Adding cache misses and references to list of default events for perf stat?

Adding cache misses and references to list of default events for perf stat?

[Milian Wolff]

Hello all,

could we have the cache-references,cache-misses events added to the list of 
default events for perf stat? I think it is a very valuable metric for all 
user-space applications.

Currently, I run perf stat twice, once with the default events, and once with

perf stat -e cache-references,cache-misses ...

there is no easy way to append two events to the list of default events.

So, what do you think?

Bye
-- 
Milian Wolff
mail@milianw.de
http://milianw.de

Re: Adding cache misses and references to list of default events for perf stat?

[Andi Kleen]

Milian Wolff <mail@milianw.de> writes:

> Hello all,
>
> could we have the cache-references,cache-misses events added to the list of 
> default events for perf stat? I think it is a very valuable metric for all 
> user-space applications.
>
> Currently, I run perf stat twice, once with the default events, and once with
>
> perf stat -e cache-references,cache-misses ...
>
> there is no easy way to append two events to the list of default events.
>
> So, what do you think?

On most systems with only four counters it'll start multiplexing, which
will give much worse results. Defaulting to non multiplexing is much
better.

Reproducing the standard perf stat output isn't that difficult. It's 

perf stat -e task-clock,cs,migrations,page-faults,cycles,instructions,branches,branch-misses

and then add more events. If you remove the bogus stalled-* events you
have even two free counters.

If you exceed four you should define appropiate groups with {} 

-Andi
-- 
ak@linux.intel.com -- Speaking for myself only

Re: Adding cache misses and references to list of default events for perf stat?

[Namhyung Kim]

Hi Andi and Milian,

On Tue, 04 Nov 2014 12:16:25 -0800, Andi Kleen wrote:
> Milian Wolff <mail@milianw.de> writes:
>
>> Hello all,
>>
>> could we have the cache-references,cache-misses events added to the list of 
>> default events for perf stat? I think it is a very valuable metric for all 
>> user-space applications.
>>
>> Currently, I run perf stat twice, once with the default events, and once with
>>
>> perf stat -e cache-references,cache-misses ...
>>
>> there is no easy way to append two events to the list of default events.
>>
>> So, what do you think?
>
> On most systems with only four counters it'll start multiplexing, which
> will give much worse results. Defaulting to non multiplexing is much
> better.

Anyway it has -d/--detailed option which can be specified up to 3 times.

 # perf stat -ad sleep 1

 Performance counter stats for 'system wide':

       8021.100443      task-clock (msec)         #    8.013 CPUs utilized           [100.00%]
               574      context-switches          #    0.072 K/sec                   [100.00%]
                10      cpu-migrations            #    0.001 K/sec                   [100.00%]
                61      page-faults               #    0.008 K/sec                  
       153,639,037      cycles                    #    0.019 GHz                     [40.05%]
       223,846,109      stalled-cycles-frontend   #  145.70% frontend cycles idle    [40.14%]
       205,555,693      stalled-cycles-backend    #  133.79% backend  cycles idle    [40.15%]
       173,763,228      instructions              #    1.13  insns per cycle        
                                                  #    1.29  stalled cycles per insn [50.12%]
        34,553,334      branches                  #    4.308 M/sec                   [50.12%]
           410,018      branch-misses             #    1.19% of all branches         [50.02%]
        45,617,877      L1-dcache-loads           #    5.687 M/sec                   [49.93%]
         2,232,930      L1-dcache-load-misses     #    4.89% of all L1-dcache hits   [49.88%]
           563,164      LLC-loads                 #    0.070 M/sec                   [39.92%]
           240,780      LLC-load-misses           #   42.75% of all LL-cache hits    [39.92%]

       1.000997709 seconds time elapsed

Thanks,
Namhyung


>
> Reproducing the standard perf stat output isn't that difficult. It's 
>
> perf stat -e task-clock,cs,migrations,page-faults,cycles,instructions,branches,branch-misses
>
> and then add more events. If you remove the bogus stalled-* events you
> have even two free counters.
>
> If you exceed four you should define appropiate groups with {} 
>
> -Andi

Re: Adding cache misses and references to list of default events for perf stat?

[Milian Wolff]

On Wednesday 05 November 2014 11:26:36 Namhyung Kim wrote:
> Hi Andi and Milian,
> 
> On Tue, 04 Nov 2014 12:16:25 -0800, Andi Kleen wrote:
> > Milian Wolff <mail@milianw.de> writes:
> >> Hello all,
> >> 
> >> could we have the cache-references,cache-misses events added to the list
> >> of
> >> default events for perf stat? I think it is a very valuable metric for
> >> all
> >> user-space applications.
> >> 
> >> Currently, I run perf stat twice, once with the default events, and once
> >> with
> >> 
> >> perf stat -e cache-references,cache-misses ...
> >> 
> >> there is no easy way to append two events to the list of default events.
> >> 
> >> So, what do you think?
> > 
> > On most systems with only four counters it'll start multiplexing, which
> > will give much worse results. Defaulting to non multiplexing is much
> > better.
> 
> Anyway it has -d/--detailed option which can be specified up to 3 times.

Thanks, that helps!

Cheers

-- 
Milian Wolff
mail@milianw.de
http://milianw.de