.h linux-user/ppc/target_signal.h linux-user/sh4/target_signal.h linux-user/sh4/termbits.h linux-user/sparc64/target_syscall.h linux-user/sparc/target_signal.h linux-user/x86_64/target_signal.h linux-user/x86_64/termbits.h pc-bios/optionrom/optionrom.h slirp/mbuf.h slirp/misc.h slirp/sbuf.h slirp/tcp.h slirp/tcp_timer.h slirp/tcp_var.h target/i386/svm.h target/sparc/asi.h target/xtensa/core-dc232b/xtensa-modules.inc.c target/xtensa/core-dc233c/xtensa-modules.inc.c target/xtensa/core-de212/core-isa.h target/xtensa/core-de212/xtensa-modules.inc.c target/xtensa/core-fsf/xtensa-modules.inc.c target/xtensa/core-sample_controller/core-isa.h target/xtensa/core-sample_controller/xtensa-modules.inc.c target/xtensa/core-test_kc705_be/core-isa.h target/xtensa/core-test_kc705_be/xtensa-modules.inc.c tests/tcg/cris/check_abs.c tests/tcg/cris/check_addc.c tests/tcg/cris/check_addcm.c tests/tcg/cris/check_addoq.c tests/tcg/cris/check_bound.c tests/tcg/cris/check_ftag.c tests/tcg/cris/check_int64.c tests/tcg/cris/check_lz.c tests/tcg/cris/check_openpf5.c tests/tcg/cris/check_sigalrm.c tests/tcg/cris/crisutils.h tests/tcg/cris/sys.c tests/tcg/i386/test-i386-ssse3.c ui/vgafont.h Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Message-Id: <20181213223737.11793-3-pbonzini@redhat.com> Reviewed-by: Aleksandar Markovic <amarkovic@wavecomp.com> Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com> Reviewed-by: Wainer dos Santos Moschetta <wainersm@redhat.com> Acked-by: Richard Henderson <richard.henderson@linaro.org> Acked-by: Eric Blake <eblake@redhat.com> Acked-by: David Gibson <david@gibson.dropbear.id.au> Reviewed-by: Stefan Markovic <smarkovic@wavecomp.com> Reviewed-by: Michael S. Tsirkin <mst@redhat.com> Reviewed-by: Alex Bennée <alex.bennee@linaro.org> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
* block/linux-aio: acquire AioContext before qemu_laio_process_completionsSergio Lopez2018-09-251-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | In qemu_laio_process_completions_and_submit, the AioContext is acquired before the ioq_submit iteration and after qemu_laio_process_completions, but the latter is not thread safe either. This change avoids a number of random crashes when the Main Thread and an IO Thread collide processing completions for the same AioContext. This is an example of such crash: - The IO Thread is trying to acquire the AioContext at aio_co_enter, which evidences that it didn't lock it before: Thread 3 (Thread 0x7fdfd8bd8700 (LWP 36743)): #0 0x00007fdfe0dd542d in __lll_lock_wait () at ../nptl/sysdeps/unix/sysv/linux/x86_64/lowlevellock.S:135 #1 0x00007fdfe0dd0de6 in _L_lock_870 () at /lib64/libpthread.so.0 #2 0x00007fdfe0dd0cdf in __GI___pthread_mutex_lock (mutex=mutex@entry=0x5631fde0e6c0) at ../nptl/pthread_mutex_lock.c:114 #3 0x00005631fc0603a7 in qemu_mutex_lock_impl (mutex=0x5631fde0e6c0, file=0x5631fc23520f "util/async.c", line=511) at util/qemu-thread-posix.c:66 #4 0x00005631fc05b558 in aio_co_enter (ctx=0x5631fde0e660, co=0x7fdfcc0c2b40) at util/async.c:493 #5 0x00005631fc05b5ac in aio_co_wake (co=<optimized out>) at util/async.c:478 #6 0x00005631fbfc51ad in qemu_laio_process_completion (laiocb=<optimized out>) at block/linux-aio.c:104 #7 0x00005631fbfc523c in qemu_laio_process_completions (s=s@entry=0x7fdfc0297670) at block/linux-aio.c:222 #8 0x00005631fbfc5499 in qemu_laio_process_completions_and_submit (s=0x7fdfc0297670) at block/linux-aio.c:237 #9 0x00005631fc05d978 in aio_dispatch_handlers (ctx=ctx@entry=0x5631fde0e660) at util/aio-posix.c:406 #10 0x00005631fc05e3ea in aio_poll (ctx=0x5631fde0e660, blocking=blocking@entry=true) at util/aio-posix.c:693 #11 0x00005631fbd7ad96 in iothread_run (opaque=0x5631fde0e1c0) at iothread.c:64 #12 0x00007fdfe0dcee25 in start_thread (arg=0x7fdfd8bd8700) at pthread_create.c:308 #13 0x00007fdfe0afc34d in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:113 - The Main Thread is also processing completions from the same AioContext, and crashes due to failed assertion at util/iov.c:78: Thread 1 (Thread 0x7fdfeb5eac80 (LWP 36740)): #0 0x00007fdfe0a391f7 in __GI_raise (sig=sig@entry=6) at ../nptl/sysdeps/unix/sysv/linux/raise.c:56 #1 0x00007fdfe0a3a8e8 in __GI_abort () at abort.c:90 #2 0x00007fdfe0a32266 in __assert_fail_base (fmt=0x7fdfe0b84e68 "%s%s%s:%u: %s%sAssertion `%s' failed.