Re: [FFmpeg-devel] [PATCH v2] tests/fate/vcodec: Limit mem alignment for vsynth..mpeg2-422 tests

[Soft Works <softworkz@hotmail.com>]

> -----Original Message-----
> From: ffmpeg-devel <ffmpeg-devel-bounces@ffmpeg.org> On Behalf Of
> Paul B Mahol
> Sent: Monday, May 30, 2022 11:07 AM
> To: FFmpeg development discussions and patches <ffmpeg-
> devel@ffmpeg.org>
> Subject: Re: [FFmpeg-devel] [PATCH v2] tests/fate/vcodec: Limit mem
> alignment for vsynth..mpeg2-422 tests
> 
> On Mon, May 30, 2022 at 10:35 AM Soft Works <softworkz@hotmail.com>
> wrote:
> 
> >
> >
> > > -----Original Message-----
> > > From: ffmpeg-devel <ffmpeg-devel-bounces@ffmpeg.org> On Behalf Of
> > > Anton Khirnov
> > > Sent: Monday, May 30, 2022 9:35 AM
> > > To: FFmpeg development discussions and patches <ffmpeg-
> > > devel@ffmpeg.org>
> > > Subject: Re: [FFmpeg-devel] [PATCH v2] tests/fate/vcodec: Limit
> mem
> > > alignment for vsynth..mpeg2-422 tests
> > >
> > > Quoting Soft Works (2022-05-28 15:17:54)
> > > > Do you have a better idea?
> > > >
> > > > The one advantage of this method is that you don’t need to
> change
> > > compilation parameters
> > > > nor  any source code. It’s only a runtime flag being set only
> for
> > > this specific family of tests.
> > >
> > > At the very least, I would expect the commit message to explain
> what
> > > exactly the problem is, and why is it fixed in this seemingly ad-
> hoc
> > > manner.
> > >
> > > "limit mem alignment to fix failing tests" explains nothing.
> >
> > BTW, that's not the actual commit message.
> > What I have submitted is this:
> >
> > ------------------------
> >
> > tests/fate/vcodec: Limit mem alignment for vsynth..mpeg2-422 tests
> >
> > The tests:
> >
> > - vsynth2-mpeg2-422
> > - vsynth1-mpeg2-422
> > - vsynth_lena-mpeg2-422
> >
> > were failing on newer CPUs where av_cpu_max_align() returns
> > values > 32. This patch sets cpuflags to disable avx512
> > extensions for those tests only.
> >
> > Signed-off-by: softworkz <softworkz@hotmail.com>
> >
> > ------------------------
> >
> > What do you want me to add to it?
> >
> >
> There appears a very large language barrier present here.
> 
> In that FATE thread I explicitly wrote that this or similar solutions

It's not similar but quite different to the one you commented on.

> are
> considered the hack.

Well, the test .mak files are full of hacks then, with the many super-
special flags in place that do not reflect any real world use at all.

That flag does nothing more than to assure that the tests are run
under the same conditions under which the ref files were generated.
Many other flags are used in tests for the same reason.
Anyway, this is about regression testing, not about annoying developers
(with later CPU models) by failing tests for months or years due
to a well-known problem.

Thanks,
sw



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