Re: [creduce-dev] halfempty algorithm for creduce?

[John Regehr <regehr@cs.utah.edu>]

Thanks Vegard! This is very useful to know.

I'll just add that the top-level result here, where C-Reduce produces a 
smaller final output, but takes longer to do it, is basically the entire 
point of C-Reduce. We spent a lot of effort making it aggressive, and 
quite a lot less effort making it fast.

John



On 6/14/19 12:37 AM, Vegard Nossum wrote:
> I did a creduce vs. halfempty benchmark at some point. These were my results:
>
> """
> Same input (739 bytes C++), ~same test script, 1 vs 32 threads (on 32 cores).
>
> Halfempty speedup = ~2.7 (-63%),
> creduce speedup = ~8.7 (-89%).
>
> at 32 cores the two programs were within 8 seconds of each other (!),
> whereas on 1 core, halfempty took 7m27 and creduce took 22m57
>
> The final file sizes were:
>
> 460 bytes for halfempty,
> 317 for c-reduce
> """
>
> File dump from back then at:
> https://gist.github.com/vegard/e79b96cefffbfb753da17c4646132fab
>
>
> Vegard
>
> On Thu, 13 Jun 2019 at 22:57, Nico Weber <thakis@chromium.org> wrote:
> > Hi,
> >
> > creduce often takes more than an hour to run, with most cores being idle. https://github.com/googleprojectzero/halfempty is an approach to doing delta debugging in parallel. Could that approach be implemented in creduce as well?
> >
> > Thanks,
> > Nico