\n%n", assertion=assertion@entry=0x5631fc238ccb "offset == 0", file=file@entry=0x5631fc23698e "util/iov.c", line=line@entry=78, function=function@entry=0x5631fc236adc <__PRETTY_FUNCTION__.15220> "iov_memset") at assert.c:92 #3 0x00007fdfe0a32312 in __GI___assert_fail (assertion=assertion@entry=0x5631fc238ccb "offset == 0", file=file@entry=0x5631fc23698e "util/iov.c", line=line@entry=78, function=function@entry=0x5631fc236adc <__PRETTY_FUNCTION__.15220> "iov_memset") at assert.c:101 #4 0x00005631fc065287 in iov_memset (iov=<optimized out>, iov_cnt=<optimized out>, offset=<optimized out>, offset@entry=65536, fillc=fillc@entry=0, bytes=15515191315812405248) at util/iov.c:78 #5 0x00005631fc065a63 in qemu_iovec_memset (qiov=<optimized out>, offset=offset@entry=65536, fillc=fillc@entry=0, bytes=<optimized out>) at util/iov.c:410 #6 0x00005631fbfc5178 in qemu_laio_process_completion (laiocb=0x7fdd920df630) at block/linux-aio.c:88 #7 0x00005631fbfc523c in qemu_laio_process_completions (s=s@entry=0x7fdfc0297670) at block/linux-aio.c:222 #8 0x00005631fbfc5499 in qemu_laio_process_completions_and_submit (s=0x7fdfc0297670) at block/linux-aio.c:237 #9 0x00005631fbfc54ed in qemu_laio_poll_cb (opaque=<optimized out>) at block/linux-aio.c:272 #10 0x00005631fc05d85e in run_poll_handlers_once (ctx=ctx@entry=0x5631fde0e660) at util/aio-posix.c:497 #11 0x00005631fc05e2ca in aio_poll (blocking=false, ctx=0x5631fde0e660) at util/aio-posix.c:574 #12 0x00005631fc05e2ca in aio_poll (ctx=0x5631fde0e660, blocking=blocking@entry=false) at util/aio-posix.c:604 #13 0x00005631fbfcb8a3 in bdrv_do_drained_begin (ignore_parent=<optimized out>, recursive=<optimized out>, bs=<optimized out>) at block/io.c:273 #14 0x00005631fbfcb8a3 in bdrv_do_drained_begin (bs=0x5631fe8b6200, recursive=<optimized out>, parent=0x0, ignore_bds_parents=<optimized out>, poll=<optimized out>) at block/io.c:390 #15 0x00005631fbfbcd2e in blk_drain (blk=0x5631fe83ac80) at block/block-backend.c:1590 #16 0x00005631fbfbe138 in blk_remove_bs (blk=blk@entry=0x5631fe83ac80) at block/block-backend.c:774 #17 0x00005631fbfbe3d6 in blk_unref (blk=0x5631fe83ac80) at block/block-backend.c:401 #18 0x00005631fbfbe3d6 in blk_unref (blk=0x5631fe83ac80) at block/block-backend.c:449 #19 0x00005631fbfc9a69 in commit_complete (job=0x5631fe8b94b0, opaque=0x7fdfcc1bb080) at block/commit.c:92 #20 0x00005631fbf7d662 in job_defer_to_main_loop_bh (opaque=0x7fdfcc1b4560) at job.c:973 #21 0x00005631fc05ad41 in aio_bh_poll (bh=0x7fdfcc01ad90) at util/async.c:90 #22 0x00005631fc05ad41 in aio_bh_poll (ctx=ctx@entry=0x5631fddffdb0) at util/async.c:118 #23 0x00005631fc05e210 in aio_dispatch (ctx=0x5631fddffdb0) at util/aio-posix.c:436 #24 0x00005631fc05ac1e in aio_ctx_dispatch (source=<optimized out>, callback=<optimized out>, user_data=<optimized out>) at util/async.c:261 #25 0x00007fdfeaae44c9 in g_main_context_dispatch (context=0x5631fde00140) at gmain.c:3201 #26 0x00007fdfeaae44c9 in g_main_context_dispatch (context=context@entry=0x5631fde00140) at gmain.c:3854 #27 0x00005631fc05d503 in main_loop_wait () at util/main-loop.c:215 #28 0x00005631fc05d503 in main_loop_wait (timeout=<optimized out>) at util/main-loop.c:238 #29 0x00005631fc05d503 in main_loop_wait (nonblocking=nonblocking@entry=0) at util/main-loop.c:497 #30 0x00005631fbd81412 in main_loop () at vl.c:1866 #31 0x00005631fbc18ff3 in main (argc=<optimized out>, argv=<optimized out>, envp=<optimized out>) at vl.c:4647 - A closer examination shows that s->io_q.in_flight appears to have gone backwards: (gdb) frame 7 #7 0x00005631fbfc523c in qemu_laio_process_completions (s=s@entry=0x7fdfc0297670) at block/linux-aio.c:222 222 qemu_laio_process_completion(laiocb); (gdb) p s $2 = (LinuxAioState *) 0x7fdfc0297670 (gdb) p *s $3 = {aio_context = 0x5631fde0e660, ctx = 0x7fdfeb43b000, e = {rfd = 33, wfd = 33}, io_q = {plugged = 0, in_queue = 0, in_flight = 4294967280, blocked = false, pending = {sqh_first = 0x0, sqh_last = 0x7fdfc0297698}}, completion_bh = 0x7fdfc0280ef0, event_idx = 21, event_max = 241} (gdb) p/x s->io_q.in_flight $4 = 0xfffffff0 Signed-off-by: Sergio Lopez <slp@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
* linux-aio: properly bubble up errors from initializationNishanth Aravamudan2018-06-271-3/+9
| | | | | | | | | | | | | | | | | | | | | | | | laio_init() can fail for a couple of reasons, which will lead to a NULL pointer dereference in laio_attach_aio_context(). To solve this, add a aio_setup_linux_aio() function which is called early in raw_open_common. If this fails, propagate the error up. The signature of aio_get_linux_aio() was not modified, because it seems preferable to return the actual errno from the possible failing initialization calls. Additionally, when the AioContext changes, we need to associate a LinuxAioState with the new AioContext. Use the bdrv_attach_aio_context callback and call the new aio_setup_linux_aio(), which will allocate a new AioContext if needed, and return errors on failures. If it fails for any reason, fallback to threaded AIO with an error message, as the device is already in-use by the guest. Add an assert that aio_get_linux_aio() cannot return NULL. Signed-off-by: Nishanth Aravamudan <naravamudan@digitalocean.com> Message-id: 20180622193700.6523-1-naravamudan@digitalocean.com Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
* block: explicitly acquire aiocontext in aio callbacks that need itPaolo Bonzini2017-02-211-4/+1Star
| | | | | | | | | Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Reviewed-by: Fam Zheng <famz@redhat.com> Reviewed-by: Daniel P. Berrange <berrange@redhat.com> Message-id: 20170213135235.12274-16-pbonzini@redhat.com Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
