linux-kernel - Re: [RFC PATCH V2 0/6] perf: Intel uncore pmu counting support

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Message-ID: <4F966AB5.4010909@intel.com>
Date:	Tue, 24 Apr 2012 16:56:21 +0800
From:	"Yan, Zheng" <zheng.z.yan@...el.com>
To:	Stephane Eranian <eranian@...gle.com>
CC:	a.p.zijlstra@...llo.nl, mingo@...e.hu, andi@...stfloor.org,
	linux-kernel@...r.kernel.org, ming.m.lin@...el.com,
	Jiri Olsa <jolsa@...hat.com>
Subject: Re: [RFC PATCH V2 0/6] perf: Intel uncore pmu counting support

On 04/23/2012 11:21 PM, Stephane Eranian wrote:
> Hi,
> 
> [+jolsa as it may have something to do with the event parser]
> 
> I started testing this on my NHM desktop machine, and I ran into the following
> problem:
> $ perf stat -a -C 0 -e uncore_nhm/CLOCKTICKS/,cycles,ref-cycles  --
> taskset -c 0 noploop 1
> noploop for 1 seconds
>  Performance counter stats for 'taskset -c 0 noploop 1':
>      3,435,695,848 cycles                    #    0.000 GHz
>          [100.00%]
>      2,803,309,845 ref-cycles
>      2,410,926,590 pmu
>        1.001391268 seconds time elapsed
> 
> First here, the cmdline event order is not respected. uncore events
> appear at the end. That's not very
> intuitive. Especially when you know that they all show up as 'pmu'. In
> other words, you cannot figure
> out what each value represents.
> 
> $ sudo perf stat -a -C 0 -e uncore_nhm/CLOCKTICKS/  -- taskset -c 0 noploop 1
> noploop for 1 seconds
>  Performance counter stats for 'taskset -c 0 noploop 1':
>      2,410,862,301 pmu
>        1.001393218 seconds time elapsed
> 
> That looks like the right value, well, minus the 'pmu' event name. But
> that's a different problem.
> 
> But then, the pathological case:
> 
> $ sudo perf stat -a -C 0 -e
> uncore_nhm/CLOCKTICKS/,uncore_nhm/QMC_NORMAL_READS_ANY/  -- taskset -c
> 0 noploop 1
> noploop for 1 seconds
>  Performance counter stats for 'taskset -c 0 noploop 1':
>             10,705 pmu
>        1.001395772 seconds time elapsed
> 
> If you pass more than one uncore event, all but the last one are
> suppressed from the output.
> It does not happen with core PMU events.
> 
> Looks like something may be wrong in the way the parser adds uncore events.
> 
> 
Thank you very much for pointing out this. I will try changing the flex and
bison input files to generate reentrant parser. I hope it can solve all these
issues.

Regards
Yan, Zheng

> On Sun, Apr 1, 2012 at 3:41 AM, Yan, Zheng <zheng.z.yan@...el.com> wrote:
>> Hi, all
>>
>> Here is the RFC patches to add uncore counting support for Nehalem,
>> Sandy Bridge and Sandy Bridge-EP, applied on top of current tip.
>> The code is based on Lin Ming's old patches.
>>
>> For Nehalem and Sandy Bridge-EP, A few general events are exported
>> under directory:
>> /sys/bus/event_source/devices/uncore_xxx/events/
>>
>> You can use 'perf stat' to access to the uncore pmu. For example:
>> perf stat -a -C 0 -e 'uncore_nhm/QMC_WRITES_FULL_ANY/' sleep 1
>>
>> Any comment is appreciated.
>> Thank you
>>
>> ---
>> Changes since v1:
>>  - Modify perf tool to parse events from sysfs
>>  - A few minor code cleanup
>>

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