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| author | Arnd Bergmann <arnd@arndb.de> | 2015-05-12 16:47:51 +0200 |
|---|---|---|
| committer | Arnd Bergmann <arnd@arndb.de> | 2015-05-12 16:47:51 +0200 |
| commit | 11f52002bfb4ceef26f04ab46cabd37e90f6b1ed (patch) | |
| tree | b92358373fb12166fc59f3d9b9251f1434fb0f9f /Documentation | |
| parent | a746568e5173214f0fa1b532c6c2f12482bc637f (diff) | |
| parent | 57006d3e6f62def53c01ae3ffc338caebd866e89 (diff) | |
Merge tag 'ccn/updates-for-4.2' of git://git.linaro.org/people/pawel.moll/linux into next/drivers
Pull "Set of ARM CCN PMU driver updates" from Pawel Moll:
- fixed a nasty bitfield mangling bug
- added new hints to the perf userspace tool
- pinned events processing to a single PMU
- modified events initialisation so they can be rotated now
* tag 'ccn/updates-for-4.2' of git://git.linaro.org/people/pawel.moll/linux:
bus: arm-ccn: Allocate event when it is being added, not initialised
bus: arm-ccn: Do not group CCN events with other PMUs
bus: arm-ccn: Provide required event arguments
bus: arm-ccn: cpumask attribute
bus: arm-ccn: Fix node->XP config conversion
Diffstat (limited to 'Documentation')
| -rw-r--r-- | Documentation/arm/CCN.txt | 17 |
1 files changed, 10 insertions, 7 deletions
diff --git a/Documentation/arm/CCN.txt b/Documentation/arm/CCN.txt index 0632b3aad83e..ffca443a19b4 100644 --- a/Documentation/arm/CCN.txt +++ b/Documentation/arm/CCN.txt @@ -33,20 +33,23 @@ directory, with first 8 configurable by user and additional 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/ [Kernel PMU event] + ccn/xp_valid_flit,xp=?,port=?,vc=?,dir=?/ [Kernel PMU event] <...> -/ # perf stat -C 0 -e ccn/cycles/,ccn/xp_valid_flit,xp=1,port=0,vc=1,dir=1/ \ +/ # 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. Also notice that only single cpu is being selected -("-C 0") - this is because perf framework does not support -"non-CPU related" counters (yet?) so system-wide session ("-a") -would try (and in most cases fail) to set up the same event -per each CPU. +not work. Per-task (without "-a") perf sessions are not supported. |