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| author | Stephane Eranian <eranian@google.com> | 2010-02-01 14:50:01 +0200 |
|---|---|---|
| committer | Ingo Molnar <mingo@elte.hu> | 2010-02-04 09:59:50 +0100 |
| commit | 447a194b393f32699607fd99617a40abd6a95114 (patch) | |
| tree | 7d202a6ad8f80c913a4e3d439eedf5ba0abbbf39 /include/linux/perf_event.h | |
| parent | fce877e3a429940a986e085a41e8b57f2d922e36 (diff) | |
| download | lwn-447a194b393f32699607fd99617a40abd6a95114.tar.gz lwn-447a194b393f32699607fd99617a40abd6a95114.zip | |
perf_events, x86: Fix bug in hw_perf_enable()
We cannot assume that because hwc->idx == assign[i], we can avoid
reprogramming the counter in hw_perf_enable().
The event may have been scheduled out and another event may have been
programmed into this counter. Thus, we need a more robust way of
verifying if the counter still contains config/data related to an event.
This patch adds a generation number to each counter on each cpu. Using
this mechanism we can verify reliabilty whether the content of a counter
corresponds to an event.
Signed-off-by: Stephane Eranian <eranian@google.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
LKML-Reference: <4b66dc67.0b38560a.1635.ffffae18@mx.google.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'include/linux/perf_event.h')
| -rw-r--r-- | include/linux/perf_event.h | 2 |
1 files changed, 2 insertions, 0 deletions
diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h index 556b0f4a668e..071a7db52549 100644 --- a/include/linux/perf_event.h +++ b/include/linux/perf_event.h @@ -478,9 +478,11 @@ struct hw_perf_event { union { struct { /* hardware */ u64 config; + u64 last_tag; unsigned long config_base; unsigned long event_base; int idx; + int last_cpu; }; struct { /* software */ s64 remaining; |