Ok, I have sent a series of four patches that address Ben´s and Damien´s comments, plus a fix for a typo I found in gem_*_reloc. I have left out the igt_drop_caches_set() call inside gem_quiescent_gpu() because it is still being disputed, but I could easily include this patch as well. IMHO, gem_quiescent_gpu() does need the drop cache call, otherwise it doesn´t really do what it advertises. However, calling gem_quiescent_gpu() inside get_object_count() is probably overkill, and could potentially mask something going wrong (not so much when called at the beginning of a subtest, but definitely when called at the end!). What do you think? > -----Original Message----- > From: Daniel Vetter [mailto:daniel.vetter@xxxxxxxx] On Behalf Of Daniel > Vetter > Sent: Friday, November 01, 2013 7:08 PM > To: Ben Widawsky > Cc: Daniel Vetter; Mateo Lozano, Oscar; intel-gfx@xxxxxxxxxxxxxxxxxxxxx > Subject: Re: [PATCH] prime_self_import: Assure no pending > requests before object counting > > On Fri, Nov 01, 2013 at 11:52:48AM -0700, Ben Widawsky wrote: > > On Fri, Nov 01, 2013 at 07:47:37PM +0100, Daniel Vetter wrote: > > > On Fri, Nov 01, 2013 at 11:44:40AM -0700, Ben Widawsky wrote: > > > > On Fri, Nov 01, 2013 at 07:42:59PM +0100, Daniel Vetter wrote: > > > > > On Fri, Nov 01, 2013 at 09:18:51AM -0700, Ben Widawsky wrote: > > > > > > On Fri, Nov 01, 2013 at 05:08:17PM +0100, Daniel Vetter wrote: > > > > > > > On Fri, Nov 01, 2013 at 12:53:42PM +0000, oscar.mateo@xxxxxxxxx > wrote: > > > > > > > > From: Oscar Mateo <oscar.mateo@xxxxxxxxx> > > > > > > > > > > > > > > > > We don't want a previously used object to be freed in the > > > > > > > > middle of a before/after object counting operation (or we > > > > > > > > would get a "-1 objects leaked" message). We have seen > > > > > > > > this happening, e.g., when a context from a previous run > > > > > > > > dies, but its backing object is alive waiting for a retire_work to > kick in. > > > > > > > > > > > > > > > > Signed-off-by: Oscar Mateo <oscar.mateo@xxxxxxxxx> > > > > > > > > Cc: Ben Widawsky <ben@xxxxxxxxxxxx> > > > > > > > > > > > > > > Nice catch. Should we do this in general as part of our > > > > > > > gem_quiescent_gpu helper? All i-g-t testcase are written > > > > > > > under the assumption that they completel own the gpu and > > > > > > > that the gtt is completely empty besides the few > > > > > > > driver-allocated and pinned objects. So trying really hard to get rid > of any residual stuff sounds like a good idea. > > > > > > > > > > > > I was going to address this in the other mail thread.... in > > > > > > any case, I think not. I believe a separate helper is the way > > > > > > to go, and we should only call it when we absolutely want to. > > > > > > > > > > > > Though it's not the intention, I've seen many tests fail > > > > > > because of previous state, and I don't want to miss out on > > > > > > those in the future. It would also slow down the run unnecessarily > further. > > > > > > > > > > We already do rather eregious stuff in quiescent. So I want hard > > > > > numbers on your claim that it slows down stuff further - there > > > > > really shouldn't be much at all to retire/evict. > > > > > -Daniel > > > > > > > > I don't like any of those arbitrary calls to quiescent either fwiw. > > > > > > > > Can't I make the same demand for data BEFORE we merge the patch > > > > that it doesn't slow anything down? > > > > > > All those "arbitrary calls to quiescent" actually fixed spurious igt > > > failures. igts are written under the assumption that _nothing_ else > > > is going on in gpu-land, since otherwise it's just impossible to hit > > > some races. So this is matter of correctness first and speed second. > > > -Daniel > > > > They should be called where there are "spurious" errors and have an > > understanding why it's required to do. Sprinkling synchronizing code > > all over the place and calling it a fix is false. It's a "workaround" > > at best, but more likely dearth of time to do it properly. I can live > > with either honestly. I can't live with the statement that it's the > > proper thing to do. > > > > Very few tests we have will actually care that _nothing_ else is > > running, and if they do, annotations in code via quiescent calls is a > > nice way to document it. > > Atm a call to quiescent_gpu on an idle machine takes roughly 25us (in a loop > of 100k, snb laptop). You're optimizing the wrong thing. > > Also, as long as everyone bitches and moans about igt tests being unstable > I'm leaning _massively_ towards stable tests results. And I've really seen too > many igt tests fail spuriously so that I've decided to go back to an > unconditional to quiescent_gpu (it wasn't like that originally). > -Daniel > -- > Daniel Vetter > Software Engineer, Intel Corporation > +41 (0) 79 365 57 48 - http://blog.ffwll.ch _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx http://lists.freedesktop.org/mailman/listinfo/intel-gfx
