From: Peter Oskolkov <posk@google.com>
To: Peter Zijlstra <peterz@infradead.org>,
mingo@redhat.com, tglx@linutronix.de, juri.lelli@redhat.com,
vincent.guittot@linaro.org, dietmar.eggemann@arm.com,
rostedt@goodmis.org, bsegall@google.com, mgorman@suse.de,
bristot@redhat.com
Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org,
linux-api@vger.kernel.org, x86@kernel.org, pjt@google.com,
posk@google.com, avagin@google.com, jannh@google.com,
tdelisle@uwaterloo.ca, posk@posk.io
Subject: [RFC PATCH v2 1/5] sched/umcg: add WF_CURRENT_CPU and externise ttwu
Date: Thu, 13 Jan 2022 15:39:36 -0800 [thread overview]
Message-ID: <20220113233940.3608440-2-posk@google.com> (raw)
In-Reply-To: <20220113233940.3608440-1-posk@google.com>
From: Peter Oskolkov <posk@posk.io>
Add WF_CURRENT_CPU wake flag that advices the scheduler to
move the wakee to the current CPU. This is useful for fast on-CPU
context switching use cases such as UMCG.
In addition, make ttwu external rather than static so that
the flag could be passed to it from outside of sched/core.c.
Signed-off-by: Peter Oskolkov <posk@google.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20211122211327.5931-2-posk@google.com
---
kernel/sched/core.c | 3 +--
kernel/sched/fair.c | 4 ++++
kernel/sched/sched.h | 15 +++++++++------
3 files changed, 14 insertions(+), 8 deletions(-)
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 83872f95a1ea..04525933de94 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -3980,8 +3980,7 @@ bool ttwu_state_match(struct task_struct *p, unsigned int state, int *success)
* Return: %true if @p->state changes (an actual wakeup was done),
* %false otherwise.
*/
-static int
-try_to_wake_up(struct task_struct *p, unsigned int state, int wake_flags)
+int try_to_wake_up(struct task_struct *p, unsigned int state, int wake_flags)
{
unsigned long flags;
int cpu, success = 0;
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 095b0aa378df..4b70cf8f1ec3 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -6838,6 +6838,10 @@ select_task_rq_fair(struct task_struct *p, int prev_cpu, int wake_flags)
if (wake_flags & WF_TTWU) {
record_wakee(p);
+ if ((wake_flags & WF_CURRENT_CPU) &&
+ cpumask_test_cpu(cpu, p->cpus_ptr))
+ return cpu;
+
if (sched_energy_enabled()) {
new_cpu = find_energy_efficient_cpu(p, prev_cpu);
if (new_cpu >= 0)
diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
index de53be905739..77f67d09b946 100644
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h
@@ -2052,13 +2052,14 @@ static inline int task_on_rq_migrating(struct task_struct *p)
}
/* Wake flags. The first three directly map to some SD flag value */
-#define WF_EXEC 0x02 /* Wakeup after exec; maps to SD_BALANCE_EXEC */
-#define WF_FORK 0x04 /* Wakeup after fork; maps to SD_BALANCE_FORK */
-#define WF_TTWU 0x08 /* Wakeup; maps to SD_BALANCE_WAKE */
+#define WF_EXEC 0x02 /* Wakeup after exec; maps to SD_BALANCE_EXEC */
+#define WF_FORK 0x04 /* Wakeup after fork; maps to SD_BALANCE_FORK */
+#define WF_TTWU 0x08 /* Wakeup; maps to SD_BALANCE_WAKE */
-#define WF_SYNC 0x10 /* Waker goes to sleep after wakeup */
-#define WF_MIGRATED 0x20 /* Internal use, task got migrated */
-#define WF_ON_CPU 0x40 /* Wakee is on_cpu */
+#define WF_SYNC 0x10 /* Waker goes to sleep after wakeup */
+#define WF_MIGRATED 0x20 /* Internal use, task got migrated */
+#define WF_ON_CPU 0x40 /* Wakee is on_cpu */
+#define WF_CURRENT_CPU 0x80 /* Prefer to move the wakee to the current CPU. */
#ifdef CONFIG_SMP
static_assert(WF_EXEC == SD_BALANCE_EXEC);
@@ -3112,6 +3113,8 @@ static inline bool is_per_cpu_kthread(struct task_struct *p)
extern void swake_up_all_locked(struct swait_queue_head *q);
extern void __prepare_to_swait(struct swait_queue_head *q, struct swait_queue *wait);
+extern int try_to_wake_up(struct task_struct *tsk, unsigned int state, int wake_flags);
+
#ifdef CONFIG_PREEMPT_DYNAMIC
extern int preempt_dynamic_mode;
extern int sched_dynamic_mode(const char *str);
--
2.34.1.703.g22d0c6ccf7-goog
next prev parent reply other threads:[~2022-01-13 23:40 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-01-13 23:39 [RFC PATCH v2 0/5] User Managed Concurrency Groups Peter Oskolkov
2022-01-13 23:39 ` Peter Oskolkov [this message]
2022-01-13 23:39 ` [RFC PATCH v2 2/5] x86/uaccess: Implement unsafe_try_cmpxchg_user() Peter Oskolkov
2022-01-13 23:39 ` [RFC PATCH v2 3/5] sched: User Mode Concurency Groups Peter Oskolkov
2022-01-13 23:39 ` [RFC PATCH v2 4/5] sched: UMCG: add a blocked worker list Peter Oskolkov
2022-01-17 9:19 ` Peter Zijlstra
2022-01-18 17:16 ` Peter Oskolkov
2022-01-27 15:37 ` Peter Zijlstra
2022-01-27 17:20 ` Peter Oskolkov
2022-01-13 23:39 ` [RFC PATCH v2 5/5] sched: UMCG: allow to sys_umcg_kick UMCG servers Peter Oskolkov
2022-01-27 16:35 ` 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=20220113233940.3608440-2-posk@google.com \
--to=posk@google.com \
--cc=avagin@google.com \
--cc=bristot@redhat.com \
--cc=bsegall@google.com \
--cc=dietmar.eggemann@arm.com \
--cc=jannh@google.com \
--cc=juri.lelli@redhat.com \
--cc=linux-api@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=mgorman@suse.de \
--cc=mingo@redhat.com \
--cc=peterz@infradead.org \
--cc=pjt@google.com \
--cc=posk@posk.io \
--cc=rostedt@goodmis.org \
--cc=tdelisle@uwaterloo.ca \
--cc=tglx@linutronix.de \
--cc=vincent.guittot@linaro.org \
--cc=x86@kernel.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).