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author | Linus Torvalds | 2019-07-16 21:21:41 +0200 |
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committer | Linus Torvalds | 2019-07-16 21:21:41 +0200 |
commit | c309b6f24222246c18a8b65d3950e6e755440865 (patch) | |
tree | 11893170f5c246bb0dee8066e85878af04162ab0 /Documentation/admin-guide/perf/arm-ccn.rst | |
parent | Merge tag 'xtensa-20190715' of git://github.com/jcmvbkbc/linux-xtensa (diff) | |
parent | docs: kbuild: fix build with pdf and fix some minor issues (diff) | |
download | kernel-qcow2-linux-c309b6f24222246c18a8b65d3950e6e755440865.tar.gz kernel-qcow2-linux-c309b6f24222246c18a8b65d3950e6e755440865.tar.xz kernel-qcow2-linux-c309b6f24222246c18a8b65d3950e6e755440865.zip |
Merge tag 'docs/v5.3-1' of git://git.kernel.org/pub/scm/linux/kernel/git/mchehab/linux-media
Pull rst conversion of docs from Mauro Carvalho Chehab:
"As agreed with Jon, I'm sending this big series directly to you, c/c
him, as this series required a special care, in order to avoid
conflicts with other trees"
* tag 'docs/v5.3-1' of git://git.kernel.org/pub/scm/linux/kernel/git/mchehab/linux-media: (77 commits)
docs: kbuild: fix build with pdf and fix some minor issues
docs: block: fix pdf output
docs: arm: fix a breakage with pdf output
docs: don't use nested tables
docs: gpio: add sysfs interface to the admin-guide
docs: locking: add it to the main index
docs: add some directories to the main documentation index
docs: add SPDX tags to new index files
docs: add a memory-devices subdir to driver-api
docs: phy: place documentation under driver-api
docs: serial: move it to the driver-api
docs: driver-api: add remaining converted dirs to it
docs: driver-api: add xilinx driver API documentation
docs: driver-api: add a series of orphaned documents
docs: admin-guide: add a series of orphaned documents
docs: cgroup-v1: add it to the admin-guide book
docs: aoe: add it to the driver-api book
docs: add some documentation dirs to the driver-api book
docs: driver-model: move it to the driver-api book
docs: lp855x-driver.rst: add it to the driver-api book
...
Diffstat (limited to 'Documentation/admin-guide/perf/arm-ccn.rst')
-rw-r--r-- | Documentation/admin-guide/perf/arm-ccn.rst | 61 |
1 files changed, 61 insertions, 0 deletions
diff --git a/Documentation/admin-guide/perf/arm-ccn.rst b/Documentation/admin-guide/perf/arm-ccn.rst new file mode 100644 index 000000000000..832b0c64023a --- /dev/null +++ b/Documentation/admin-guide/perf/arm-ccn.rst @@ -0,0 +1,61 @@ +========================== +ARM Cache Coherent Network +========================== + +CCN-504 is a ring-bus interconnect consisting of 11 crosspoints +(XPs), with each crosspoint supporting up to two device ports, +so nodes (devices) 0 and 1 are connected to crosspoint 0, +nodes 2 and 3 to crosspoint 1 etc. + +PMU (perf) driver +----------------- + +The CCN driver registers a perf PMU driver, which provides +description of available events and configuration options +in sysfs, see /sys/bus/event_source/devices/ccn*. + +The "format" directory describes format of the config, config1 +and config2 fields of the perf_event_attr structure. The "events" +directory provides configuration templates for all documented +events, that can be used with perf tool. For example "xp_valid_flit" +is an equivalent of "type=0x8,event=0x4". Other parameters must be +explicitly specified. + +For events originating from device, "node" defines its index. + +Crosspoint PMU events require "xp" (index), "bus" (bus number) +and "vc" (virtual channel ID). + +Crosspoint watchpoint-based events (special "event" value 0xfe) +require "xp" and "vc" as as above plus "port" (device port index), +"dir" (transmit/receive direction), comparator values ("cmp_l" +and "cmp_h") and "mask", being index of the comparator mask. + +Masks are defined separately from the event description +(due to limited number of the config values) in the "cmp_mask" +directory, with first 8 configurable by user and additional +4 hardcoded for the most frequent use cases. + +Cycle counter is described by a "type" value 0xff and does +not require any other settings. + +The driver also provides a "cpumask" sysfs attribute, which contains +a single CPU ID, of the processor which will be used to handle all +the CCN PMU events. It is recommended that the user space tools +request the events on this processor (if not, the perf_event->cpu value +will be overwritten anyway). In case of this processor being offlined, +the events are migrated to another one and the attribute is updated. + +Example of perf tool use:: + + / # perf list | grep ccn + ccn/cycles/ [Kernel PMU event] + <...> + ccn/xp_valid_flit,xp=?,port=?,vc=?,dir=?/ [Kernel PMU event] + <...> + + / # perf stat -a -e ccn/cycles/,ccn/xp_valid_flit,xp=1,port=0,vc=1,dir=1/ \ + sleep 1 + +The driver does not support sampling, therefore "perf record" will +not work. Per-task (without "-a") perf sessions are not supported. |