From: Peter Zijlstra <peterz@infradead.org>
To: Andi Kleen <ak@linux.intel.com>
Cc: "Liang, Kan" <kan.liang@intel.com>,
Stephane Eranian <eranian@google.com>,
"tglx@linutronix.de" <tglx@linutronix.de>,
"mingo@redhat.com" <mingo@redhat.com>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"acme@kernel.org" <acme@kernel.org>
Subject: Re: [PATCH V5 4/8] perf/x86/intel/uncore: add new data structures for free running counters
Date: Fri, 19 Jan 2018 22:33:55 +0100 [thread overview]
Message-ID: <20180119213355.GE2269@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <20180119202417.GK7844@tassilo.jf.intel.com>
On Fri, Jan 19, 2018 at 12:24:17PM -0800, Andi Kleen wrote:
> > Oh, think a bit more.
> > I think we cannot do the same thing as we did for CPU PMU's fixed counters.
> >
> > The counters here are free running counters. They cannot be start/stop.
>
> Yes free running counter have completely different semantics. They
> need a separate event code.
The only thing that matters is if they count the same thing or not.
The not start/stop thing is not important. See arch/x86/events/msr.c on
how to deal with that. The short story is that you simply ignore stop
and update the prev_count on start. Then any next update will increment
with the correct delta.
(if the counter is short you also need to run a timer to deal with
wraps).
next prev parent reply other threads:[~2018-01-19 21:34 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-01-15 18:57 [PATCH V5 1/8] perf/x86/intel/uncore: customized event_read for client IMC uncore kan.liang
2018-01-15 18:57 ` [PATCH V5 2/8] perf/x86/intel/uncore: correct fixed counter index check for NHM kan.liang
2018-01-15 18:57 ` [PATCH V5 3/8] perf/x86/intel/uncore: correct fixed counter index check in generic code kan.liang
2018-01-15 18:57 ` [PATCH V5 4/8] perf/x86/intel/uncore: add new data structures for free running counters kan.liang
2018-01-18 13:32 ` Peter Zijlstra
2018-01-18 17:43 ` Liang, Kan
2018-01-19 13:07 ` Peter Zijlstra
2018-01-19 15:15 ` Liang, Kan
2018-01-19 17:19 ` Peter Zijlstra
2018-01-19 17:34 ` Stephane Eranian
2018-01-19 17:53 ` Liang, Kan
2018-01-19 17:55 ` Stephane Eranian
2018-01-19 18:00 ` Liang, Kan
2018-01-19 20:18 ` Stephane Eranian
2018-01-19 20:24 ` Andi Kleen
2018-01-19 20:50 ` Stephane Eranian
2018-01-19 20:51 ` Stephane Eranian
2018-01-20 1:24 ` Andi Kleen
2018-01-19 21:33 ` Peter Zijlstra [this message]
2018-01-23 22:00 ` Liang, Kan
2018-01-24 10:17 ` Peter Zijlstra
2018-01-24 15:46 ` Liang, Kan
2018-01-15 18:57 ` [PATCH V5 5/8] perf/x86/intel/uncore: add infrastructure for free running counter kan.liang
2018-01-15 18:57 ` [PATCH V5 6/8] perf/x86/intel/uncore: SKX support for IIO free running counters kan.liang
2018-01-15 18:57 ` [PATCH V5 7/8] perf/x86/intel/uncore: expose uncore_pmu_event functions kan.liang
2018-01-15 18:57 ` [PATCH V5 8/8] perf/x86/intel/uncore: clean up client IMC uncore kan.liang
2018-01-18 9:36 ` [PATCH V5 1/8] perf/x86/intel/uncore: customized event_read for " Thomas Gleixner
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