* block: explicitly acquire aiocontext in bottom halves that need itPaolo Bonzini2017-02-211-6/+9
| | | | | | | | | Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Reviewed-by: Fam Zheng <famz@redhat.com> Reviewed-by: Daniel P. Berrange <berrange@redhat.com> Message-id: 20170213135235.12274-15-pbonzini@redhat.com Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
* block: explicitly acquire aiocontext in callbacks that need itPaolo Bonzini2017-02-211-0/+4
| | | | | | | | | | | | This covers both file descriptor callbacks and polling callbacks, since they execute related code. Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Reviewed-by: Fam Zheng <famz@redhat.com> Reviewed-by: Daniel P. Berrange <berrange@redhat.com> Message-id: 20170213135235.12274-14-pbonzini@redhat.com Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
* linux-aio: poll ring for completionsStefan Hajnoczi2017-01-031-1/+16
| | | | | | | | | | | | | The Linux AIO userspace ABI includes a ring that is shared with the kernel. This allows userspace programs to process completions without system calls. Add an AioContext poll handler to check for completions in the ring. Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com> Reviewed-by: Paolo Bonzini <pbonzini@redhat.com> Message-id: 20161201192652.9509-6-stefanha@redhat.com Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
* aio: add AioPollFn and io_poll() interfaceStefan Hajnoczi2017-01-031-2/+2
| | | | | | | | | | | | The new AioPollFn io_poll() argument to aio_set_fd_handler() and aio_set_event_handler() is used in the next patch. Keep this code change separate due to the number of files it touches. Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com> Reviewed-by: Paolo Bonzini <pbonzini@redhat.com> Message-id: 20161201192652.9509-3-stefanha@redhat.com Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
* linux-aio: fix re-entrant completion processingStefan Hajnoczi2016-09-281-3/+6
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Commit 0ed93d84edabc7656f5c998ae1a346fe8b94ca54 ("linux-aio: process completions from ioq_submit()") added an optimization that processes completions each time ioq_submit() returns with requests in flight. This commit introduces a "Co-routine re-entered recursively" error which can be triggered with -drive format=qcow2,aio=native. Fam Zheng <famz@redhat.com>, Kevin Wolf <kwolf@redhat.com>, and I debugged the following backtrace: (gdb) bt #0 0x00007ffff0a046f5 in raise () at /lib64/libc.so.6 #1 0x00007ffff0a062fa in abort () at /lib64/libc.so.6 #2 0x0000555555ac0013 in qemu_coroutine_enter (co=0x5555583464d0) at util/qemu-coroutine.c:113 #3 0x0000555555a4b663 in qemu_laio_process_completions (s=s@entry=0x555557e2f7f0) at block/linux-aio.c:218 #4 0x0000555555a4b874 in ioq_submit (s=s@entry=0x555557e2f7f0) at block/linux-aio.c:331 #5 0x0000555555a4ba12 in laio_do_submit (fd=fd@entry=13, laiocb=laiocb@entry=0x555559d38ae0, offset=offset@entry=2932727808, type=type@entry=1) at block/linux-aio.c:383 #6 0x0000555555a4bbd3 in laio_co_submit (bs=<optimized out>, s=0x555557e2f7f0, fd=13, offset=2932727808, qiov=0x555559d38e20, type=1) at block/linux-aio.c:402 #7 0x0000555555a4fd23 in bdrv_driver_preadv (bs=bs@entry=0x55555663bcb0, offset=offset@entry=2932727808, bytes=bytes@entry=8192, qiov=qiov@entry=0x555559d38e20, flags=0) at block/io.c:804 #8 0x0000555555a52b34 in bdrv_aligned_preadv (bs=bs@entry=0x55555663bcb0, req=req@entry=0x555559d38d20, offset=offset@entry=2932727808, bytes=bytes@entry=8192, align=align@entry=512, qiov=qiov@entry=0x555559d38e20, flags=0) at block/io.c:1041 #9 0x0000555555a52db8 in bdrv_co_preadv (child=<optimized out>, offset=2932727808, bytes=8192, qiov=qiov@entry=0x555559d38e20, flags=flags@entry=0) at block/io.c:1133 #10 0x0000555555a29629 in qcow2_co_preadv (bs=0x555556635890, offset=6178725888, bytes=8192, qiov=0x555557527840, flags=<optimized out>) at block/qcow2.c:1509 #11 0x0000555555a4fd23 in bdrv_driver_preadv (bs=bs@entry=0x555556635890, offset=offset@entry=6178725888, bytes=bytes@entry=8192, qiov=qiov@entry=0x555557527840, flags=0) at block/io.c:804 #12 0x0000555555a52b34 in bdrv_aligned_preadv (bs=bs@entry=0x555556635890, req=req@entry=0x555559d39000, offset=offset@entry=6178725888, bytes=bytes@entry=8192, align=align@entry=1, qiov=qiov@entry=0x555557527840, flags=0) at block/io.c:1041 #13 0x0000555555a52db8 in bdrv_co_preadv (child=<optimized out>, offset=offset@entry=6178725888, bytes=bytes@entry=8192, qiov=qiov@entry=0x555557527840, flags=flags@entry=0) at block/io.c:1133 #14 0x0000555555a4515a in blk_co_preadv (blk=0x5555566356d0, offset=6178725888, bytes=8192, qiov=0x555557527840, flags=0) at block/block-backend.c:783 #15 0x0000555555a45266 in blk_aio_read_entry (opaque=0x5555577025e0) at block/block-backend.c:991 #16 0x0000555555ac0cfa in coroutine_trampoline (i0=<optimized out>, i1=<optimized out>) at util/coroutine-ucontext.c:78 It turned out that re-entrant