Commit 11f52002 authored by Arnd Bergmann's avatar Arnd Bergmann

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
parents a746568e 57006d3e
......@@ -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.
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