Sukadev,

On 15.10.12 17:55:34, Robert Richter wrote:

On 11.10.12 18:28:39, Sukadev Bhattiprolu wrote:

quoted

+  { .type = PERF_TYPE_HARDWARE, .config = PERF_COUNT_HW_STALLED_CYCLES_FIXED_POINT },
+  { .type = PERF_TYPE_HARDWARE, .config = PERF_COUNT_HW_STALLED_CYCLES_LOAD_STORE },
+  { .type = PERF_TYPE_HARDWARE, .config = PERF_COUNT_HW_STALLED_CYCLES_INSTRUCTION_FETCH },
+  { .type = PERF_TYPE_HARDWARE, .config = PERF_COUNT_HW_STALLED_CYCLES_BRANCH },

Instead of adding new hardware event types I would prefer to use raw
events in conjunction with sysfs, see e.g. the intel-uncore
implementation. Something like:

 $ find /sys/bus/event_source/devices/cpu/events/
 ...
 /sys/bus/event_source/devices/cpu/events/stalled-cycles-fixed-point
 /sys/bus/event_source/devices/cpu/events/stalled-cycles-load-store
 /sys/bus/event_source/devices/cpu/events/stalled-cycles-instruction-fetch
 /sys/bus/event_source/devices/cpu/events/stalled-cycles-branch
 ...
 $ cat /sys/bus/event_source/devices/cpu/events/stalled-cycles-fixed-point
 event=0xff,umask=0x00

Perf tool works then out-of-the-box with:

 $ perf record -e cpu/stalled-cycles-fixed-point/ ...

I refer here to arch/x86/kernel/cpu/perf_event_intel_uncore.c (should
be in v3.7-rc1 or tip:perf/core). See the INTEL_UNCORE_EVENT_DESC()
macro and 'if (type->event_descs) ...' in uncore_type_init(). The code
should be reworked to be non-architectural.

PMU registration is implemented for a longer time already for all
architectures and pmu types:

 /sys/bus/event_source/devices/*

But

 /sys/bus/event_source/devices/*/events/

exists only for a small number of pmus. Perf tool support of this was
implemented with:

 a6146d5 perf/tool: Add PMU event alias support

-Robert

-- 
Advanced Micro Devices, Inc.
Operating System Research Center