ioq_submit() and completion processing between three requests caused this error. The following check is not sufficient to prevent recursively entering coroutines: if (laiocb->co != qemu_coroutine_self()) { qemu_coroutine_enter(laiocb->co); } As the following coroutine backtrace shows, not just the current coroutine (self) can be entered. There might also be other coroutines that are currently entered and transferred control due to the qcow2 lock (CoMutex): (gdb) qemu coroutine 0x5555583464d0 #0 0x0000555555ac0c90 in qemu_coroutine_switch (from_=from_@entry=0x5555583464d0, to_=to_@entry=0x5555572f9890, action=action@entry=COROUTINE_ENTER) at util/coroutine-ucontext.c:175 #1 0x0000555555abfe54 in qemu_coroutine_enter (co=0x5555572f9890) at util/qemu-coroutine.c:117 #2 0x0000555555ac031c in qemu_co_queue_run_restart (co=co@entry=0x5555583462c0) at util/qemu-coroutine-lock.c:60 #3 0x0000555555abfe5e in qemu_coroutine_enter (co=0x5555583462c0) at util/qemu-coroutine.c:119 #4 0x0000555555a4b663 in qemu_laio_process_completions (s=s@entry=0x555557e2f7f0) at block/linux-aio.c:218 #5 0x0000555555a4b874 in ioq_submit (s=s@entry=0x555557e2f7f0) at block/linux-aio.c:331 #6 0x0000555555a4ba12 in laio_do_submit (fd=fd@entry=13, laiocb=laiocb@entry=0x55555a338b40, offset=offset@entry=2911477760, type=type@entry=1) at block/linux-aio.c:383 #7 0x0000555555a4bbd3 in laio_co_submit (bs=<optimized out>, s=0x555557e2f7f0, fd=13, offset=2911477760, qiov=0x55555a338e80, type=1) at block/linux-aio.c:402 #8 0x0000555555a4fd23 in bdrv_driver_preadv (bs=bs@entry=0x55555663bcb0, offset=offset@entry=2911477760, bytes=bytes@entry=8192, qiov=qiov@entry=0x55555a338e80, flags=0) at block/io.c:804 #9 0x0000555555a52b34 in bdrv_aligned_preadv (bs=bs@entry=0x55555663bcb0, req=req@entry=0x55555a338d80, offset=offset@entry=2911477760, bytes=bytes@entry=8192, align=align@entry=512, qiov=qiov@entry=0x55555a338e80, flags=0) at block/io.c:1041 #10 0x0000555555a52db8 in bdrv_co_preadv (child=<optimized out>, offset=2911477760, bytes=8192, qiov=qiov@entry=0x55555a338e80, flags=flags@entry=0) at block/io.c:1133 #11 0x0000555555a29629 in qcow2_co_preadv (bs=0x555556635890, offset=6157475840, bytes=8192, qiov=0x5555575df720, flags=<optimized out>) at block/qcow2.c:1509 #12 0x0000555555a4fd23 in bdrv_driver_preadv (bs=bs@entry=0x555556635890, offset=offset@entry=6157475840, bytes=bytes@entry=8192, qiov=qiov@entry=0x5555575df720, flags=0) at block/io.c:804 #13 0x0000555555a52b34 in bdrv_aligned_preadv (bs=bs@entry=0x555556635890, req=req@entry=0x55555a339060, offset=offset@entry=6157475840, bytes=bytes@entry=8192, align=align@entry=1, qiov=qiov@entry=0x5555575df720, flags=0) at block/io.c:1041 #14 0x0000555555a52db8 in bdrv_co_preadv (child=<optimized out>, offset=offset@entry=6157475840, bytes=bytes@entry=8192, qiov=qiov@entry=0x5555575df720, flags=flags@entry=0) at block/io.c:1133 #15 0x0000555555a4515a in blk_co_preadv (blk=0x5555566356d0, offset=6157475840, bytes=8192, qiov=0x5555575df720, flags=0) at block/block-backend.c:783 #16 0x0000555555a45266 in blk_aio_read_entry (opaque=0x555557231aa0) at block/block-backend.c:991 #17 0x0000555555ac0cfa in coroutine_trampoline (i0=<optimized out>, i1=<optimized out>) at util/coroutine-ucontext.c:78 Use the new qemu_coroutine_entered() function instead of comparing against qemu_coroutine_self(). This is correct because: 1. If a coroutine is not entered then it must have yielded to wait for I/O completion. It is therefore safe to enter. 2. If a coroutine is entered then it must be in ioq_submit()/qemu_laio_process_completions() because otherwise it would be yielded while waiting for I/O completion. Therefore it will check laio->ret and return from ioq_submit() instead of yielding, i.e. it's guaranteed not to hang. Reported-by: Fam Zheng <famz@redhat.com> Tested-by: Fam Zheng <famz@redhat.com> Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com> Reviewed-by: Fam Zheng <famz@redhat.com> Message-id: 1474989516-18255-4-git-send-email-stefanha@redhat.com Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
* linux-aio: process completions from ioq_submit()Roman Pen2016-09-131-2/+22
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | In order to reduce completion latency it makes sense to harvest completed requests ASAP. Very fast backend device can complete requests just after submission, so it is worth trying to check ring buffer in order to peek completed requests directly after io_submit() has been called. Indeed, this patch reduces the completions latencies and increases the overall throughput, e.g. the following is the percentiles of number of completed requests at once: 1th 10th 20th 30th 40th 50th 60th 70th 80th 90th 99.99th Before 2 4 42 112 128 128 128 128 128 128 128 After 1 1 4 14 33 45 47 48 50 51 108 That means, that before the current patch is applied the ring buffer is observed as full (128 requests were consumed at once) in 60% of calls. After patch is applied the distribution of number of completed