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Re: [PATCH v2 2/2] convert: Stream from fd to required clean filter instead of mmap

From
Jeff King <peff@peff.net>
Date
Aug 17, 2014, 07:27 UTC
Message-ID
<20140817072746.GD23808@peff.net>
In-Reply-To
<FA3F1197-25C5-42E4-9418-1C821D430819@zib.de>
On Sat, Aug 16, 2014 at 06:26:08PM +0200, Steffen Prohaska wrote:
Show 7 quoted lines
> > Is the 15MB limit supposed to be imposed somewhere or is it just a guide
> > of how much memory we expect Git to use in this scenario?
> 
> The test should confirm that the the file that is added is not mmapped
> to memory.  The process size should be relatively small independently
> of the size of the file that is added.  I wanted to keep the file size
> small.  The chosen sizes worked for me on Mac and Linux.

Measuring memory usage seems inherently a bit flaky for the test suite. It's also a little out of place, as the test suite is generally about correctness and outcomes, and this is a performance issue.

Would it make more sense to construct a t/perf test that shows off the change? I suppose the run-time change may not be that impressive, but it would be cool if t/perf could measure max memory use, too. Then we can just compare results between versions, which is enough to detect regressions.

There's some prior art in the jk/pack-bitmap-reuse-deltas series (which is not merged), where I taught it to measure output sizes of commands. That should provide the necessary refactoring base, I think.

-Peff
Previous: Andreas SchwabNext: Steffen Prohaska
Message 9 of 13 in “Stream fd to clean filter”
  1. 0/2 Stream fd to clean filterSteffen Prohaska, Aug 6, 2014
  2. 1/2 convert: Refactor would_convert_to_git() to single arg 'path'Steffen Prohaska, Aug 6, 2014
  3. 2/2 convert: Stream from fd to required clean filter instead of mmapSteffen Prohaska, Aug 6, 2014
  4. John KeepingAug 16, 2014
  5. Steffen ProhaskaAug 16, 2014
  6. Andreas SchwabAug 16, 2014
  7. Steffen ProhaskaAug 17, 2014
  8. Andreas SchwabAug 17, 2014
  9. Jeff KingAug 17, 2014
  10. Steffen ProhaskaAug 17, 2014
  11. Duy NguyenAug 17, 2014
  12. Jeff KingAug 19, 2014
  13. Steffen ProhaskaAug 19, 2014

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