From: Song Liu <songliubraving@fb.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@kernel.org>,
lkml <linux-kernel@vger.kernel.org>,
"acme@kernel.org" <acme@kernel.org>,
"alexander.shishkin@linux.intel.com"
<alexander.shishkin@linux.intel.com>,
"jolsa@redhat.com" <jolsa@redhat.com>,
"eranian@google.com" <eranian@google.com>,
"tglx@linutronix.de" <tglx@linutronix.de>,
"alexey.budankov@linux.intel.com"
<alexey.budankov@linux.intel.com>,
"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: Tue, 16 Oct 2018 18:24:23 +0000 [thread overview]
Message-ID: <2228A2BE-E34C-4D8D-9271-8EE8A5C83121@fb.com> (raw)
In-Reply-To: <20181016181015.GD3121@hirez.programming.kicks-ass.net>
> On Oct 16, 2018, at 11:10 AM, Peter Zijlstra <peterz@infradead.org> wrote:
>
> On Tue, Oct 16, 2018 at 04:34:05PM +0000, Song Liu wrote:
>>>> 3. perf_event_pmu_context owns RB tree of events. Since we don't
>>>> need rotation across multiple hardware PMUs, the rotation is
>>>> within same perf_event_pmu_context.
>>>
>>> By keeping the RB trees in perf_event_context, we get bigger trees,
>>> which is more efficient (log(n+m) < log(n) + log(m))
>>>
>>> Also, specifically, it means we only need a single merge sort /
>>> iteration to schedule in a full context, instead of (again) doing 'n' of
>>> them.
>>>
>>> Also, given a context and a pmu, it is cheaper for finding the relevant
>>> events; this is needed for big.little for instance. Something the
>>> proposed patch doesn't fully flesh out.
>>
>> Would it be faster if we add a perf_event_pmu_context pointer to the
>> perf_event?
>
> + pmu_ctx = find_get_pmu_context(pmu, ctx, event);
> + if (IS_ERR(pmu_ctx)) {
> + err = PTR_ERR(pmu_ctx);
> + goto err_locked;
> + }
> + event->pmu_ctx = pmu_ctx;
>
> Like that?
Aha, we already have it. I misunderstood this one. Please ignore that.
Thanks,
Song
next prev parent reply other threads:[~2018-10-16 18:27 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 [this message]
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
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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