requests is "smoother" and the queue (requests in-flight) is almost never full. The fio read results are the following (write results are almost the same and are not showed here): Before ------ job: (groupid=0, jobs=8): err= 0: pid=2227: Tue Jul 19 11:29:50 2016 Description : [Emulation of Storage Server Access Pattern] read : io=54681MB, bw=1822.7MB/s, iops=179779, runt= 30001msec slat (usec): min=172, max=16883, avg=338.35, stdev=109.66 clat (usec): min=1, max=21977, avg=1051.45, stdev=299.29 lat (usec): min=317, max=22521, avg=1389.83, stdev=300.73 clat percentiles (usec): | 1.00th=[ 346], 5.00th=[ 596], 10.00th=[ 708], 20.00th=[ 852], | 30.00th=[ 932], 40.00th=[ 996], 50.00th=[ 1048], 60.00th=[ 1112], | 70.00th=[ 1176], 80.00th=[ 1256], 90.00th=[ 1384], 95.00th=[ 1496], | 99.00th=[ 1800], 99.50th=[ 1928], 99.90th=[ 2320], 99.95th=[ 2672], | 99.99th=[ 4704] bw (KB /s): min=205229, max=553181, per=12.50%, avg=233278.26, stdev=18383.51 After ------ job: (groupid=0, jobs=8): err= 0: pid=2220: Tue Jul 19 11:31:51 2016 Description : [Emulation of Storage Server Access Pattern] read : io=57637MB, bw=1921.2MB/s, iops=189529, runt= 30002msec slat (usec): min=169, max=20636, avg=329.61, stdev=124.18 clat (usec): min=2, max=19592, avg=988.78, stdev=251.04 lat (usec): min=381, max=21067, avg=1318.42, stdev=243.58 clat percentiles (usec): | 1.00th=[ 310], 5.00th=[ 580], 10.00th=[ 748], 20.00th=[ 876], | 30.00th=[ 908], 40.00th=[ 948], 50.00th=[ 1012], 60.00th=[ 1064], | 70.00th=[ 1080], 80.00th=[ 1128], 90.00th=[ 1224], 95.00th=[ 1288], | 99.00th=[ 1496], 99.50th=[ 1608], 99.90th=[ 1960], 99.95th=[ 2256], | 99.99th=[ 5408] bw (KB /s): min=212149, max=390160, per=12.49%, avg=245746.04, stdev=11606.75 Throughput increased from 1822MB/s to 1921MB/s, average completion latencies decreased from 1051us to 988us. Signed-off-by: Roman Pen <roman.penyaev@profitbricks.com> Message-id: 1468931263-32667-4-git-send-email-roman.penyaev@profitbricks.com Cc: Stefan Hajnoczi <stefanha@redhat.com> Cc: Paolo Bonzini <pbonzini@redhat.com> Cc: qemu-devel@nongnu.org Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
* linux-aio: split processing events functionRoman Pen2016-09-131-10/+21
| | | | | | | | | | | | | Prepare processing events function to be called from ioq_submit(), thus split function on two parts: the first harvests completed IO requests, the second submits pending requests. Signed-off-by: Roman Pen <roman.penyaev@profitbricks.com> Message-id: 1468931263-32667-3-git-send-email-roman.penyaev@profitbricks.com Cc: Stefan Hajnoczi <stefanha@redhat.com> Cc: Paolo Bonzini <pbonzini@redhat.com> Cc: qemu-devel@nongnu.org Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
* linux-aio: consume events in userspace instead of calling io_geteventsRoman Pen2016-09-131-26/+99
| | | | | | | | | | | | | | | AIO context in userspace is represented as a simple ring buffer, which can be consumed directly without entering the kernel, which obviously can bring some performance gain. QEMU does not use timeout value for waiting for events completions, so we can consume all events from userspace. Signed-off-by: Roman Pen <roman.penyaev@profitbricks.com> Message-id: 1468931263-32667-2-git-send-email-roman.penyaev@profitbricks.com Cc: Stefan Hajnoczi <stefanha@redhat.com> Cc: Paolo Bonzini <pbonzini@redhat.com> Cc: qemu-devel@nongnu.org Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
* linux-aio: Handle io_submit() failure gracefullyKevin Wolf2016-08-111-1/+7
| | | | | | | | | | | It is generally not expected that io_submit() fails other than with -EAGAIN, but corner cases like SELinux refusing I/O when permissions are revoked are still possible. In this case, we shouldn't abort, but just return an I/O error for the request. Signed-off-by: Kevin Wolf <kwolf@redhat.com> Message-id: 1470741619-23231-1-git-send-email-kwolf@redhat.com Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
* linux-aio: prevent submitting more than MAX_EVENTSRoman Pen2016-07-181-10/+16
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Invoking io_setup(MAX_EVENTS) we ask kernel to create ring buffer for us with specified number of events. But kernel ring buffer allocation logic is a bit tricky (ring buffer is page size aligned + some percpu allocation are required) so eventually more than requested events number is allocated. From a userspace side we have to follow the convention and should not try to io_submit() more or logic, which consumes completed events, should be changed accordingly. The pitfall is in the following sequence: MAX_EVENTS = 128 io_setup(MAX_EVENTS) io_submit(MAX_EVENTS) io_submit(MAX_EVENTS) /* now 256 events are in-flight */ io_getevents(MAX_EVENTS) = 128 /* we can handle only 128 events at once, to be sure * that nothing is pended the io_getevents(MAX_EVENTS) * call must be invoked once more or hang will happen. */ To prevent the hang or reiteration of io_getevents() call this patch restricts the number of in-flights, which is now limited to MAX_EVENTS. Signed-off-by: Roman Pen <roman.penyaev@profitbricks.com> Reviewed-by: Fam Zheng <famz@redhat.com> Reviewed-by: Paolo Bonzini <pbonzini@redhat.com> Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com> Message-id: 1468415004-31755-1-git-send-email-roman.penyaev@profitbricks.com Cc: Stefan Hajnoczi <stefanha@redhat.com> Cc: qemu-devel@nongnu.org Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
