linux-kernel - Re: [PATCH v3] perf stat: Show percore counts in per CPU output

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Date:   Thu, 13 Feb 2020 18:50:56 +0530
From:   Ravi Bangoria <ravi.bangoria@...ux.ibm.com>
To:     Jin Yao <yao.jin@...ux.intel.com>
Cc:     acme@...nel.org, jolsa@...nel.org, peterz@...radead.org,
        mingo@...hat.com, alexander.shishkin@...ux.intel.com,
        Linux-kernel@...r.kernel.org, ak@...ux.intel.com,
        kan.liang@...el.com, yao.jin@...el.com,
        Ravi Bangoria <ravi.bangoria@...ux.ibm.com>
Subject: Re: [PATCH v3] perf stat: Show percore counts in per CPU output

Hi Jin,

On 2/13/20 12:45 PM, Jin Yao wrote:
> With this patch, for example,
> 
>   # perf stat -e cpu/event=cpu-cycles,percore/ -a -A --percore-show-thread  -- sleep 1
> 
>    Performance counter stats for 'system wide':
> 
>   CPU0               2,453,061      cpu/event=cpu-cycles,percore/
>   CPU1               1,823,921      cpu/event=cpu-cycles,percore/
>   CPU2               1,383,166      cpu/event=cpu-cycles,percore/
>   CPU3               1,102,652      cpu/event=cpu-cycles,percore/
>   CPU4               2,453,061      cpu/event=cpu-cycles,percore/
>   CPU5               1,823,921      cpu/event=cpu-cycles,percore/
>   CPU6               1,383,166      cpu/event=cpu-cycles,percore/
>   CPU7               1,102,652      cpu/event=cpu-cycles,percore/
> 
> We can see counts are duplicated in CPU pairs
> (CPU0/CPU4, CPU1/CPU5, CPU2/CPU6, CPU3/CPU7).
> 

I was trying this patch and I am getting bit weird results when any cpu
is offline. Ex,

   $ lscpu | grep list
   On-line CPU(s) list:             0-4,6,7
   Off-line CPU(s) list:            5

   $ sudo ./perf stat -e cpu/event=cpu-cycles,percore/ -a -A --percore-show-thread -vv -- sleep 1
     ...
   cpu/event=cpu-cycles,percore/: 0: 23746491 1001189836 1001189836
   cpu/event=cpu-cycles,percore/: 1: 19802666 1001291299 1001291299
   cpu/event=cpu-cycles,percore/: 2: 24211983 1001394318 1001394318
   cpu/event=cpu-cycles,percore/: 3: 54051396 1001516816 1001516816
   cpu/event=cpu-cycles,percore/: 4: 6378825 1001064048 1001064048
   cpu/event=cpu-cycles,percore/: 5: 21299840 1001166297 1001166297
   cpu/event=cpu-cycles,percore/: 6: 13075410 1001274535 1001274535
   
    Performance counter stats for 'system wide':
   
   CPU0              30,125,316      cpu/event=cpu-cycles,percore/
   CPU1              19,802,666      cpu/event=cpu-cycles,percore/
   CPU2              45,511,823      cpu/event=cpu-cycles,percore/
   CPU3              67,126,806      cpu/event=cpu-cycles,percore/
   CPU4              30,125,316      cpu/event=cpu-cycles,percore/
   CPU7              67,126,806      cpu/event=cpu-cycles,percore/
   CPU0              30,125,316      cpu/event=cpu-cycles,percore/
   
          1.001918764 seconds time elapsed

I see proper result without --percore-show-thread:

   $ sudo ./perf stat -e cpu/event=cpu-cycles,percore/ -a -A -vv -- sleep 1
     ...
   cpu/event=cpu-cycles,percore/: 0: 11676414 1001190709 1001190709
   cpu/event=cpu-cycles,percore/: 1: 39119617 1001291459 1001291459
   cpu/event=cpu-cycles,percore/: 2: 41821512 1001391158 1001391158
   cpu/event=cpu-cycles,percore/: 3: 46853730 1001492799 1001492799
   cpu/event=cpu-cycles,percore/: 4: 14448274 1001095948 1001095948
   cpu/event=cpu-cycles,percore/: 5: 42238217 1001191187 1001191187
   cpu/event=cpu-cycles,percore/: 6: 33129641 1001292072 1001292072
   
    Performance counter stats for 'system wide':
   
   S0-D0-C0             26,124,688      cpu/event=cpu-cycles,percore/
   S0-D0-C1             39,119,617      cpu/event=cpu-cycles,percore/
   S0-D0-C2             84,059,729      cpu/event=cpu-cycles,percore/
   S0-D0-C3             79,983,371      cpu/event=cpu-cycles,percore/
   
          1.001961563 seconds time elapsed

[...]

> +--percore-show-thread::
> +The event modifier "percore" has supported to sum up the event counts
> +for all hardware threads in a core and show the counts per core.
> +
> +This option with event modifier "percore" enabled also sums up the event
> +counts for all hardware threads in a core but show the sum counts per
> +hardware thread. This is essentially a replacement for the any bit and
> +convenient for posting process.

s/posting process/post processing/ ? :)

Ravi