It becomes regular for application to request a big chunk of memory and do the sub-allocation by itself. I agree Kernel should do better to provide fine grained paging granularity. I don't know whether 1/2 of vram is the biggest single allocation application would like to do, but it is better if we can remove this limitation in the future as well. Thanks. Best Regards, David -----Original Message----- From: Zhou, David(ChunMing) Sent: Wednesday, August 17, 2016 9:58 AM To: Zhou, David(ChunMing) <David1.Zhou at amd.com>; Kuehling, Felix <Felix.Kuehling at amd.com>; Christian König <deathsimple at vodafone.de>; Marek Olšák <maraeo at gmail.com>; amd-gfx at lists.freedesktop.org; Mao, David <David.Mao at amd.com> Subject: RE: Random short freezes due to TTM buffer migrations Add his email. > -----Original Message----- > From: amd-gfx [mailto:amd-gfx-bounces at lists.freedesktop.org] On Behalf > Of Zhou, David(ChunMing) > Sent: Wednesday, August 17, 2016 9:57 AM > To: Kuehling, Felix <Felix.Kuehling at amd.com>; Christian König > <deathsimple at vodafone.de>; Marek Olšák <maraeo at gmail.com>; amd- > gfx at lists.freedesktop.org > Subject: RE: Random short freezes due to TTM buffer migrations > > +David Mao, > > Well, our Vulcan stack aslo encountered this problem before, the > performance is very low when migration is often. At that moment, we > want to add some algorithm for eviction LRU, but failed to find an > appropriate generic way. Then UMD decreased some VRAM usage at last. > Hope we can get a solution for full VRAM usage this time. > > Regards, > David Zhou > > > -----Original Message----- > > From: amd-gfx [mailto:amd-gfx-bounces at lists.freedesktop.org] On > > Behalf Of Felix Kuehling > > Sent: Wednesday, August 17, 2016 2:34 AM > > To: Christian König <deathsimple at vodafone.de>; Marek Olšák > > <maraeo at gmail.com>; amd-gfx at lists.freedesktop.org > > Subject: Re: Random short freezes due to TTM buffer migrations > > > > Very nice. I'm looking forward to this for KFD as well. > > > > One question: Will it be possible to share these split BOs as dmabufs? > > > > Regards, > > Felix > > > > > > On 16-08-16 11:27 AM, Christian König wrote: > > > Hi Marek, > > > > > > I'm already working on this. > > > > > > My current approach is to use a custom BO manager for VRAM with > > > TTM and so split allocations into chunks of 4MB. > > > > > > Large BOs are still swapped out as one, but it makes it much more > > > likely to that you can allocate 1/2 of VRAM as one buffer. > > > > > > Give me till the end of the week to finish this and then we can > > > test if that's sufficient or if we need to do more. > > > > > > Regards, > > > Christian. > > > > > > Am 16.08.2016 um 16:33 schrieb Marek Olšák: > > >> Hi, > > >> > > >> I'm seeing random temporary freezes (up to 2 seconds) under > > >> memory pressure. Before I describe the exact circumstances, I'd > > >> like to say that this is a serious issue affecting playability of > > >> certain AAA Linux games. > > >> > > >> In order to reproduce this, an application should: > > >> - allocate a few very large buffers (256-512 MB per buffer) > > >> - allocate more memory than there is available VRAM. The issue > > >> also occurs (but at a lower frequency) if the app needs only 80% of VRAM. > > >> > > >> Example: ttm_bo_validate needs to migrate a 512 MB buffer. The > > >> total size of moved memory for that call can be as high as 1.5 GB. > > >> This is always followed by a big temporary drop in VRAM usage. > > >> > > >> The game I'm testing needs 3.4 GB of VRAM. > > >> > > >> Setups: > > >> Tonga - 2 GB: It's nearly unplayable, because freezes occur too often. > > >> Fiji - 4 GB: There is one freeze at the beginning (which is > > >> annoying too), after that it's smooth. > > >> > > >> So even 4 GB is not enough. > > >> > > >> Workarounds: > > >> - Split buffers into smaller pieces in the kernel. It's not > > >> necessary to manage memory at page granularity (64KB). Splitting > > >> buffers into 16MB-large pieces might not be optimal but it would > > >> be a significant improvement. > > >> - Or do the same in Mesa. This would prevent inter-process and > > >> inter-API buffer sharing for split buffers (DRI, OpenCL), but we > > >> would at least verify how much the situation improves. > > >> > > >> Other issues sharing the same cause: > > >> - Allocations requesting 1/3 or more VRAM have a high chance of > > >> failing. It's generally not possible to allocate 1/2 or more VRAM > > >> as one buffer. > > >> > > >> Comments welcome, > > >> > > >> Marek > > >> _______________________________________________ > > >> amd-gfx mailing list > > >> amd-gfx at lists.freedesktop.org > > >> https://lists.freedesktop.org/mailman/listinfo/amd-gfx > > > > > > > > > _______________________________________________ > > > amd-gfx mailing list > > > amd-gfx at lists.freedesktop.org > > > https://lists.freedesktop.org/mailman/listinfo/amd-gfx > > > > _______________________________________________ > > amd-gfx mailing list > > amd-gfx at lists.freedesktop.org > > https://lists.freedesktop.org/mailman/listinfo/amd-gfx > _______________________________________________ > amd-gfx mailing list > amd-gfx at lists.freedesktop.org > https://lists.freedesktop.org/mailman/listinfo/amd-gfx
