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Date: Tue, 30 Aug 2016 08:47:24 +0200 From: Peter Zijlstra <peterz@...radead.org> To: Jiri Olsa <jolsa@...hat.com> Cc: Vegard Nossum <vegard.nossum@...il.com>, Thomas Gleixner <tglx@...utronix.de>, Stephane Eranian <eranian@...gle.com>, Vince Weaver <vincent.weaver@...ne.edu>, Ingo Molnar <mingo@...nel.org>, David Carrillo-Cisneros <davidcc@...gle.com>, "H. Peter Anvin" <hpa@...or.com>, Kan Liang <kan.liang@...el.com>, Arnaldo Carvalho de Melo <acme@...hat.com>, Paul Turner <pjt@...gle.com>, Linus Torvalds <torvalds@...ux-foundation.org>, LKML <linux-kernel@...r.kernel.org>, Alexander Shishkin <alexander.shishkin@...ux.intel.com>, linux-tip-commits@...r.kernel.org Subject: Re: [tip:perf/core] perf/core: Check return value of the perf_event_read() IPI On Mon, Aug 29, 2016 at 08:58:41PM +0200, Jiri Olsa wrote: > couldn't we just call smp_call_function_single(cpu_to_read, __perf_event_read, ... > once we read oncpu != -1 ? > Yes, and at that point we can simply revert this WARN, because that is exactly the same. Which I think is what I'm going to do. If oncpu is not valid, the sched_out that made it invalid will have updated the event count and we're good. All I'll leave is an explicit comment that we've ignored the smp_call_function_single() return value on purpose.
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