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authorDavid Carrillo-Cisneros <davidcc@google.com>2016-11-01 11:52:58 -0700
committerIngo Molnar <mingo@kernel.org>2016-11-15 14:18:22 +0100
commit864c2357ca898c6171fe5284f5ecc795c8ce27a8 (patch)
treee0c20d547643510866dc617d83fb1e5eab7f67bd /kernel/acct.c
parente76d21c40bd6c67fd4e2c1540d77e113df962b4d (diff)
perf/core: Do not set cpuctx->cgrp for unscheduled cgroups
Commit: db4a835601b7 ("perf/core: Set cgroup in CPU contexts for new cgroup events") failed to verify that event->cgrp is actually the scheduled cgroup in a CPU before setting cpuctx->cgrp. This patch fixes that. Now that there is a different path for scheduled and unscheduled cgroup, add a warning to catch when cpuctx->cgrp is still set after the last cgroup event has been unsheduled. To verify the bug: # Create 2 cgroups. mkdir /dev/cgroups/devices/g1 mkdir /dev/cgroups/devices/g2 # launch a task, bind it to a cpu and move it to g1 CPU=2 while :; do : ; done & P=$! taskset -pc $CPU $P echo $P > /dev/cgroups/devices/g1/tasks # monitor g2 (it runs no tasks) and observe output perf stat -e cycles -I 1000 -C $CPU -G g2 # time counts unit events 1.000091408 7,579,527 cycles g2 2.000350111 <not counted> cycles g2 3.000589181 <not counted> cycles g2 4.000771428 <not counted> cycles g2 # note first line that displays that a task run in g2, despite # g2 having no tasks. This is because cpuctx->cgrp was wrongly # set when context of new event was installed. # After applying the fix we obtain the right output: perf stat -e cycles -I 1000 -C $CPU -G g2 # time counts unit events 1.000119615 <not counted> cycles g2 2.000389430 <not counted> cycles g2 3.000590962 <not counted> cycles g2 Signed-off-by: David Carrillo-Cisneros <davidcc@google.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com> Cc: Arnaldo Carvalho de Melo <acme@redhat.com> Cc: Jiri Olsa <jolsa@redhat.com> Cc: Kan Liang <kan.liang@intel.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Nilay Vaish <nilayvaish@gmail.com> Cc: Paul Turner <pjt@google.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Stephane Eranian <eranian@google.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Vegard Nossum <vegard.nossum@gmail.com> Link: http://lkml.kernel.org/r/1478026378-86083-1-git-send-email-davidcc@google.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'kernel/acct.c')
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