From: Peter Zijlstra <peterz@infradead•org>
To: Sukadev Bhattiprolu <sukadev@linux•vnet.ibm.com>
Cc: Ingo Molnar <mingo@redhat•com>,
Arnaldo Carvalho de Melo <acme@kernel•org>,
Michael Ellerman <mpe@ellerman•id.au>,
linux-kernel@vger•kernel.org, linuxppc-dev@lists•ozlabs.org,
linux-s390@vger•kernel.org, sparclinux@vger•kernel.org
Subject: Re: [PATCH v3 7/8] perf: Define PMU_TXN_READ interface
Date: Wed, 22 Jul 2015 07:55:03 +0200 [thread overview]
Message-ID: <20150722055503.GO25159@twins.programming.kicks-ass.net> (raw)
In-Reply-To: <20150722015045.GA24420@us.ibm.com>
On Tue, Jul 21, 2015 at 06:50:45PM -0700, Sukadev Bhattiprolu wrote:
> We are trying to use the following interface:
>
> start_txn(pmu, PERF_PMU_TXN_READ);
>
> perf_event_read(leader);
> list_for_each(sibling, &leader->sibling_list, group_entry)
> perf_event_read(sibling)
>
> pmu->commit_txn(pmu);
>
> with the idea that the PMU driver would save the type of transaction in
> ->start_txn() and use in ->read() and ->commit_txn().
>
> But since ->start_txn() and the ->read() operations could happen on different
> CPUs (perf_event_read() uses the event->oncpu to schedule a call), the PMU
> driver cannot use a per-cpu variable to save the state in ->start_txn().
> or is there better way?
I've not woken up yet, and not actually fully read the email, but can
you stuff the entire above chunk inside the IPI?
I think you could then actually optimize __perf_event_read() as well,
because all these events should be on the same context, so no point in
calling update_*time*() for every event or so.
next prev parent reply other threads:[~2015-07-22 5:55 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-07-15 3:01 [PATCH v3 0/8] Implement group-read of events using txn interface Sukadev Bhattiprolu
2015-07-15 3:01 ` [PATCH v3 1/8] powerpc/perf/hv-24x7: Whitespace - fix parameter alignment Sukadev Bhattiprolu
2015-08-03 1:35 ` [v3, " Michael Ellerman
2015-07-15 3:01 ` [PATCH v3 2/8] powerpc/perf/hv-24x7: Simplify extracting counter from result buffer Sukadev Bhattiprolu
2015-08-03 1:35 ` [v3, " Michael Ellerman
2015-07-15 3:01 ` [PATCH v3 3/8] perf: Add a flags parameter to pmu txn interfaces Sukadev Bhattiprolu
2015-07-16 20:17 ` Peter Zijlstra
2015-07-16 21:28 ` Sukadev Bhattiprolu
2015-07-16 20:48 ` Peter Zijlstra
2015-07-15 3:01 ` [PATCH v3 4/8] perf: Split perf_event_read() and perf_event_count() Sukadev Bhattiprolu
2015-07-15 3:01 ` [PATCH v3 5/8] perf: Split perf_event_read_value() Sukadev Bhattiprolu
2015-07-16 21:12 ` Peter Zijlstra
2015-07-16 21:41 ` Sukadev Bhattiprolu
2015-07-23 7:45 ` Peter Zijlstra
2015-07-27 5:54 ` Sukadev Bhattiprolu
2015-07-15 3:01 ` [PATCH v3 6/8] perf: Rename perf_event_read_{one, group}, perf_read_hw Sukadev Bhattiprolu
2015-07-15 3:01 ` [PATCH v3 7/8] perf: Define PMU_TXN_READ interface Sukadev Bhattiprolu
2015-07-16 22:20 ` Peter Zijlstra
2015-07-22 1:50 ` Sukadev Bhattiprolu
2015-07-22 5:55 ` Peter Zijlstra [this message]
2015-07-22 23:19 ` Sukadev Bhattiprolu
2015-07-23 8:04 ` Peter Zijlstra
2015-07-24 1:17 ` Sukadev Bhattiprolu
2015-07-15 3:01 ` [PATCH v3 8/8] powerpc/perf/hv-24x7: Use " Sukadev Bhattiprolu
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