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perf/x86-ibs: Fix frequency profiling 

Fixing profiling at a fixed frequency, in this case the freq value and
sample period was setup incorrectly. Since sampling periods are
adjusted we also allow periods that have lower 4 bits set.

Another fix is the setup of the hw counter: If we modify
hwc->sample_period, we also need to update hwc->last_period and
hwc->period_left.

Signed-off-by: Robert Richter <robert.richter@amd.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1333390758-10893-5-git-send-email-robert.richter@amd.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Robert Richter 2012-04-02 20:19:10 +02:00 committed by Ingo Molnar
parent 7bf352384f
commit 6accb9cf76
1 changed files with 16 additions and 2 deletions
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18
arch/x86/kernel/cpu/perf_event_amd_ibs.c
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@ -162,9 +162,16 @@ static int perf_ibs_init(struct perf_event *event)
if (config & perf_ibs->cnt_mask)
/* raw max_cnt may not be set */
return -EINVAL;
if (hwc->sample_period & 0x0f)
/* lower 4 bits can not be set in ibs max cnt */
if (!event->attr.sample_freq && hwc->sample_period & 0x0f)
/*
* lower 4 bits can not be set in ibs max cnt,
* but allowing it in case we adjust the
* sample period to set a frequency.
*/
return -EINVAL;
hwc->sample_period &= ~0x0FULL;
if (!hwc->sample_period)
hwc->sample_period = 0x10;
} else {
max_cnt = config & perf_ibs->cnt_mask;
config &= ~perf_ibs->cnt_mask;
@ -175,6 +182,13 @@ static int perf_ibs_init(struct perf_event *event)
if (!hwc->sample_period)
return -EINVAL;
/*
* If we modify hwc->sample_period, we also need to update
* hwc->last_period and hwc->period_left.
*/
hwc->last_period = hwc->sample_period;
local64_set(&hwc->period_left, hwc->sample_period);
hwc->config_base = perf_ibs->msr;
hwc->config = config;