diff options
| author | Peter Zijlstra <peterz@infradead.org> | 2023-10-10 00:04:25 +0300 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2023-11-20 13:58:53 +0300 |
| commit | b0ebeb5956e5eae19c1520fb78197a252aabc4c3 (patch) | |
| tree | a3eb420efc07d0552d75779ececb976f14ca7be9 /include/linux | |
| parent | ad5cb6deb41417ef41b9d6ff54f789212108606f (diff) | |
| download | linux-b0ebeb5956e5eae19c1520fb78197a252aabc4c3.tar.xz | |
perf: Optimize perf_cgroup_switch()
[ Upstream commit f06cc667f79909e9175460b167c277b7c64d3df0 ]
Namhyung reported that bd2756811766 ("perf: Rewrite core context handling")
regresses context switch overhead when perf-cgroup is in use together
with 'slow' PMUs like uncore.
Specifically, perf_cgroup_switch()'s perf_ctx_disable() /
ctx_sched_out() etc.. all iterate the full list of active PMUs for
that CPU, even if they don't have cgroup events.
Previously there was cgrp_cpuctx_list which linked the relevant PMUs
together, but that got lost in the rework. Instead of re-instruducing
a similar list, let the perf_event_pmu_context iteration skip those
that do not have cgroup events. This avoids growing multiple versions
of the perf_event_pmu_context iteration.
Measured performance (on a slightly different patch):
Before)
$ taskset -c 0 ./perf bench sched pipe -l 10000 -G AAA,BBB
# Running 'sched/pipe' benchmark:
# Executed 10000 pipe operations between two processes
Total time: 0.901 [sec]
90.128700 usecs/op
11095 ops/sec
After)
$ taskset -c 0 ./perf bench sched pipe -l 10000 -G AAA,BBB
# Running 'sched/pipe' benchmark:
# Executed 10000 pipe operations between two processes
Total time: 0.065 [sec]
6.560100 usecs/op
152436 ops/sec
Fixes: bd2756811766 ("perf: Rewrite core context handling")
Reported-by: Namhyung Kim <namhyung@kernel.org>
Debugged-by: Namhyung Kim <namhyung@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20231009210425.GC6307@noisy.programming.kicks-ass.net
Signed-off-by: Sasha Levin <sashal@kernel.org>
Diffstat (limited to 'include/linux')
| -rw-r--r-- | include/linux/perf_event.h | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h index 7b5406e3288d..16913318af93 100644 --- a/include/linux/perf_event.h +++ b/include/linux/perf_event.h @@ -879,6 +879,7 @@ struct perf_event_pmu_context { unsigned int embedded : 1; unsigned int nr_events; + unsigned int nr_cgroups; atomic_t refcount; /* event <-> epc */ struct rcu_head rcu_head; |