On Thu, Dec 10, 2015 at 11:51:29AM +0000, Morton, Derek J wrote: > > > > > >-----Original Message----- > >From: Daniel Vetter [mailto:daniel.vetter@xxxxxxxx] On Behalf Of Daniel Vetter > >Sent: Thursday, December 10, 2015 10:13 AM > >To: Morton, Derek J > >Cc: intel-gfx@xxxxxxxxxxxxxxxxxxxxx; Wood, Thomas > >Subject: Re: [PATCH i-g-t] gem_flink_race/prime_self_import: Improve test reliability > > > >On Tue, Dec 08, 2015 at 12:44:44PM +0000, Derek Morton wrote: > >> gem_flink_race and prime_self_import have subtests which read the > >> number of open gem objects from debugfs to determine if objects have > >> leaked during the test. However the test can fail sporadically if the > >> number of gem objects changes due to other process activity. > >> This patch introduces a change to check the number of gem objects > >> several times to filter out any fluctuations. > > > >Why exactly does this happen? IGT tests should be run on bare metal, > >with everything else killed/subdued/shutup. If there's still things > >going on that create objects, we need to stop them from doing that. > > > >If this only applies to Android, or some special Android deamon them > >imo check for that at runtime and igt_skip("your setup is invalid, > >deamon %s running\n"); is the correct fix. After all just because you > >sampled for a bit doesn't mean that it wont still change right when you > >start running the test for real, so this is still fragile. > > Before running tests on android we do stop everything possible. I > suspect the culprit is coreu getting automatically restarted after it is > stopped. I had additional debug while developing this patch and what I > saw was the system being mostly quiescent but with some very low level > background activity. 1 extra object being created and then deleted > occasionally. Depending on whether it occurred at the start or end of > the test it was resulting in a reported leak of either 1 or -1 objects. > The patch fixes that issue by taking several samples and requiring them > to be the same, therefore filtering out the low level background noise. > It would not help if something in the background allocated an object and > kept it allocated, but I have not seen that happen. I only saw once the > object count increasing for 2 consecutive reads hence the count to 4 to > give a margin. The test was failing about 10%. With this patch I got > 100% pass across 300 runs of each of the tests. Hm, piglit checks that there's no other drm clients running. Have you tried re-running that check to zero in on the culprit? > If you are concerned about the behaviour when running the test with a > load of background activity I could add code to limit to the reset of > the count and fail the test in that instance. That would give a benefit > of distinguishing a test fail due to excessive background activity from > a detected leak. I'm also concerned for the overhead this causes everyone else. If this really is some Android trouble then I think it'd be good to only compile this on Android. But would still be much better if you can get to a reliably clean test environment. > I would not want to just have the test skip as that introduces a hole in > our test coverage. > > >Also would be good to extract get_stable_obj_count to a proper igt > >library function, if it indeed needs to be this tricky. And then add > >the explanation for why we need this in the gtkdoc. > > I can move the code to an igt library. Which library would you suggest? Igt_debugfs ? Hm yeah, it's a bit the dumping ground for all things debugfs access ;-) -Daniel -- Daniel Vetter Software Engineer, Intel Corporation http://blog.ffwll.ch _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx http://lists.freedesktop.org/mailman/listinfo/intel-gfx
