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| author | Mikulas Patocka | 2018-08-08 23:22:16 +0200 |
|---|---|---|
| committer | Ingo Molnar | 2018-09-10 15:17:12 +0200 |
| commit | 02101c45ec5b19d607af7372680f5259050b4e9c (patch) | |
| tree | d2b817c7d7490aa655d9a3c4a8193c5c47fd60ad /arch/x86/lib | |
| parent | Linux 4.19-rc3 (diff) | |
| download | kernel-qcow2-linux-02101c45ec5b19d607af7372680f5259050b4e9c.tar.gz kernel-qcow2-linux-02101c45ec5b19d607af7372680f5259050b4e9c.tar.xz kernel-qcow2-linux-02101c45ec5b19d607af7372680f5259050b4e9c.zip | |
x86/asm: Optimize memcpy_flushcache()
I use memcpy_flushcache() in my persistent memory driver for metadata
updates, there are many 8-byte and 16-byte updates and it turns out that
the overhead of memcpy_flushcache causes 2% performance degradation
compared to "movnti" instruction explicitly coded using inline assembler.
The tests were done on a Skylake processor with persistent memory emulated
using the "memmap" kernel parameter. dd was used to copy data to the
dm-writecache target.
This patch recognizes memcpy_flushcache calls with constant short length
and turns them into inline assembler - so that I don't have to use inline
assembler in the driver.
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Snitzer <snitzer@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: device-mapper development <dm-devel@redhat.com>
Link: http://lkml.kernel.org/r/alpine.LRH.2.02.1808081720460.24747@file01.intranet.prod.int.rdu2.redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'arch/x86/lib')
| -rw-r--r-- | arch/x86/lib/usercopy_64.c | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/arch/x86/lib/usercopy_64.c b/arch/x86/lib/usercopy_64.c index 9c5606d88f61..c50a1d815a37 100644 --- a/arch/x86/lib/usercopy_64.c +++ b/arch/x86/lib/usercopy_64.c @@ -153,7 +153,7 @@ long __copy_user_flushcache(void *dst, const void __user *src, unsigned size) return rc; } -void memcpy_flushcache(void *_dst, const void *_src, size_t size) +void __memcpy_flushcache(void *_dst, const void *_src, size_t size) { unsigned long dest = (unsigned long) _dst; unsigned long source = (unsigned long) _src; @@ -216,7 +216,7 @@ void memcpy_flushcache(void *_dst, const void *_src, size_t size) clean_cache_range((void *) dest, size); } } -EXPORT_SYMBOL_GPL(memcpy_flushcache); +EXPORT_SYMBOL_GPL(__memcpy_flushcache); void memcpy_page_flushcache(char *to, struct page *page, size_t offset, size_t len) |