* linux-aio: share one LinuxAioState within an AioContextPaolo Bonzini2016-07-181-4/+6
| | | | | | | | | | | | | | | | | | This has better performance because it executes fewer system calls and does not use a bottom half per disk. Originally proposed by Ming Lei. [Changed #include "raw-aio.h" to "block/raw-aio.h" in win32-aio.c to fix build error as reported by Peter Maydell <peter.maydell@linaro.org>. --Stefan] Acked-by: Stefan Hajnoczi <stefanha@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Message-id: 1467650000-51385-1-git-send-email-pbonzini@redhat.com Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com> squash! linux-aio: share one LinuxAioState within an AioContext
* coroutine: move entry argument to qemu_coroutine_createPaolo Bonzini2016-07-131-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | In practice the entry argument is always known at creation time, and it is confusing that sometimes qemu_coroutine_enter is used with a non-NULL argument to re-enter a coroutine (this happens in block/sheepdog.c and tests/test-coroutine.c). So pass the opaque value at creation time, for consistency with e.g. aio_bh_new. Mostly done with the following semantic patch: @ entry1 @ expression entry, arg, co; @@ - co = qemu_coroutine_create(entry); + co = qemu_coroutine_create(entry, arg); ... - qemu_coroutine_enter(co, arg); + qemu_coroutine_enter(co); @ entry2 @ expression entry, arg; identifier co; @@ - Coroutine *co = qemu_coroutine_create(entry); + Coroutine *co = qemu_coroutine_create(entry, arg); ... - qemu_coroutine_enter(co, arg); + qemu_coroutine_enter(co); @ entry3 @ expression entry, arg; @@ - qemu_coroutine_enter(qemu_coroutine_create(entry), arg); + qemu_coroutine_enter(qemu_coroutine_create(entry, arg)); @ reentry @ expression co; @@ - qemu_coroutine_enter(co, NULL); + qemu_coroutine_enter(co); except for the aforementioned few places where the semantic patch stumbled (as expected) and for test_co_queue, which would otherwise produce an uninitialized variable warning. Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Reviewed-by: Fam Zheng <famz@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
* block: fix return code for partial write for Linux AIODenis V. Lunev2016-07-051-1/+1
| | | | | | | | | | | | | | | | Partial write most likely means that there is not space rather than "something wrong happens". Thus it would be more natural to return ENOSPC rather than EINVAL. The problem actually happens with NBD server, which has reported EINVAL rather then ENOSPC on the first error using its protocol, which makes report to the user wrong. Signed-off-by: Denis V. Lunev <den@openvz.org> CC: Pavel Borzenkov <pborzenkov@virtuozzo.com> CC: Kevin Wolf <kwolf@redhat.com> CC: Max Reitz <mreitz@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
* linux-aio: Cancel BH if not neededKevin Wolf2016-06-161-1/+3
| | | | | | | | | | | | | | | | linux-aio uses a BH in order to make sure that the remaining completions are processed even in nested event loops of completion callbacks in order to avoid deadlocks. There is no need, however, to have the BH overhead for the first call into qemu_laio_completion_bh() or after all pending completions have already been processed. Therefore, this patch calls directly into qemu_laio_completion_bh() in qemu_laio_completion_cb() and cancels the BH after qemu_laio_completion_bh() has processed all pending completions. Signed-off-by: Kevin Wolf <kwolf@redhat.com> Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
* raw-posix: Implement .bdrv_co_preadv/pwritevKevin Wolf2016-06-161-5/+2Star
| | | | | | | | | | | | | The raw-posix block driver actually supports byte-aligned requests now on non-O_DIRECT images, like it already (and previously incorrectly) claimed in bs->request_alignment. For some block drivers this means that a RMW cycle can be avoided when they write sub-sector metadata e.g. for cluster allocation. Signed-off-by: Kevin Wolf <kwolf@redhat.com> Reviewed-by: Eric Blake <eblake@redhat.com> Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
* raw-posix: Switch to bdrv_co_* interfacesKevin Wolf2016-06-161-22/+65
| | | | | | | | | | | | | | | | | | In order to use the modern byte-based .bdrv_co_preadv/pwritev() interface, this patch switches raw-posix to coroutine-based interfaces as a first step. In terms of semantics and performance, it doesn't make a difference with the existing code whether we go from a coroutine to a callback-based interface already in block/io.c or only in linux-aio.c As there have been concerns in the past that this change may be a step in the wrong direction with respect to a possible AIO fast path, the old callback-based interface for linux-aio is left around and can be reactivated when a fast path (e.g. directly from virtio-blk dataplane, bypassing the whole block layer) is implemented. Signed-off-by: Kevin Wolf <kwolf@redhat.com> Reviewed-by: Eric Blake <eblake@redhat.com> Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
