linux-kernel - Re: [PATCH 1/4] perf/x86/cqm,mbm: Store cqm,mbm count for all events when RMID is recycled

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Date:	Mon, 25 Apr 2016 11:20:35 +0200
From:	Peter Zijlstra <peterz@...radead.org>
To:	Vikas Shivappa <vikas.shivappa@...ux.intel.com>
Cc:	tony.luck@...el.com, ravi.v.shankar@...el.com,
	fenghua.yu@...el.com, vikas.shivappa@...el.com, x86@...nel.org,
	linux-kernel@...r.kernel.org, hpa@...or.com, tglx@...utronix.de,
	mingo@...nel.org, h.peter.anvin@...el.com
Subject: Re: [PATCH 1/4] perf/x86/cqm,mbm: Store cqm,mbm count for all events
 when RMID is recycled

On Fri, Apr 22, 2016 at 05:27:18PM -0700, Vikas Shivappa wrote:
> During RMID recycling, when an event loses the RMID we saved the counter
> for group leader but it was not being saved for all the events in an
> event group. This would lead to a situation where if 2 perf instances
> are counting the same PID one of them would not see the updated count
> which other perf instance is seeing. This patch tries to fix the issue
> by saving the count for all the events in the same event group.


> @@ -486,14 +495,21 @@ static u32 intel_cqm_xchg_rmid(struct perf_event *group, u32 rmid)
>  	 * If our RMID is being deallocated, perform a read now.
>  	 */
>  	if (__rmid_valid(old_rmid) && !__rmid_valid(rmid)) {
>  
> +		rr = __init_rr(old_rmid, group->attr.config, 0);
>  		cqm_mask_call(&rr);
>  		local64_set(&group->count, atomic64_read(&rr.value));
> +		list_for_each_entry(event, head, hw.cqm_group_entry) {
> +			if (event->hw.is_group_event) {
> +
> +				evttype = event->attr.config;
> +				rr = __init_rr(old_rmid, evttype, 0);
> +
> +				cqm_mask_call(&rr);
> +					local64_set(&event->count,
> +						    atomic64_read(&rr.value));

Randomly indent much?

> +			}
> +		}
>  	}