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perf/core: Flush PMU internal buffers for per-CPU events

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[ Upstream commit a5398bffc01fe044848c5024e5e867e407f239b8 ]

Sometimes the PMU internal buffers have to be flushed for per-CPU events
during a context switch, e.g., large PEBS. Otherwise, the perf tool may
report samples in locations that do not belong to the process where the
samples are processed in, because PEBS does not tag samples with PID/TID.

The current code only flush the buffers for a per-task event. It doesn't
check a per-CPU event.

Add a new event state flag, PERF_ATTACH_SCHED_CB, to indicate that the
PMU internal buffers have to be flushed for this event during a context
switch.

Add sched_cb_entry and perf_sched_cb_usages back to track the PMU/cpuctx
which is required to be flushed.

Only need to invoke the sched_task() for per-CPU events in this patch.
The per-task events have been handled in perf_event_context_sched_in/out
already.

Fixes: 9c964efa43 ("perf/x86/intel: Drain the PEBS buffer during context switches")
Reported-by: Gabriel Marin <gmx@google.com>
Originally-by: Namhyung Kim <namhyung@kernel.org>
Signed-off-by: Kan Liang <kan.liang@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lkml.kernel.org/r/20201130193842.10569-1-kan.liang@linux.intel.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Kan Liang
2020-11-30 11:38:40 -08:00
committed by Greg Kroah-Hartman
parent 3ebd4bd2eb
commit 82ad50c112
2 changed files with 40 additions and 4 deletions
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2
include/linux/perf_event.h
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@@ -606,6 +606,7 @@ struct swevent_hlist {
#define PERF_ATTACH_TASK 0x04
#define PERF_ATTACH_TASK_DATA 0x08
#define PERF_ATTACH_ITRACE 0x10
#define PERF_ATTACH_SCHED_CB 0x20
struct perf_cgroup;
struct perf_buffer;
@@ -872,6 +873,7 @@ struct perf_cpu_context {
struct list_head cgrp_cpuctx_entry;
#endif
struct list_head sched_cb_entry;
int sched_cb_usage;
int online;