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08fb97de03
When many entities are competing for the same run queue on the same scheduler, we observe an unusually long wait times and some jobs get starved. This has been observed on GPUVis. The issue is due to the Round Robin policy used by schedulers to pick up the next entity's job queue for execution. Under stress of many entities and long job queues within entity some jobs could be stuck for very long time in it's entity's queue before being popped from the queue and executed while for other entities with smaller job queues a job might execute earlier even though that job arrived later then the job in the long queue. Fix: Add FIFO selection policy to entities in run queue, chose next entity on run queue in such order that if job on one entity arrived earlier then job on another entity the first job will start executing earlier regardless of the length of the entity's job queue. v2: Switch to rb tree structure for entities based on TS of oldest job waiting in the job queue of an entity. Improves next entity extraction to O(1). Entity TS update O(log N) where N is the number of entities in the run-queue Drop default option in module control parameter. v3: Various cosmetical fixes and minor refactoring of fifo update function. (Luben) v4: Switch drm_sched_rq_select_entity_fifo to in order search (Luben) v5: Fix up drm_sched_rq_select_entity_fifo loop (Luben) v6: Add missing drm_sched_rq_remove_fifo_locked v7: Fix ts sampling bug and more cosmetic stuff (Luben) v8: Fix module parameter string (Luben) Cc: Luben Tuikov <luben.tuikov@amd.com> Cc: Christian König <christian.koenig@amd.com> Cc: Direct Rendering Infrastructure - Development <dri-devel@lists.freedesktop.org> Cc: AMD Graphics <amd-gfx@lists.freedesktop.org> Signed-off-by: Andrey Grodzovsky <andrey.grodzovsky@amd.com> Tested-by: Yunxiang Li (Teddy) <Yunxiang.Li@amd.com> Signed-off-by: Luben Tuikov <luben.tuikov@amd.com> Reviewed-by: Luben Tuikov <luben.tuikov@amd.com> Link: https://patchwork.freedesktop.org/patch/msgid/20220930041258.1050247-1-luben.tuikov@amd.com |
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