Re: [PATCH i-g-t] scripts/trace.pl: Optimize event parsing and processing

[Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>]

On 20/12/2017 23:50, John Harrison wrote:
> On 12/20/2017 1:54 AM, Tvrtko Ursulin wrote:
>> What was the effect of all this on your big traces? I am only testing 
>> with a smaller one which goes from ~3.3s to ~2.2s. On a larger trace 
>> it might be non-linear gains due to double sort avoidance, unless 
>> there will be some other effects to cancel that out.
>>
> 
> So with a trace of a shortened gem_exec_nop/basic_sequential, the 'perf 
> script' output is 439MB and the original trace.pl before any of the 
> changes took ~180s. After the 'auto-detect field order' patch, it went 
> up to ~201s. With the optimisation patch it is down to ~129s.
> 
> However, I am also seeing differences in the HTML output since the 
> optimisation patch. The differences aren't massive, just slight 
> variations in the times. The structure is all the same, its just that 
> the accounting and/or time stamps are out.
> 
> For example:
>      {id: 1, content: 'Ring0<br><small><br>79.48% idle<br><br>34.32% 
> busy<br>584.97% runnable<br>2103.60% queued<br><br>16.18% 
> wait<br><br>200931 batches<br>331.28us avg batch<br>331.38us avg engine 
> batch<br></small>'},
> vs
>      {id: 1, content: 'Ring0<br><small><br>79.48% idle<br><br>34.32% 
> busy<br>584.97% runnable<br>2103.60% queued<br><br>16.18% 
> wait<br><br>200931 batches<br>338.56us avg batch<br>338.56us avg engine 
> batch<br></small>'},
> 
> Or:
>      {id: 58, key: -210383407,  type: 'range', group: 4, subgroup: 2, 
> subgroupOrder: 3, content: '428/3 <small>0</small> 
> <small><i>???</i></small> <small><i>++</i></small> <br>142us 
> <small>(0us)</small>', start: '2017-01-05 21:27:45.352968', end: 
> '2017-01-05 21:27:45.353110', style: 'color: white; background-color: 
> red;'},
> vs
>      {id: 58, key: -210383407,  type: 'range', group: 4, subgroup: 2, 
> subgroupOrder: 3, content: '428/3 <small>0</small> 
> <small><i>???</i></small> <small><i>++</i></small> <br>159us 
> <small>(0us)</small>', start: '2017-01-05 21:27:45.352968', end: 
> '2017-01-05 21:27:45.353127', style: 'color: white; background-color: 
> red;'},
> 
> I can send you the full output if it is useful and the source logs too. 
> The HTML output is about 840KB but as noted, the perf logs are hundreds 
> of MBs.

I was able to reproduce it. I think it's down to floating point 
mishandling. Neither the original nor the optimized version were correct 
and both are accumulating error. I'll send an updated patch shortly.

Regards,

Tvrtko
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