Messages in this thread | | | Date | Tue, 24 Jun 2014 12:53:01 +0200 | From | Jiri Olsa <> | Subject | Re: [PATCH 2/3] perf: Do not allow optimized switch for non-cloned events |
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On Tue, Jun 24, 2014 at 12:39:36PM +0200, Peter Zijlstra wrote: > On Tue, Jun 24, 2014 at 10:20:25AM +0200, Jiri Olsa wrote: > > From: Jiri Olsa <jolsa@redhat.com> > > > > The context check in perf_event_context_sched_out allows > > non-cloned context to be part of the optimized schedule > > out switch. > > > > This could move non-cloned context into another workload > > child. Once this child exits, the context is closed and > > leaves all original (parent) events in closed state. > > > > Any other new cloned event will have closed state and not > > measure anything. And probably causing other odd bugs. > > > > Cc: Arnaldo Carvalho de Melo <acme@kernel.org> > > Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com> > > Cc: David Ahern <dsahern@gmail.com> > > Cc: Frederic Weisbecker <fweisbec@gmail.com> > > Cc: Ingo Molnar <mingo@kernel.org> > > Cc: Namhyung Kim <namhyung@kernel.org> > > Cc: Paul Mackerras <paulus@samba.org> > > Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> > > Signed-off-by: Jiri Olsa <jolsa@kernel.org> > > --- > > kernel/events/core.c | 2 +- > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > diff --git a/kernel/events/core.c b/kernel/events/core.c > > index d968008..4e3618e 100644 > > --- a/kernel/events/core.c > > +++ b/kernel/events/core.c > > @@ -2319,7 +2319,7 @@ static void perf_event_context_sched_out(struct task_struct *task, int ctxn, > > next_parent = rcu_dereference(next_ctx->parent_ctx); > > > > /* If neither context have a parent context; they cannot be clones. */ > > - if (!parent && !next_parent) > > + if (!parent || !next_parent) > > goto unlock; > > > > if (next_parent == ctx || next_ctx == parent || next_parent == parent) { > > Ohh, nice, good catch!
should I queue it with your ack?
jirka
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