linux-kernel - Re: [PATCH] perf: Fix intel shared extra msr allocation

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Date:	Thu, 07 Jun 2012 12:01:08 +0800
From:	"Yan, Zheng" <zheng.z.yan@...el.com>
To:	Stephane Eranian <eranian@...gle.com>
CC:	Peter Zijlstra <peterz@...radead.org>,
	"Yan, Zheng" <zheng.z.yan@...ux.intel.com>,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] perf: Fix intel shared extra msr allocation

On 06/06/2012 06:12 PM, Stephane Eranian wrote:
> There is something wrong with this patch, I instrumented the code
> and I can see:
> [ 1377.324575] 1. idx=1 reg_idx=1 ref=-1 config=0xff01 era->config=0xff01
>                                                    ^^^^^^
> The test case on WSM (RSP0, RSP1):
> 
> $ perf stat  -a -C13 -e
> offcore_response_1:dmnd_data_rd,offcore_response_1:dmnd_data_rd sleep
> 100 &
> $ perf stat -a -C1 -e offcore_response_1:dmnd_rfo sleep 1
> 
> I think this happens during scheduling of the events, i.e., during the
> run and not on initial
> programming. That could happen with cgroups, for instance.
> 
The bug is in intel_fixup_er(), it should be:

static void intel_fixup_er(struct perf_event *event, int idx)
{
        if (idx == EXTRA_REG_RSP_0) {
                event->hw.config &= ~INTEL_ARCH_EVENT_MASK;
                event->hw.config |= 0x01b7;
                event->hw.extra_reg.idx = EXTRA_REG_RSP_0;
                event->hw.extra_reg.reg = MSR_OFFCORE_RSP_0;
        } else if (idx == EXTRA_REG_RSP_1) {
                event->hw.config &= ~INTEL_ARCH_EVENT_MASK;
                event->hw.config |= 0x01bb;
                event->hw.extra_reg.idx = EXTRA_REG_RSP_1;
                event->hw.extra_reg.reg = MSR_OFFCORE_RSP_1;
        }
}

Regards
Yan, Zheng
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