Re: [PATCH] perf_events: fix bug in hw_perf_enable()

[Stephane Eranian]

On Mon, Feb 1, 2010 at 5:45 PM, Peter Zijlstra <peterz@xxxxxxxxxxxxx> wrote:
> On Mon, 2010-02-01 at 17:14 +0100, Stephane Eranian wrote:
>
>> Using perfmon on Core 2 on a 10s noploop:
>>
>> pfmon -eunhalted_reference_cycles,unhalted_core_cycles,cpu_clk_unhalted:bus
>> Ânoploop 10
>> noploop for 10 seconds
>> 23869090125 UNHALTED_REFERENCE_CYCLES
>> 23849336873 UNHALTED_CORE_CYCLES
>> Â2652122099 CPU_CLK_UNHALTED:BUS
>
> Weird, I used:
>
> Âwhile :; do :; done &
> Âwhile :; do :; done &
> Âwhile :; do :; done &
> Âwhile :; do :; done &
> Âperf stat -a -e r013c -e r013c sleep 4
> Âkillall bash
>
> Which gives:
>
> ÂPerformance counter stats for 'sleep 4':
>
> Â244235699509090 Âraw 0x13c
> Â244235695558036 Âraw 0x13c
>
Strange. I am running mine on a Q6600.
What's yours?

> Â Â4.005485333 Âseconds time elapsed
>
> And verified it used fixed counter 2 and general purpose counter 0 using
> sysrq-p.
>
> [523417.108402] CPU#0: Â gen-PMC0 ctrl: Â000000000053013c
> [523417.108403] CPU#0: Â gen-PMC0 count: 000000ff80019948
> [523417.108405] CPU#0: Â gen-PMC0 left: Â000000007fffffff
> [523417.108407] CPU#0: Â gen-PMC1 ctrl: Â0000000000000000
> [523417.108409] CPU#0: Â gen-PMC1 count: 0000000000000000
> [523417.108411] CPU#0: Â gen-PMC1 left: Â000000007fffb8a8
> [523417.108412] CPU#0: fixed-PMC0 count: 0000000000000000
> [523417.108414] CPU#0: fixed-PMC1 count: 0000000000000000
> [523417.108416] CPU#0: fixed-PMC2 count: 0000010db1db2117
>
> Using -linus, since that doesn't have any of the recent constraint
> patches in that would avoid us from using fixed-PMC2.
>
>



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Stephane Eranian  | EMEA Software Engineering
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