From: Peter Oskolkov <posk@google.com>
To: Peter Zijlstra <peterz@infradead.org>,
Ingo Molnar <mingo@redhat.com>,
Thomas Gleixner <tglx@linutronix.de>,
linux-kernel@vger.kernel.org, linux-api@vger.kernel.org
Cc: Paul Turner <pjt@google.com>, Ben Segall <bsegall@google.com>,
Peter Oskolkov <posk@google.com>, Peter Oskolkov <posk@posk.io>,
Joel Fernandes <joel@joelfernandes.org>,
Andrew Morton <akpm@linux-foundation.org>,
Andrei Vagin <avagin@google.com>,
Jim Newsome <jnewsome@torproject.org>
Subject: [RFC PATCH v0.1 3/9] sched: add WF_CURRENT_CPU and externise ttwu
Date: Thu, 20 May 2021 11:36:08 -0700 [thread overview]
Message-ID: <20210520183614.1227046-4-posk@google.com> (raw)
In-Reply-To: <20210520183614.1227046-1-posk@google.com>
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>
---
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 3d2527239c3e..88506bc2617f 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -3683,8 +3683,7 @@ static void ttwu_queue(struct task_struct *p, int cpu, int wake_flags)
* 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 161b92aa1c79..e55256bbb60b 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -6764,6 +6764,10 @@ 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 8f0194cee0ba..205d05571d9e 100644
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h
@@ -2027,13 +2027,14 @@ 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);
@@ -3018,6 +3019,8 @@ 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);
--
2.31.1.818.g46aad6cb9e-goog
next prev parent reply other threads:[~2021-05-20 18:36 UTC|newest]
Thread overview: 35+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-05-20 18:36 [RFC PATCH v0.1 0/9] UMCG early preview/RFC patchset Peter Oskolkov
2021-05-20 18:36 ` [RFC PATCH v0.1 1/9] sched/umcg: add UMCG syscall stubs and CONFIG_UMCG Peter Oskolkov
2021-05-20 18:36 ` [RFC PATCH v0.1 2/9] sched/umcg: add uapi/linux/umcg.h and sched/umcg.c Peter Oskolkov
2021-05-20 18:36 ` Peter Oskolkov [this message]
2021-05-20 18:36 ` [RFC PATCH v0.1 4/9] sched/umcg: implement core UMCG API Peter Oskolkov
2021-05-21 19:06 ` Andrei Vagin
2021-05-21 21:31 ` Jann Horn
2021-05-21 22:03 ` Peter Oskolkov
2021-05-21 19:32 ` Andy Lutomirski
2021-05-21 22:01 ` Peter Oskolkov
2021-05-21 21:33 ` Jann Horn
2021-06-09 13:01 ` Peter Zijlstra
2021-05-20 18:36 ` [RFC PATCH v0.1 5/9] lib/umcg: implement UMCG core API for userspace Peter Oskolkov
2021-05-20 18:36 ` [RFC PATCH v0.1 6/9] selftests/umcg: add UMCG core API selftest Peter Oskolkov
2021-05-20 18:36 ` [RFC PATCH v0.1 7/9] sched/umcg: add UMCG server/worker API (early RFC) Peter Oskolkov
2021-05-21 20:17 ` Andrei Vagin
2021-05-20 18:36 ` [RFC PATCH v0.1 8/9] lib/umcg: " Peter Oskolkov
2021-05-20 18:36 ` [RFC PATCH v0.1 9/9] selftests/umcg: add UMCG server/worker API selftest Peter Oskolkov
2021-05-20 21:17 ` [RFC PATCH v0.1 0/9] UMCG early preview/RFC patchset Jonathan Corbet
2021-05-20 21:38 ` Peter Oskolkov
2021-05-21 0:15 ` Randy Dunlap
2021-05-21 8:04 ` Peter Zijlstra
2021-05-21 15:08 ` Jonathan Corbet
2021-05-21 16:03 ` Peter Oskolkov
2021-05-21 19:17 ` Jonathan Corbet
2021-05-27 0:06 ` Peter Oskolkov
2021-05-27 15:41 ` Jonathan Corbet
[not found] ` <CAEWA0a72SvpcuN4ov=98T3uWtExPCr7BQePOgjkqD1ofWKEASw@mail.gmail.com>
2021-05-21 19:13 ` Peter Oskolkov
2021-05-21 23:08 ` Jann Horn
2021-06-09 12:54 ` Peter Zijlstra
2021-06-09 20:18 ` Peter Oskolkov
2021-06-10 18:02 ` Peter Zijlstra
2021-06-10 20:06 ` Peter Oskolkov
2021-07-07 17:45 ` Thierry Delisle
2021-07-08 21:44 ` Peter Oskolkov
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