From: "tip-bot2 for Pierre Gondois" <tip-bot2@linutronix.de>
To: linux-tip-commits@vger.kernel.org
Cc: Xuewen Yan <xuewen.yan@unisoc.com>,
Pierre Gondois <Pierre.Gondois@arm.com>,
"Peter Zijlstra (Intel)" <peterz@infradead.org>,
Lukasz Luba <lukasz.luba@arm.com>,
Dietmar Eggemann <dietmar.eggemann@arm.com>,
Vincent Donnefort <vincent.donnefort@arm.com>,
x86@kernel.org, linux-kernel@vger.kernel.org
Subject: [tip: sched/core] sched/fair: Only compute base_energy_pd if necessary
Date: Wed, 12 May 2021 10:28:32 -0000 [thread overview]
Message-ID: <162081531212.29796.16374133225445038112.tip-bot2@tip-bot2> (raw)
In-Reply-To: <20210504090743.9688-2-Pierre.Gondois@arm.com>
The following commit has been merged into the sched/core branch of tip:
Commit-ID: 8d4c97c105ca0735b0d972d1025cb150a7008451
Gitweb: https://git.kernel.org/tip/8d4c97c105ca0735b0d972d1025cb150a7008451
Author: Pierre Gondois <Pierre.Gondois@arm.com>
AuthorDate: Tue, 04 May 2021 10:07:42 +01:00
Committer: Peter Zijlstra <peterz@infradead.org>
CommitterDate: Wed, 12 May 2021 11:43:23 +02:00
sched/fair: Only compute base_energy_pd if necessary
find_energy_efficient_cpu() searches the best energy CPU
to place a task on. To do so, the energy of each performance domain
(pd) is computed w/ and w/o the task placed on it.
The energy of a pd w/o the task (base_energy_pd) is computed prior
knowing whether a CPU is available in the pd.
Move the base_energy_pd computation after looping through the CPUs
of a pd and only compute it if at least one CPU is available.
Suggested-by: Xuewen Yan <xuewen.yan@unisoc.com>
Signed-off-by: Pierre Gondois <Pierre.Gondois@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Lukasz Luba <lukasz.luba@arm.com>
Reviewed-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Reviewed-by: Vincent Donnefort <vincent.donnefort@arm.com>
Link: https://lkml.kernel.org/r/20210504090743.9688-2-Pierre.Gondois@arm.com
---
kernel/sched/fair.c | 41 ++++++++++++++++++++++++-----------------
1 file changed, 24 insertions(+), 17 deletions(-)
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index d10c6cc..b229d0c 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -6687,13 +6687,10 @@ static int find_energy_efficient_cpu(struct task_struct *p, int prev_cpu)
for (; pd; pd = pd->next) {
unsigned long cur_delta, spare_cap, max_spare_cap = 0;
+ bool compute_prev_delta = false;
unsigned long base_energy_pd;
int max_spare_cap_cpu = -1;
- /* Compute the 'base' energy of the pd, without @p */
- base_energy_pd = compute_energy(p, -1, pd);
- base_energy += base_energy_pd;
-
for_each_cpu_and(cpu, perf_domain_span(pd), sched_domain_span(sd)) {
if (!cpumask_test_cpu(cpu, p->cpus_ptr))
continue;
@@ -6714,25 +6711,35 @@ static int find_energy_efficient_cpu(struct task_struct *p, int prev_cpu)
if (!fits_capacity(util, cpu_cap))
continue;
- /* Always use prev_cpu as a candidate. */
if (cpu == prev_cpu) {
- prev_delta = compute_energy(p, prev_cpu, pd);
- prev_delta -= base_energy_pd;
- best_delta = min(best_delta, prev_delta);
- }
-
- /*
- * Find the CPU with the maximum spare capacity in
- * the performance domain
- */
- if (spare_cap > max_spare_cap) {
+ /* Always use prev_cpu as a candidate. */
+ compute_prev_delta = true;
+ } else if (spare_cap > max_spare_cap) {
+ /*
+ * Find the CPU with the maximum spare capacity
+ * in the performance domain.
+ */
max_spare_cap = spare_cap;
max_spare_cap_cpu = cpu;
}
}
- /* Evaluate the energy impact of using this CPU. */
- if (max_spare_cap_cpu >= 0 && max_spare_cap_cpu != prev_cpu) {
+ if (max_spare_cap_cpu < 0 && !compute_prev_delta)
+ continue;
+
+ /* Compute the 'base' energy of the pd, without @p */
+ base_energy_pd = compute_energy(p, -1, pd);
+ base_energy += base_energy_pd;
+
+ /* Evaluate the energy impact of using prev_cpu. */
+ if (compute_prev_delta) {
+ prev_delta = compute_energy(p, prev_cpu, pd);
+ prev_delta -= base_energy_pd;
+ best_delta = min(best_delta, prev_delta);
+ }
+
+ /* Evaluate the energy impact of using max_spare_cap_cpu. */
+ if (max_spare_cap_cpu >= 0) {
cur_delta = compute_energy(p, max_spare_cap_cpu, pd);
cur_delta -= base_energy_pd;
if (cur_delta < best_delta) {
next prev parent reply other threads:[~2021-05-12 10:30 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-05-04 9:07 [PATCH v3 0/2] sched/fair: find_energy_efficient_cpu() enhancements Pierre Gondois
2021-05-04 9:07 ` [PATCH v3 1/2] sched/fair: Only compute base_energy_pd if necessary Pierre Gondois
2021-05-12 10:28 ` tip-bot2 for Pierre Gondois [this message]
2021-05-04 9:07 ` [PATCH v3 2/2] sched/fair: Fix negative energy delta in find_energy_efficient_cpu() Pierre Gondois
2021-05-12 10:28 ` [tip: sched/core] " tip-bot2 for Pierre Gondois
2021-05-04 9:10 ` [PATCH v3 0/2] sched/fair: find_energy_efficient_cpu() enhancements Pierre Gondois
2021-05-04 11:49 ` Xuewen Yan
2021-05-04 9:59 ` Peter Zijlstra
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=162081531212.29796.16374133225445038112.tip-bot2@tip-bot2 \
--to=tip-bot2@linutronix.de \
--cc=Pierre.Gondois@arm.com \
--cc=dietmar.eggemann@arm.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-tip-commits@vger.kernel.org \
--cc=lukasz.luba@arm.com \
--cc=peterz@infradead.org \
--cc=vincent.donnefort@arm.com \
--cc=x86@kernel.org \
--cc=xuewen.yan@unisoc.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).