From: Peter Zijlstra <peterz@infradead.org>
To: mingo@kernel.org, vincent.guittot@linaro.org
Cc: linux-kernel@vger.kernel.org, peterz@infradead.org,
juri.lelli@redhat.com, dietmar.eggemann@arm.com,
rostedt@goodmis.org, bsegall@google.com, mgorman@suse.de,
bristot@redhat.com, corbet@lwn.net, qyousef@layalina.io,
chris.hyser@oracle.com, patrick.bellasi@matbug.net,
pjt@google.com, pavel@ucw.cz, qperret@google.com,
tim.c.chen@linux.intel.com, joshdon@google.com, timj@gnu.org,
kprateek.nayak@amd.com, yu.c.chen@intel.com,
youssefesmat@chromium.org, joel@joelfernandes.org, efault@gmx.de
Subject: [PATCH 16/17] [RFC] sched/eevdf: Minimal vavg option
Date: Tue, 28 Mar 2023 11:26:38 +0200 [thread overview]
Message-ID: <20230328110354.712296502@infradead.org> (raw)
In-Reply-To: 20230328092622.062917921@infradead.org
Alternative means of tracking min_vruntime to minimize the deltas
going into avg_vruntime -- note that because vavg move backwards this
is all sorts of tricky.
Also more expensive because of extra divisions... Not found this
convincing.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
---
kernel/sched/fair.c | 51 ++++++++++++++++++++++++++++--------------------
kernel/sched/features.h | 2 +
2 files changed, 32 insertions(+), 21 deletions(-)
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -732,28 +732,37 @@ static u64 __update_min_vruntime(struct
static void update_min_vruntime(struct cfs_rq *cfs_rq)
{
- struct sched_entity *se = __pick_first_entity(cfs_rq);
- struct sched_entity *curr = cfs_rq->curr;
-
- u64 vruntime = cfs_rq->min_vruntime;
-
- if (curr) {
- if (curr->on_rq)
- vruntime = curr->vruntime;
- else
- curr = NULL;
+ if (sched_feat(MINIMAL_VA)) {
+ u64 vruntime = avg_vruntime(cfs_rq);
+ s64 delta = (s64)(vruntime - cfs_rq->min_vruntime);
+
+ avg_vruntime_update(cfs_rq, delta);
+
+ u64_u32_store(cfs_rq->min_vruntime, vruntime);
+ } else {
+ struct sched_entity *se = __pick_first_entity(cfs_rq);
+ struct sched_entity *curr = cfs_rq->curr;
+
+ u64 vruntime = cfs_rq->min_vruntime;
+
+ if (curr) {
+ if (curr->on_rq)
+ vruntime = curr->vruntime;
+ else
+ curr = NULL;
+ }
+
+ if (se) {
+ if (!curr)
+ vruntime = se->vruntime;
+ else
+ vruntime = min_vruntime(vruntime, se->vruntime);
+ }
+
+ /* ensure we never gain time by being placed backwards. */
+ u64_u32_store(cfs_rq->min_vruntime,
+ __update_min_vruntime(cfs_rq, vruntime));
}
-
- if (se) {
- if (!curr)
- vruntime = se->vruntime;
- else
- vruntime = min_vruntime(vruntime, se->vruntime);
- }
-
- /* ensure we never gain time by being placed backwards. */
- u64_u32_store(cfs_rq->min_vruntime,
- __update_min_vruntime(cfs_rq, vruntime));
}
static inline bool __entity_less(struct rb_node *a, const struct rb_node *b)
--- a/kernel/sched/features.h
+++ b/kernel/sched/features.h
@@ -9,6 +9,8 @@ SCHED_FEAT(PLACE_FUDGE, true)
SCHED_FEAT(PLACE_DEADLINE_INITIAL, true)
SCHED_FEAT(PLACE_BONUS, false)
+SCHED_FEAT(MINIMAL_VA, false)
+
/*
* Prefer to schedule the task we woke last (assuming it failed
* wakeup-preemption), since its likely going to consume data we
next prev parent reply other threads:[~2023-03-28 11:08 UTC|newest]