* linux-aio: make it more type safePaolo Bonzini2016-05-121-29/+17Star
| | | | | | | | Replace void* with an opaque LinuxAioState type. Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Acked-by: Stefan Hajnoczi <stefanha@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
* block: plug whole tree at once, introduce bdrv_io_unplugged_begin/endPaolo Bonzini2016-05-121-8/+5Star
| | | | | | | | | | | | | | Extract the handling of io_plug "depth" from linux-aio.c and let the main bdrv_drain loop do nothing but wait on I/O. Like the two newly introduced functions, bdrv_io_plug and bdrv_io_unplug now operate on all children. The visit order is now symmetrical between plug and unplug, making it possible for formats to implement plug/unplug. Reviewed-by: Fam Zheng <famz@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Acked-by: Stefan Hajnoczi <stefanha@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
* block: Clean up includesPeter Maydell2016-01-201-0/+1
| | | | | | | | | | | Clean up includes so that osdep.h is included first and headers which it implies are not included manually. This commit was created with scripts/clean-includes. Signed-off-by: Peter Maydell <peter.maydell@linaro.org> Reviewed-by: Eric Blake <eblake@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
* aio: Add "is_external" flag for event handlersFam Zheng2015-10-231-2/+3
| | | | | | | | | | All callers pass in false, and the real external ones will switch to true in coming patches. Signed-off-by: Fam Zheng <famz@redhat.com> Reviewed-by: Jeff Cody <jcody@redhat.com> Reviewed-by: Kevin Wolf <kwolf@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
* linux-aio: simplify removal of completed iocbs from the listPaolo Bonzini2014-12-121-6/+6
| | | | | | | | | | | There is no need to do another O(n) pass on the list; the iocb to split the list at is already available through the array we passed to io_submit. Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Reviewed-by: Kevin Wolf <kwolf@redhat.com> Message-id: 1418305950-30924-6-git-send-email-pbonzini@redhat.com Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
* linux-aio: drop return code from laio_io_unplug and ioq_submitPaolo Bonzini2014-12-121-10/+5Star
| | | | | | | | | | These are unused. Suggested-by: Kevin Wolf <kwolf@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Reviewed-by: Kevin Wolf <kwolf@redhat.com> Message-id: 1418305950-30924-5-git-send-email-pbonzini@redhat.com Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
* linux-aio: rename LaioQueue idx field to "n"Paolo Bonzini2014-12-121-6/+6
| | | | | | | | | It does not identify an index in an array anymore. Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Reviewed-by: Kevin Wolf <kwolf@redhat.com> Message-id: 1418305950-30924-4-git-send-email-pbonzini@redhat.com Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
* linux-aio: track whether the queue is blockedPaolo Bonzini2014-12-121-20/+27
| | | | | | | | | | | | | | | | | Avoid that unplug submits requests when io_submit reported that it couldn't accept more; at the same time, try more io_submit calls if it could handle the whole set of requests that were passed, so that the "blocked" flag is reset as soon as possible. After the previous patch, laio_submit already tried to avoid submitting requests to a blocked queue, by comparing s->io_q.idx with "==" instead of the more natural ">=". Switch to the simpler expression now that we have the "blocked" flag. Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Reviewed-by: Kevin Wolf <kwolf@redhat.com> Message-id: 1418305950-30924-3-git-send-email-pbonzini@redhat.com Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
* linux-aio: queue requests that cannot be submittedPaolo Bonzini2014-12-121-42/+33Star
| | | | | | | | | | | | | | Keep a queue of requests that were not submitted; pass them to the kernel when a completion is reported, unless the queue is plugged. The array of iocbs is rebuilt every time from scratch. This avoids keeping the iocbs array and list synchronized. Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Reviewed-by: Kevin Wolf <kwolf@redhat.com> Message-id: 1418305950-30924-2-git-send-email-pbonzini@redhat.com Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
* block: Rename BlockDriverCompletionFunc to BlockCompletionFuncMarkus Armbruster2014-10-201-1/+1
| | | | | | | | | | I'll use it with block backends shortly, and the name is going to fit badly there. It's a block layer thing anyway, not just a block driver thing. Signed-off-by: Markus Armbruster <armbru@redhat.com> Reviewed-by: Max Reitz <mreitz@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
