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25d851adbf
If we couple the scheduler more tightly with the execlists policy, we can apply the preemption policy to the question of whether we need to kick the tasklet at all for this priority bump. v2: Rephrase it as a core i915 policy and not an execlists foible. v3: Pull the kick together. Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk> Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com> Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com> Link: https://patchwork.freedesktop.org/patch/msgid/20190507122544.12698-1-chris@chris-wilson.co.uk
73 lines
2.2 KiB
C
73 lines
2.2 KiB
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_SCHEDULER_H_
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#define _I915_SCHEDULER_H_
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#include <linux/bitops.h>
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#include <linux/list.h>
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#include <linux/kernel.h>
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#include "i915_scheduler_types.h"
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#define priolist_for_each_request(it, plist, idx) \
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for (idx = 0; idx < ARRAY_SIZE((plist)->requests); idx++) \
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list_for_each_entry(it, &(plist)->requests[idx], sched.link)
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#define priolist_for_each_request_consume(it, n, plist, idx) \
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for (; \
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(plist)->used ? (idx = __ffs((plist)->used)), 1 : 0; \
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(plist)->used &= ~BIT(idx)) \
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list_for_each_entry_safe(it, n, \
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&(plist)->requests[idx], \
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sched.link)
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void i915_sched_node_init(struct i915_sched_node *node);
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bool __i915_sched_node_add_dependency(struct i915_sched_node *node,
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struct i915_sched_node *signal,
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struct i915_dependency *dep,
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unsigned long flags);
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int i915_sched_node_add_dependency(struct i915_sched_node *node,
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struct i915_sched_node *signal);
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void i915_sched_node_fini(struct i915_sched_node *node);
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void i915_schedule(struct i915_request *request,
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const struct i915_sched_attr *attr);
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void i915_schedule_bump_priority(struct i915_request *rq, unsigned int bump);
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struct list_head *
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i915_sched_lookup_priolist(struct intel_engine_cs *engine, int prio);
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void __i915_priolist_free(struct i915_priolist *p);
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static inline void i915_priolist_free(struct i915_priolist *p)
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{
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if (p->priority != I915_PRIORITY_NORMAL)
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__i915_priolist_free(p);
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}
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static inline bool i915_scheduler_need_preempt(int prio, int active)
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{
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/*
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* Allow preemption of low -> normal -> high, but we do
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* not allow low priority tasks to preempt other low priority
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* tasks under the impression that latency for low priority
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* tasks does not matter (as much as background throughput),
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* so kiss.
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*
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* More naturally we would write
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* prio >= max(0, last);
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* except that we wish to prevent triggering preemption at the same
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* priority level: the task that is running should remain running
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* to preserve FIFO ordering of dependencies.
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*/
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return prio > max(I915_PRIORITY_NORMAL - 1, active);
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}
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#endif /* _I915_SCHEDULER_H_ */
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