From: Byungchul Park <byungchul.park@lge.com>
To: <peterz@infradead.org>, <mingo@kernel.org>
Cc: <linux-kernel@vger.kernel.org>, <juri.lelli@gmail.com>,
<rostedt@goodmis.org>, <kernel-team@lge.com>
Subject: [PATCH v3 3/3] sched/rt: Add support for SD_PREFER_SIBLING on find_lowest_rq()
Date: Thu, 23 Mar 2017 11:12:49 +0900 [thread overview]
Message-ID: <1490235169-370-3-git-send-email-byungchul.park@lge.com> (raw)
In-Reply-To: <1490235169-370-1-git-send-email-byungchul.park@lge.com>
It would be better to avoid pushing tasks to other cpu within
a SD_PREFER_SIBLING domain, instead, get more chances to check other
siblings.
Signed-off-by: Byungchul Park <byungchul.park@lge.com>
---
kernel/sched/rt.c | 17 +++++++++++++++++
1 file changed, 17 insertions(+)
diff --git a/kernel/sched/rt.c b/kernel/sched/rt.c
index 979b734..6332b2ad 100644
--- a/kernel/sched/rt.c
+++ b/kernel/sched/rt.c
@@ -1624,6 +1624,7 @@ static int find_lowest_rq(struct task_struct *task)
struct cpumask *lowest_mask = this_cpu_cpumask_var_ptr(local_cpu_mask);
int this_cpu = smp_processor_id();
int cpu = task_cpu(task);
+ int fallback_cpu = -1;
/* Make sure the mask is initialized first */
if (unlikely(!lowest_mask))
@@ -1671,6 +1672,15 @@ static int find_lowest_rq(struct task_struct *task)
best_cpu = cpumask_first_and(lowest_mask,
sched_domain_span(sd));
if (best_cpu < nr_cpu_ids) {
+ /*
+ * If current domain is SD_PREFER_SIBLING
+ * flaged, we have to get more chances to
+ * check other siblings.
+ */
+ if (sd->flags & SD_PREFER_SIBLING) {
+ fallback_cpu = best_cpu;
+ continue;
+ }
rcu_read_unlock();
return best_cpu;
}
@@ -1679,6 +1689,13 @@ static int find_lowest_rq(struct task_struct *task)
rcu_read_unlock();
/*
+ * If fallback_cpu is valid, all our quesses failed *except* for
+ * SD_PREFER_SIBLING domain. Now, we can return the fallback cpu.
+ */
+ if (fallback_cpu != -1)
+ return fallback_cpu;
+
+ /*
* And finally, if there were no matches within the domains
* just give the caller *something* to work with from the compatible
* locations.
--
1.9.1
next prev parent reply other threads:[~2017-03-23 2:18 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-03-23 2:12 [PATCH v3 1/3] sched/deadline: Make find_later_rq() choose a closer cpu in topology Byungchul Park
2017-03-23 2:12 ` [PATCH v3 2/3] sched/deadline: Add support for SD_PREFER_SIBLING on find_later_rq() Byungchul Park
2017-03-23 2:12 ` Byungchul Park [this message]
2017-03-23 9:21 ` [PATCH v3 3/3] sched/rt: Add support for SD_PREFER_SIBLING on find_lowest_rq() Byungchul Park
2017-03-23 13:59 ` Steven Rostedt
2017-03-23 9:44 ` Peter Zijlstra
2017-03-23 10:36 ` Byungchul Park
2017-03-23 14:08 ` Steven Rostedt
2017-03-23 22:45 ` Byungchul Park
2017-03-27 14:33 ` [PATCH v3 1/3] sched/deadline: Make find_later_rq() choose a closer cpu in topology Juri Lelli
2017-03-28 0:04 ` Byungchul Park
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=1490235169-370-3-git-send-email-byungchul.park@lge.com \
--to=byungchul.park@lge.com \
--cc=juri.lelli@gmail.com \
--cc=kernel-team@lge.com \
--cc=linux-kernel@vger.kernel.org \
--cc=mingo@kernel.org \
--cc=peterz@infradead.org \
--cc=rostedt@goodmis.org \
/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).