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Commit1413b2bc07("drm/i915: Trim NEWCLIENT boosting") had the intended consequence of not allowing a sequence of work that merely crossed into a new engine the privilege to be promoted to NEWCLIENT status. It also had the unintended consequence of actually making NEWCLIENT effective on heavily oversubscribed transcode machines and impacting upon their throughput. If we consider a client packet composed of (rcsA, rcsB, vcs) and 30 of those clients, using the NEWCLIENT boost that will be scheduled as rcsA x 30, (rcsB, vcs) x 30 where as before it would have been (rcsA, rcsB, vcs) x 30 That is with NEWCLIENT only boosting the first request of each client, we would execute all rcsA requests prior to running on the vcs engines; acruing a lot of dead time as compared to the previous case where the vcs engine would be started in parallel to processing the second client. The previous patch has the effect of delaying submission until it is required by a third party (either the user with an explicit wait, or by another client/engine). We reduce the NEWCLIENT bump to a mere WAIT, which has the effect of removing its preemptive grant and reducing it to the same level as any other user interaction -- that it will not be promoted above the interengine dependencies, and so preventing NEWCLIENTS from starving other engines. This a large nerf to the rrul properties of the current NEWCLIENT, but it still does give prioritised submission to new requests from light workloads. References:b16c765122("drm/i915: Priority boost for new clients") Fixes:1413b2bc07("drm/i915: Trim NEWCLIENT boosting") # customer impact Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk> Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com> Cc: Dmitry Rogozhkin <dmitry.v.rogozhkin@intel.com> Cc: Dmitry Ermilov <dmitry.ermilov@intel.com> Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com> Link: https://patchwork.freedesktop.org/patch/msgid/20190515130052.4475-4-chris@chris-wilson.co.uk
41 lines
962 B
C
41 lines
962 B
C
/*
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* SPDX-License-Identifier: MIT
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*
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* Copyright © 2018 Intel Corporation
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*/
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#ifndef _I915_PRIOLIST_TYPES_H_
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#define _I915_PRIOLIST_TYPES_H_
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#include <linux/list.h>
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#include <linux/rbtree.h>
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#include <uapi/drm/i915_drm.h>
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enum {
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I915_PRIORITY_MIN = I915_CONTEXT_MIN_USER_PRIORITY - 1,
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I915_PRIORITY_NORMAL = I915_CONTEXT_DEFAULT_PRIORITY,
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I915_PRIORITY_MAX = I915_CONTEXT_MAX_USER_PRIORITY + 1,
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I915_PRIORITY_INVALID = INT_MIN
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};
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#define I915_USER_PRIORITY_SHIFT 2
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#define I915_USER_PRIORITY(x) ((x) << I915_USER_PRIORITY_SHIFT)
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#define I915_PRIORITY_COUNT BIT(I915_USER_PRIORITY_SHIFT)
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#define I915_PRIORITY_MASK (I915_PRIORITY_COUNT - 1)
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#define I915_PRIORITY_WAIT ((u8)BIT(0))
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#define I915_PRIORITY_NOSEMAPHORE ((u8)BIT(1))
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#define __NO_PREEMPTION (I915_PRIORITY_WAIT)
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struct i915_priolist {
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struct list_head requests[I915_PRIORITY_COUNT];
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struct rb_node node;
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unsigned long used;
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int priority;
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};
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#endif /* _I915_PRIOLIST_TYPES_H_ */
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