linux-kernel - Re: [PATCH 09/10] Define PERF_PMU_TXN

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Date:	Thu, 6 Aug 2015 14:10:29 +0200
From:	Peter Zijlstra <peterz@...radead.org>
To:	Sukadev Bhattiprolu <sukadev@...ux.vnet.ibm.com>
Cc:	Ingo Molnar <mingo@...hat.com>,
	Arnaldo Carvalho de Melo <acme@...nel.org>,
	Michael Ellerman <mpe@...erman.id.au>,
	linux-kernel@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org,
	linux-s390@...r.kernel.org, sparclinux@...r.kernel.org
Subject: Re: [PATCH 09/10] Define PERF_PMU_TXN_READ interface

On Sun, Jul 26, 2015 at 10:40:37PM -0700, Sukadev Bhattiprolu wrote:
> @@ -3743,7 +3762,13 @@ static u64 perf_event_aggregate(struct perf_event *event, u64 *enabled,
>  	lockdep_assert_held(&event->child_mutex);
>  
>  	list_for_each_entry(child, &event->child_list, child_list) {
> +#if 0
> +		/*
> +		 * TODO: Do we need this read() for group events on PMUs that
> +		 * 	 don't implement PERF_PMU_TXN_READ transactions?
> +		 */
>  		(void)perf_event_read(child, false);
> +#endif
>  		total += perf_event_count(child);
>  		*enabled += child->total_time_enabled;
>  		*running += child->total_time_running;

Aw gawd, I've been an idiot!!

I just realized this is a _CHILD_ loop, not a _SIBLING_ loop !!

We need to flip the loops in perf_read_group(), find attached two
patches that go on top of 1,2,4.

After this you can add the perf_event_read() return value (just fold
patches 6,8) after which you can do patch 10 (which has a broken
Subject fwiw).



View attachment "peterz-perf_event_read-group.patch" of type "text/plain" (3606 bytes)

View attachment "peterz-perf-invert-perf_read_group.patch" of type "text/plain" (3746 bytes)