Thread overview: 55+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-03-28 9:26 [PATCH 00/17] sched: EEVDF using latency-nice Peter Zijlstra
2023-03-28 9:26 ` [PATCH 01/17] sched: Introduce latency-nice as a per-task attribute Peter Zijlstra
2023-03-28 9:26 ` [PATCH 02/17] sched/fair: Add latency_offset Peter Zijlstra
2023-03-28 9:26 ` [PATCH 03/17] sched/fair: Add sched group latency support Peter Zijlstra
2023-03-28 9:26 ` [PATCH 04/17] sched/fair: Add avg_vruntime Peter Zijlstra
2023-03-28 23:57 ` Josh Don
2023-03-29 7:50 ` Peter Zijlstra
2023-04-05 19:13 ` Peter Zijlstra
2023-03-28 9:26 ` [PATCH 05/17] sched/fair: Remove START_DEBIT Peter Zijlstra
2023-03-28 9:26 ` [PATCH 06/17] sched/fair: Add lag based placement Peter Zijlstra
2023-04-03 9:18 ` Chen Yu
2023-04-05 9:47 ` Peter Zijlstra
2023-04-06 3:03 ` Chen Yu
2023-04-13 15:42 ` Chen Yu
2023-04-13 15:55 ` Chen Yu
2023-03-28 9:26 ` [PATCH 07/17] rbtree: Add rb_add_augmented_cached() helper Peter Zijlstra
2023-03-28 9:26 ` [PATCH 08/17] sched/fair: Implement an EEVDF like policy Peter Zijlstra
2023-03-29 1:26 ` Josh Don
2023-03-29 8:02 ` Peter Zijlstra
2023-03-29 8:06 ` Peter Zijlstra
2023-03-29 8:22 ` Peter Zijlstra
2023-03-29 18:48 ` Josh Don
2023-03-29 8:12 ` Peter Zijlstra
2023-03-29 18:54 ` Josh Don
2023-03-29 8:18 ` Peter Zijlstra
2023-03-29 14:35 ` Vincent Guittot
2023-03-30 8:01 ` Peter Zijlstra
2023-03-30 17:05 ` Vincent Guittot
2023-04-04 12:00 ` Peter Zijlstra
2023-03-28 9:26 ` [PATCH 09/17] sched: Commit to lag based placement Peter Zijlstra
2023-03-28 9:26 ` [PATCH 10/17] sched/smp: Use lag to simplify cross-runqueue placement Peter Zijlstra
2023-03-28 9:26 ` [PATCH 11/17] sched: Commit to EEVDF Peter Zijlstra
2023-03-28 9:26 ` [PATCH 12/17] sched/debug: Rename min_granularity to base_slice Peter Zijlstra
2023-03-28 9:26 ` [PATCH 13/17] sched: Merge latency_offset into slice Peter Zijlstra
2023-03-28 9:26 ` [PATCH 14/17] sched/eevdf: Better handle mixed slice length Peter Zijlstra
2023-03-31 15:26 ` Vincent Guittot
2023-04-04 9:29 ` Peter Zijlstra
2023-04-04 13:50 ` Joel Fernandes
2023-04-05 5:41 ` Mike Galbraith
2023-04-05 8:35 ` Peter Zijlstra
2023-04-05 20:05 ` Joel Fernandes
2023-04-14 11:18 ` Phil Auld
2023-04-16 5:10 ` Joel Fernandes
[not found] ` <20230401232355.336-1-hdanton@sina.com>
2023-04-02 2:40 ` Mike Galbraith
2023-03-28 9:26 ` [PATCH 15/17] [RFC] sched/eevdf: Sleeper bonus Peter Zijlstra
2023-03-29 9:10 ` Mike Galbraith
2023-03-28 9:26 ` Peter Zijlstra [this message]
2023-03-28 9:26 ` [PATCH 17/17] [DEBUG] sched/eevdf: Debug / validation crud Peter Zijlstra
2023-04-03 7:42 ` [PATCH 00/17] sched: EEVDF using latency-nice Shrikanth Hegde
2023-04-10 3:13 ` David Vernet
2023-04-11 2:09 ` David Vernet
[not found] ` <20230410082307.1327-1-hdanton@sina.com>
2023-04-11 10:15 ` Mike Galbraith
[not found] ` <20230411133333.1790-1-hdanton@sina.com>
2023-04-11 14:56 ` Mike Galbraith
[not found] ` <20230412025042.1413-1-hdanton@sina.com>
2023-04-12 4:05 ` Mike Galbraith
2023-04-25 12:32 ` Phil Auld
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