linux-kernel - Re: [PATCH 09/10] perf, tools: Support DividedBy header in JSON event list

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Date:   Mon, 17 Oct 2016 11:28:04 -0700
From:   Andi Kleen <andi@...stfloor.org>
To:     Jiri Olsa <jolsa@...hat.com>
Cc:     Andi Kleen <andi@...stfloor.org>, acme@...nel.org,
        jolsa@...nel.org, sukadev@...ux.vnet.ibm.com, eranian@...gle.com,
        linux-kernel@...r.kernel.org, Andi Kleen <ak@...ux.intel.com>
Subject: Re: [PATCH 09/10] perf, tools: Support DividedBy header in JSON
 event list

> 
> so..
> 
> - you put 'DividedBy' into JSON event's defition any further
>   explanation how or why the format we use for event defs will
>   be used now used to describe ratios
> 
> - then you force perf stat to merge together all 'same' uncore events
>   to get just one number..

The ratios don't need that. They work fine without merging.
It's an independent feature.

The merging is just a convenience feature for some of the uncore pmus to make
the output much more readable. For example the cbox pmu is duplicated
for each core, and we have systems with 21 cores per socket now.

So without merging you end up with something like the output below.

The second variant is much more readable.

> 
> - then you display that ratio (just the number) in perf stat metrics output
>   without any explanation or description

The event name is already expressive enough. I find it fairly
straight forward that there is a ratio attached with a count.

> 
> I dont see that as a nicely fit, more like hack

I would call it a simple solution that works well.

I don't see any easy path for full scripting, and also I think
it would be vastly overengineered here needing a lot of 
infastructure that isn't really needed.


-Andi

% perf stat --no-merge -a  -e unc_c_llc_lookup.any sleep 1

 Performance counter stats for 'system wide':

           694,976 Bytes unc_c_llc_lookup.any                                        
           706,304 Bytes unc_c_llc_lookup.any                                        
           956,608 Bytes unc_c_llc_lookup.any                                        
           782,720 Bytes unc_c_llc_lookup.any                                        
           605,696 Bytes unc_c_llc_lookup.any                                        
           442,816 Bytes unc_c_llc_lookup.any                                        
           659,328 Bytes unc_c_llc_lookup.any                                        
           509,312 Bytes unc_c_llc_lookup.any                                        
           263,936 Bytes unc_c_llc_lookup.any                                        
           592,448 Bytes unc_c_llc_lookup.any                                        
           672,448 Bytes unc_c_llc_lookup.any                                        
           608,640 Bytes unc_c_llc_lookup.any                                        
           641,024 Bytes unc_c_llc_lookup.any                                        
           856,896 Bytes unc_c_llc_lookup.any                                        
           808,832 Bytes unc_c_llc_lookup.any                                        
           684,864 Bytes unc_c_llc_lookup.any                                        
           710,464 Bytes unc_c_llc_lookup.any                                        
           538,304 Bytes unc_c_llc_lookup.any                                        

       1.002577660 seconds time elapsed
 


% perf stat  -a  -e unc_c_llc_lookup.any sleep 1

 Performance counter stats for 'system wide':

         2,685,120 Bytes unc_c_llc_lookup.any                                        

       1.002648032 seconds time elapsed