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From: Peter Zijlstra <peterz@infradead.org>
To: Song Liu <songliubraving@fb.com>
Cc: Alexey Budankov <alexey.budankov@linux.intel.com>,
	Ingo Molnar <mingo@kernel.org>,
	lkml <linux-kernel@vger.kernel.org>,
	"acme@kernel.org" <acme@kernel.org>,
	Alexander Shishkin <alexander.shishkin@linux.intel.com>,
	Jiri Olsa <jolsa@redhat.com>,
	Stephane Eranian <eranian@google.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	"mark.rutland@arm.com" <mark.rutland@arm.com>,
	"megha.dey@intel.com" <megha.dey@intel.com>,
	"frederic@kernel.org" <frederic@kernel.org>
Subject: Re: [RFC][PATCH] perf: Rewrite core context handling
Date: Wed, 17 Oct 2018 20:33:10 +0200	[thread overview]
Message-ID: <20181017183310.GB2603@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <20181017171955.GQ3121@hirez.programming.kicks-ass.net>

On Wed, Oct 17, 2018 at 07:19:55PM +0200, Peter Zijlstra wrote:
> On Wed, Oct 17, 2018 at 04:43:27PM +0000, Song Liu wrote:
> 
> > > That makes task and cpu contexts wildly different, which will complicate
> > > matters I feel.
> > > 
> > 
> > I think we only need different logic when adding events to the task/cpu 
> > contexts. The ctx_sched_in() and ctx_sched_out() will need some extra
> > logic to filter out events that are not being scheduled (don't schedule
> > events on PMU-a when rotating PMU-b). This logic will be the same for 
> > task and cpu context. The difference is, the CPU context will not have
> > such events, because we never added such event to CPU context. 
> > 
> > Does this make sense? I could try draft a RFC to see how difficult it is. 
> 
> I'm not sure it saves much, if we have multiple per-cpu contexts we get
> to re-introduce the active_ctx_list and loose the simplification for the
> online status.
> 
> Plus that fundamental assymetry -- which would bother my OCD forever
> more :-)

Worse, the whole syscall that installs the events will come apart. The
locking for the two cases is different :/

  reply	other threads:[~2018-10-17 18:33 UTC|newest]

Thread overview: 38+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-10-10 10:45 [RFC][PATCH] perf: Rewrite core context handling Peter Zijlstra
2018-10-11  7:50 ` Song Liu
2018-10-11  9:29   ` Peter Zijlstra
2018-10-11 22:37     ` Song Liu
2018-10-12  9:50       ` Peter Zijlstra
2018-10-12 14:25         ` Peter Zijlstra
2018-10-13  8:31         ` Song Liu
2018-10-16  9:50           ` Peter Zijlstra
2018-10-16 16:34             ` Song Liu
2018-10-16 18:10               ` Peter Zijlstra
2018-10-16 18:24                 ` Song Liu
2018-10-12  7:04     ` Alexey Budankov
2018-10-12 11:54       ` Peter Zijlstra
2018-10-15  7:26 ` Alexey Budankov
2018-10-15  8:34   ` Peter Zijlstra
2018-10-15  8:53     ` Peter Zijlstra
2018-10-15 17:29     ` Alexey Budankov
2018-10-15 18:31       ` Stephane Eranian
2018-10-16  6:39         ` Alexey Budankov
2018-10-16  9:32         ` Peter Zijlstra
2018-10-15 22:09     ` Song Liu
2018-10-16 18:28       ` Song Liu
2018-10-17 11:06         ` Peter Zijlstra
2018-10-17 16:43           ` Song Liu
2018-10-17 17:19             ` Peter Zijlstra
2018-10-17 18:33               ` Peter Zijlstra [this message]
2018-10-17 18:57                 ` Song Liu
2018-10-16 16:26 ` Mark Rutland
2018-10-16 18:07   ` Peter Zijlstra
2018-10-17  8:57 ` Alexey Budankov
2018-10-17 15:01   ` Alexander Shishkin
2018-10-17 15:58     ` Alexey Budankov
2018-10-17 16:30   ` Peter Zijlstra
2018-10-18  7:05     ` Alexey Budankov
2018-10-22 13:26 ` Alexander Shishkin
2018-10-23  6:13 ` Song Liu
2018-10-23  6:55   ` Peter Zijlstra
2019-05-15 11:17 ` Alexander Shishkin

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