From: Mark Rutland <mark.rutland@arm.com>
To: Kan Liang <kan.liang@intel.com>
Cc: "acme@kernel.org" <acme@kernel.org>,
"a.p.zijlstra@chello.nl" <a.p.zijlstra@chello.nl>,
"eranian@google.com" <eranian@google.com>,
"andi@firstfloor.org" <andi@firstfloor.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH V2 1/6] perf,core: allow invalid context events to be part of sw/hw groups
Date: Thu, 16 Apr 2015 17:43:57 +0100 [thread overview]
Message-ID: <20150416164356.GD19775@leverpostej> (raw)
In-Reply-To: <20150416163140.GA19775@leverpostej>
> Even if you ignore the fundamental semantics of groups, there are other
> problems with allowing shared contexts:
>
> * The *_txn functions only get called on the group leader's PMU. If your
> system PMU has these functions, they are not called.
>
> * Event rotation is per ctx, but now you could have some events in a CPU
> PMU's context, and some in the uncore PMU's context. So those can race
> with each other.
>
> * Throttling is also per-context. So those can race with each other too.
There's also a break down of behaviour: events in the uncore context
will get migrated to another CPU in the event of a hot unplug, while
events that are grouped with CPU events (and hence live in the CPU
context) will be destroyed.
Mark.
next prev parent reply other threads:[~2015-04-16 16:44 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-04-15 7:56 [PATCH V2 1/6] perf,core: allow invalid context events to be part of sw/hw groups Kan Liang
2015-04-15 7:56 ` [PATCH V2 2/6] perf evsel: Set evsel->cpus to the evlist->cpus when not constrained Kan Liang
2015-04-15 7:56 ` [PATCH V2 3/6] perf,tools: get real cpu id for print_aggr Kan Liang
2015-04-15 7:56 ` [PATCH V2 4/6] perf,tools: check and re-organize evsel cpu maps Kan Liang
2015-04-16 16:33 ` Mark Rutland
2015-04-15 7:56 ` [PATCH V2 5/6] perf,tools: open/mmap event uses event's cpu map Kan Liang
2015-04-15 7:56 ` [PATCH V2 6/6] perf/x86/intel/uncore: do not implicitly set uncore event cpu Kan Liang
2015-04-16 16:36 ` Mark Rutland
2015-04-15 16:15 ` [PATCH V2 1/6] perf,core: allow invalid context events to be part of sw/hw groups Peter Zijlstra
2015-04-15 16:21 ` Andi Kleen
2015-04-15 16:55 ` Peter Zijlstra
2015-04-15 17:28 ` Peter Zijlstra
2015-04-16 14:53 ` Liang, Kan
2015-04-16 16:31 ` Mark Rutland
2015-04-16 16:43 ` Mark Rutland [this message]
2015-04-16 17:16 ` Mark Rutland
2015-04-16 21:23 ` Andi Kleen
2015-04-17 9:47 ` Mark Rutland
2015-04-18 0:47 ` Andi Kleen
2015-04-20 10:15 ` Mark Rutland
2015-04-20 16:57 ` Andi Kleen
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