From: Peter Zijlstra <peterz@infradead.org>
To: Andi Kleen <ak@linux.intel.com>
Cc: Kyle Huey <me@kylehuey.com>,
Kan Liang <kan.liang@linux.intel.com>,
Ingo Molnar <mingo@kernel.org>,
Robert O'Callahan <robert@ocallahan.org>,
Alexander Shishkin <alexander.shishkin@linux.intel.com>,
Arnaldo Carvalho de Melo <acme@redhat.com>,
Jiri Olsa <jolsa@redhat.com>,
Linus Torvalds <torvalds@linux-foundation.org>,
Stephane Eranian <eranian@google.com>,
Thomas Gleixner <tglx@linutronix.de>,
Vince Weaver <vincent.weaver@maine.edu>,
acme@kernel.org, open list <linux-kernel@vger.kernel.org>
Subject: Re: [REGRESSION] x86, perf: counter freezing breaks rr
Date: Wed, 21 Nov 2018 09:14:20 +0100 [thread overview]
Message-ID: <20181121081420.GF2131@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <20181120223854.GH13936@tassilo.jf.intel.com>
On Tue, Nov 20, 2018 at 02:38:54PM -0800, Andi Kleen wrote:
> > In fact, I'll argue FREEZE_ON_OVERFLOW is unfixably broken for
> > independent counters, because while one counter overflows, we'll stall
> > counting on all others until we've handled the PMI.
> >
> > Even though the PMI might not be for them and they very much want/need
> > to continue counting.
>
> We stop all counters in any case for the PMI. With freeze-on-PMI it just
> happens slightly earlier.
Hiding the PMI is fine and good. The PMI is not the workload. Stopping
it earlier is _NOT_ good, it hides your actual workload.
next prev parent reply other threads:[~2018-11-21 8:14 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-11-20 16:19 [REGRESSION] x86, perf: counter freezing breaks rr Kyle Huey
2018-11-20 17:08 ` Peter Zijlstra
2018-11-20 17:59 ` [tip:perf/urgent] perf/x86/intel: Fix regression by default disabling perfmon v4 interrupt handling tip-bot for Peter Zijlstra
2018-11-20 18:20 ` [REGRESSION] x86, perf: counter freezing breaks rr Stephane Eranian
2018-11-20 19:50 ` Kyle Huey
2018-11-20 19:41 ` Andi Kleen
2018-11-20 19:54 ` Kyle Huey
2018-11-20 20:11 ` Andi Kleen
2018-11-20 20:53 ` Kyle Huey
2018-11-20 21:18 ` Andi Kleen
2018-11-20 21:46 ` Kyle Huey
2018-11-20 22:19 ` Andi Kleen
2018-11-20 21:19 ` Stephane Eranian
2018-11-20 21:34 ` Kyle Huey
2018-11-20 22:16 ` Peter Zijlstra
2018-11-20 22:25 ` Peter Zijlstra
2018-11-20 22:38 ` Andi Kleen
2018-11-21 8:14 ` Peter Zijlstra [this message]
2018-11-27 22:08 ` Kyle Huey
2018-11-27 23:36 ` Andi Kleen
2018-11-28 1:25 ` Stephane Eranian
2018-11-29 14:50 ` Liang, Kan
2018-11-29 15:35 ` Peter Zijlstra
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