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Tue, 16 Apr 2024 13:24:51 +0000 Message-ID: Date: Tue, 16 Apr 2024 15:24:45 +0200 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2 0/9] TTM shrinker helpers and xe buffer object shrinker To: =?UTF-8?Q?Thomas_Hellstr=C3=B6m?= , intel-xe@lists.freedesktop.org Cc: Somalapuram Amaranath , dri-devel@lists.freedesktop.org, Matthew Brost , "Kuehling, Felix" References: <20240416100730.6666-1-thomas.hellstrom@linux.intel.com> Content-Language: en-US From: =?UTF-8?Q?Christian_K=C3=B6nig?= In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-ClientProxiedBy: FR3P281CA0023.DEUP281.PROD.OUTLOOK.COM (2603:10a6:d10:1c::7) To PH7PR12MB5685.namprd12.prod.outlook.com (2603:10b6:510:13c::22) MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: PH7PR12MB5685:EE_|DM4PR12MB8499:EE_ X-MS-Office365-Filtering-Correlation-Id: 12661bfd-f688-4a75-6b70-08dc5e18985e X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0; 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In other words >> that >> ttm_resource_manager_next() takes only the cursor as argument, adding >> ttm_resource_cursor_fini()/ttm_resource_cursor_fini_locked() as one >> patch and then ttm_lru_bulk_move_init()/ttm_lru_bulk_move_fini() as >> second. > Yes, I can take a look at that. I think the shortening of the argument > list of ttm_resource_manager_next() makes sense as a separate cleanup. > > The other two are needed because of the changes introduced in the > respective patches. I could of course add stubs of these functions > before the patch that currently introduce them if needed, but don't > really see the point. What do you think. Na, stubs doesn't make sense. I was under the expression that you would have something to do for them even without the LRU patch. If that's not the case then just skip that. > >> With that done I think we should first switch over TTM and all >> drivers >> using it to drm_exec as part of it's context object. > So are you ok with adding an optional drm_exec pointer in the > ttm_operation_ctx for this? (That was my plan moving forward). Yeah, perfectly valid. My thinking was just to do that first. > > However, when that has been added, I think it makes sense to leave to > the driver author to port their validation loops and bo allocation over > to using drm_exec. While we made sure the drm_exec object was indeed > passed to the validation helper in the drm_gpuvm code, I'm not sure > everybody actually includes their validation and bo allocation (for > example page-table-bos) in their drm_exec while_not_all_locked() loop, > and I think it's reasonable to require the "port the driver over" to be > an optional but strongly recommended driver effort. If the driver sets > ctx->drm_exec to NULL, it will fallback to current behaviour. For the intermediate case I think it makes sense to have this optional, but in the long run we should make it mandatory. > >> Then I would switch over to using LRU hitches for both swapping and >> eviction. >> >> And when that's finally done we can take a look into the partial >> shmem >> swapping :) >> >> And Felix is really (and mean *really*) looking forward to the >> partial >> shmem swapping as well. > While the LRU walker helper introduced in patch 8 has drm_exec support, > shrinkers don't require it, since they are always trylocking. (However > being able to "evict" system to swap directly in the validation stage > using drm_exec locking is probably something we should support). > > That's why I opted for implementing shrinking before exhaustive > eviction. But if you insist we can do it the other way around. Most of > what's needed is already in the patches. I don't care about the order in which things are implemented, but I think we should have at least some eviction prototype as well for testing. Eviction is just the much easier to exercise use case. Regards, Christian. > > /Thomas > > >> Regards, >> Christian. >> >> Am 16.04.24 um 12:07 schrieb Thomas Hellström: >>> This series implements TTM shrinker / eviction helpers and an xe bo >>> shrinker. It builds on two previous series, *and obsoletes these*. >>> First >>> >>> https://www.mail-archive.com/dri-devel@lists.freedesktop.org/msg484425.html >>> >>> for patch 1-4, which IMO still could be reviewed and pushed as a >>> separate series. >>> >>> Second the previous TTM shrinker series >>> >>> https://lore.kernel.org/linux-mm/b7491378-defd-4f1c-31e2-29e4c77e2d67@amd.com/T/ >>> >>> Where the comment about layering >>> https://lore.kernel.org/linux-mm/b7491378-defd-4f1c-31e2-29e4c77e2d67@amd.com/T/#ma918844aa8a6efe8768fdcda0c6590d5c93850c9 >>> >>> now addressed, and this version also implements shmem objects for >>> backup >>> rather than direct swap-cache insertions, which was used in the >>> previuos >>> series. It turns out that with per-page backup / shrinking, shmem >>> objects >>> appears to work just as well as direct swap-cache insertions with >>> the >>> added benefit that was introduced in the previous TTM shrinker >>> series to >>> avoid running out of swap entries isn't really needed. >>> >>> In any case, patch 1-4 are better described in their separate >>> series. >>> (RFC is removed for those). >>> >>> Patch 5 could in theory be skipped but introduces a possibility to >>> easily >>> add or test multiple backup backends, like the direct swap-cache >>> insertion or even files into fast dedicated nvme storage for for >>> example. >>> >>> Patch 6 introduces helpers in the ttm_pool code for page-by-page >>> shrinking >>> and recovery. It avoids having to temporarily allocate a huge >>> amount of >>> memory to be able to shrink a buffer object. It also introduces the >>> possibility to immediately write-back pages if needed, since that >>> tends >>> to be a bit delayed when left to kswapd. >>> >>> Patch 7 Adds a simple error injection to the above code to help >>> increase >>> test coverage. >>> >>> Patch 8 introduces a LRU walk helper for eviction and shrinking. >>> It's >>> currently xe-only but not xe-specific and can easily be moved to >>> TTM when >>> used by more than one driver or when eviction is implemented using >>> it. >>> >>> Patch 9 introduces a helper callback for shrinking (Also ready to >>> be >>> moved to TTM) and an xe-specific shrinker implementation. It also >>> adds a kunit test to test the shrinker functionality by trying to >>> allocate twice the available amount of RAM as buffer objects. If >>> there >>> is no swap-space available, the buffer objects are marked >>> purgeable. >>> >>> v2: >>> - Squash obsolete revision history in the patch commit messages. >>> - Fix a couple of review comments by Christian >>> - Don't store the mem_type in the TTM managers but in the >>>    resource cursor. >>> - Rename introduced TTM *back_up* function names to *backup* >>> - Add ttm pool recovery fault injection. >>> - Shrinker xe kunit test >>> - Various bugfixes >>> >>> Cc: Somalapuram Amaranath >>> Cc: Christian König >>> Cc: >>> >>> Thomas Hellström (8): >>>    drm/ttm: Allow TTM LRU list nodes of different types >>>    drm/ttm: Use LRU hitches >>>    drm/ttm, drm/amdgpu, drm/xe: Consider hitch moves within bulk >>> sublist >>>      moves >>>    drm/ttm: Allow continued swapout after -ENOSPC falure >>>    drm/ttm: Add a virtual base class for graphics memory backup >>>    drm/ttm/pool: Provide a helper to shrink pages. >>>    drm/xe, drm/ttm: Provide a generic LRU walker helper >>>    drm/xe: Add a shrinker for xe bos >>> >>>   drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c |   4 + >>>   drivers/gpu/drm/ttm/Makefile           |   2 +- >>>   drivers/gpu/drm/ttm/ttm_backup_shmem.c | 137 +++++++++ >>>   drivers/gpu/drm/ttm/ttm_bo.c           |   1 + >>>   drivers/gpu/drm/ttm/ttm_device.c       |  33 ++- >>>   drivers/gpu/drm/ttm/ttm_pool.c         | 391 >>> ++++++++++++++++++++++++- >>>   drivers/gpu/drm/ttm/ttm_resource.c     | 231 ++++++++++++--- >>>   drivers/gpu/drm/ttm/ttm_tt.c           |  34 +++ >>>   drivers/gpu/drm/xe/Makefile            |   2 + >>>   drivers/gpu/drm/xe/xe_bo.c             | 123 ++++++-- >>>   drivers/gpu/drm/xe/xe_bo.h             |   3 + >>>   drivers/gpu/drm/xe/xe_device.c         |   8 + >>>   drivers/gpu/drm/xe/xe_device_types.h   |   2 + >>>   drivers/gpu/drm/xe/xe_shrinker.c       | 237 +++++++++++++++ >>>   drivers/gpu/drm/xe/xe_shrinker.h       |  18 ++ >>>   drivers/gpu/drm/xe/xe_ttm_helpers.c    | 224 ++++++++++++++ >>>   drivers/gpu/drm/xe/xe_ttm_helpers.h    |  63 ++++ >>>   drivers/gpu/drm/xe/xe_vm.c             |   4 + >>>   include/drm/ttm/ttm_backup.h           | 136 +++++++++ >>>   include/drm/ttm/ttm_device.h           |   2 + >>>   include/drm/ttm/ttm_pool.h             |   4 + >>>   include/drm/ttm/ttm_resource.h         |  96 +++++- >>>   include/drm/ttm/ttm_tt.h               |  19 ++ >>>   23 files changed, 1683 insertions(+), 91 deletions(-) >>>   create mode 100644 drivers/gpu/drm/ttm/ttm_backup_shmem.c >>>   create mode 100644 drivers/gpu/drm/xe/xe_shrinker.c >>>   create mode 100644 drivers/gpu/drm/xe/xe_shrinker.h >>>   create mode 100644 drivers/gpu/drm/xe/xe_ttm_helpers.c >>>   create mode 100644 drivers/gpu/drm/xe/xe_ttm_helpers.h >>>   create mode 100644 include/drm/ttm/ttm_backup.h >>>