* block: Rename BlockDriverAIOCB* to BlockAIOCB*Markus Armbruster2014-10-201-3/+3
| | | | | | | | | | I'll use BlockDriverAIOCB with block backends shortly, and the name is going to fit badly there. It's a block layer thing anyway, not just a block driver thing. Signed-off-by: Markus Armbruster <armbru@redhat.com> Reviewed-by: Max Reitz <mreitz@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
* block: Rename qemu_aio_release -> qemu_aio_unrefFam Zheng2014-09-221-2/+2
| | | | | | Suggested-by: Benoît Canet <benoit.canet@irqsave.net> Signed-off-by: Fam Zheng <famz@redhat.com> Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
* linux-aio: Convert laio_aiocb_info.cancel to .cancel_asyncFam Zheng2014-09-221-22/+8Star
| | | | | | | | | | | | Just call io_cancel (2), if it fails, it means the request is not canceled, so the event loop will eventually call qemu_laio_process_completion. In qemu_laio_process_completion, change to call the cb unconditionally. It is required by bdrv_aio_cancel_async. Signed-off-by: Fam Zheng <famz@redhat.com> Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
* linux-aio: avoid deadlock in nested aio_poll() callsStefan Hajnoczi2014-08-291-16/+55
| | | | | | | | | | | | | | | | | | | If two Linux AIO request completions are fetched in the same io_getevents() call, QEMU will deadlock if request A's callback waits for request B to complete using an aio_poll() loop. This was reported to happen with the mirror blockjob. This patch moves completion processing into a BH and makes it resumable. Nested event loops can resume completion processing so that request B will complete and the deadlock will not occur. Cc: Kevin Wolf <kwolf@redhat.com> Cc: Paolo Bonzini <pbonzini@redhat.com> Cc: Ming Lei <ming.lei@canonical.com> Cc: Marcin Gibuła <m.gibula@beyond.pl> Reported-by: Marcin Gibuła <m.gibula@beyond.pl> Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com> Tested-by: Marcin Gibuła <m.gibula@beyond.pl>
* linux-aio: Fix laio resource leakGonglei2014-07-151-0/+5
| | | | | | | | | | | | | | | | | when hotplug virtio-scsi disks using laio, the aio_nr will increase in laio_init() by io_setup(), we can see the number by # cat /proc/sys/fs/aio-nr 128 if the aio_nr attach the maxnum, which found from # cat /proc/sys/fs/aio-max-nr 65536 the hotplug process will fail because of aio context leak. Fix it by io_destroy in laio_cleanup(). Reported-by: daifulai <daifulai@huawei.com> Signed-off-by: Gonglei <arei.gonglei@huawei.com> Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
* linux-aio: implement io plug, unplug and flush io queueMing Lei2014-07-071-2/+94
| | | | | | | | | | | | | This patch implements .bdrv_io_plug, .bdrv_io_unplug and .bdrv_flush_io_queue callbacks for linux-aio Block Drivers, so that submitting I/O as a batch can be supported on linux-aio. [Unprocessed requests are completed with -EIO instead of a bogus ret value. --Stefan] Signed-off-by: Ming Lei <ming.lei@canonical.com> Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
* block/linux-aio: fix memory and fd leakStefan Hajnoczi2014-06-041-0/+8
| | | | | | | | | | | Hot unplugging -drive aio=native,file=test.img,format=raw images leaves the Linux AIO event notifier and struct qemu_laio_state allocated. Luckily nothing will use the event notifier after the BlockDriverState has been closed so the handler function is never called. It's still worth fixing this resource leak. Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
* block/raw-posix: implement .bdrv_detach/attach_aio_context()Stefan Hajnoczi2014-06-041-2/+14
| | | | | | | | | | | Drop the assumption that we're using the main AioContext for Linux AIO. Convert the Linux AIO event notifier to use aio_set_event_notifier(). The .bdrv_detach/attach_aio_context() interfaces also need to be implemented to move the event notifier handler from the old to the new AioContext. Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
* aio: drop io_flush argumentStefan Hajnoczi2013-08-191-2/+1Star
| | | | | | | | | | | The .io_flush() handler no longer exists and has no users. Drop the io_flush argument to aio_set_fd_handler() and related functions. The AioFlushEventNotifierHandler and AioFlushHandler typedefs are no longer used and are dropped too. Reviewed-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
* block/linux-aio: drop qemu_laio_completion_cb()Stefan Hajnoczi2013-08-191-15/+2Star
| | | | | | | .io_flush() is no longer called so drop qemu_laio_completion_cb(). It turns out that count is now unused so drop that too. Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
* misc: move include files to include/qemu/Paolo Bonzini2012-12-191-2/+2
| | | | Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
* block: move include files to include/block/Paolo Bonzini2012-12-191-1/+1
| | | | Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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