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linux/Documentation/admin-guide/perf/arm-ccn.rst

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docs: perf: convert to ReST Rename the perf documentation files to ReST, add an index for them and adjust in order to produce a nice html output via the Sphinx build system. At its new index.rst, let's add a :orphan: while this is not linked to the main index.rst file, in order to avoid build warnings. Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
2019-04-19 04:35:40 +08:00
==========================
bus: ARM CCN PMU driver Driver providing perf backend for ARM Cache Coherent Network interconnect. Supports counting all hardware events and crosspoint watchpoints. Currently works with CCN-504 only, although there should be no changes required for CCN-508 (just impossible to test it now). Signed-off-by: Pawel Moll <pawel.moll@arm.com> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
2014-07-23 01:32:59 +08:00
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
bus: arm-ccn: Correct required arguments for XP PMU events XP can provide events from two sources: watchpoints, observing traffic on device ports and PMU looking at internal buses. Unfortunately the sysfs definition of the PMU events was requiring port number (instead of bus number) and direction (the buses are unidirectional), as these fields were shared with the watchpoint event. Although it does not introduce a major problem (port can be used as bus alias and direction is simply ignored for XP PMU events), it's better to fix it now, before external tools start depending on this behaviour. Signed-off-by: Pawel Moll <pawel.moll@arm.com>
2016-08-11 18:56:28 +08:00
explicitly specified.
bus: ARM CCN PMU driver Driver providing perf backend for ARM Cache Coherent Network interconnect. Supports counting all hardware events and crosspoint watchpoints. Currently works with CCN-504 only, although there should be no changes required for CCN-508 (just impossible to test it now). Signed-off-by: Pawel Moll <pawel.moll@arm.com> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
2014-07-23 01:32:59 +08:00
bus: arm-ccn: Correct required arguments for XP PMU events XP can provide events from two sources: watchpoints, observing traffic on device ports and PMU looking at internal buses. Unfortunately the sysfs definition of the PMU events was requiring port number (instead of bus number) and direction (the buses are unidirectional), as these fields were shared with the watchpoint event. Although it does not introduce a major problem (port can be used as bus alias and direction is simply ignored for XP PMU events), it's better to fix it now, before external tools start depending on this behaviour. Signed-off-by: Pawel Moll <pawel.moll@arm.com>
2016-08-11 18:56:28 +08:00
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.
docs: perf: convert to ReST Rename the perf documentation files to ReST, add an index for them and adjust in order to produce a nice html output via the Sphinx build system. At its new index.rst, let's add a :orphan: while this is not linked to the main index.rst file, in order to avoid build warnings. Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
2019-04-19 04:35:40 +08:00
bus: ARM CCN PMU driver Driver providing perf backend for ARM Cache Coherent Network interconnect. Supports counting all hardware events and crosspoint watchpoints. Currently works with CCN-504 only, although there should be no changes required for CCN-508 (just impossible to test it now). Signed-off-by: Pawel Moll <pawel.moll@arm.com> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
2014-07-23 01:32:59 +08:00
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.
bus: arm-ccn: cpumask attribute This patch adds a "cpumask" attribute to CCN's event_source class sysfs directory. Perf user tool uses it to restrict events to the processor(s) enumerated in this mask. This patch provides a single CPU mask, making it possible to run "-a" perf session (previously it would request the same CCN event, for example cycle counter, on each available core and most likely fail). Initially the mask is set to the CPU that happened to probe the driver, but it will be changed when it is hot-un-plugged (active events are migrated to another CPU then). Example: Performance counter stats for 'system wide': CPU0 2968148 cycles CPU1 2236736 cycles CPU2 1797968 cycles CPU3 1831715 cycles CPU1 1201850868 ccn/cycles/ 1.001241383 seconds time elapsed Signed-off-by: Pawel Moll <pawel.moll@arm.com>
2015-04-16 19:14:35 +08:00
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.
docs: perf: convert to ReST Rename the perf documentation files to ReST, add an index for them and adjust in order to produce a nice html output via the Sphinx build system. At its new index.rst, let's add a :orphan: while this is not linked to the main index.rst file, in order to avoid build warnings. Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
2019-04-19 04:35:40 +08:00
Example of perf tool use::
bus: ARM CCN PMU driver Driver providing perf backend for ARM Cache Coherent Network interconnect. Supports counting all hardware events and crosspoint watchpoints. Currently works with CCN-504 only, although there should be no changes required for CCN-508 (just impossible to test it now). Signed-off-by: Pawel Moll <pawel.moll@arm.com> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
2014-07-23 01:32:59 +08:00
docs: perf: convert to ReST Rename the perf documentation files to ReST, add an index for them and adjust in order to produce a nice html output via the Sphinx build system. At its new index.rst, let's add a :orphan: while this is not linked to the main index.rst file, in order to avoid build warnings. Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
2019-04-19 04:35:40 +08:00
/ # perf list | grep ccn
ccn/cycles/ [Kernel PMU event]
<...>
ccn/xp_valid_flit,xp=?,port=?,vc=?,dir=?/ [Kernel PMU event]
<...>
bus: ARM CCN PMU driver Driver providing perf backend for ARM Cache Coherent Network interconnect. Supports counting all hardware events and crosspoint watchpoints. Currently works with CCN-504 only, although there should be no changes required for CCN-508 (just impossible to test it now). Signed-off-by: Pawel Moll <pawel.moll@arm.com> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
2014-07-23 01:32:59 +08:00
docs: perf: convert to ReST Rename the perf documentation files to ReST, add an index for them and adjust in order to produce a nice html output via the Sphinx build system. At its new index.rst, let's add a :orphan: while this is not linked to the main index.rst file, in order to avoid build warnings. Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
2019-04-19 04:35:40 +08:00
/ # perf stat -a -e ccn/cycles/,ccn/xp_valid_flit,xp=1,port=0,vc=1,dir=1/ \
sleep 1
bus: ARM CCN PMU driver Driver providing perf backend for ARM Cache Coherent Network interconnect. Supports counting all hardware events and crosspoint watchpoints. Currently works with CCN-504 only, although there should be no changes required for CCN-508 (just impossible to test it now). Signed-off-by: Pawel Moll <pawel.moll@arm.com> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
2014-07-23 01:32:59 +08:00
The driver does not support sampling, therefore "perf record" will
bus: arm-ccn: cpumask attribute This patch adds a "cpumask" attribute to CCN's event_source class sysfs directory. Perf user tool uses it to restrict events to the processor(s) enumerated in this mask. This patch provides a single CPU mask, making it possible to run "-a" perf session (previously it would request the same CCN event, for example cycle counter, on each available core and most likely fail). Initially the mask is set to the CPU that happened to probe the driver, but it will be changed when it is hot-un-plugged (active events are migrated to another CPU then). Example: Performance counter stats for 'system wide': CPU0 2968148 cycles CPU1 2236736 cycles CPU2 1797968 cycles CPU3 1831715 cycles CPU1 1201850868 ccn/cycles/ 1.001241383 seconds time elapsed Signed-off-by: Pawel Moll <pawel.moll@arm.com>
2015-04-16 19:14:35 +08:00
not work. Per-task (without "-a") perf sessions are not supported.