* [PATCH] sched: shorten setting the allowed cpu mask of task
@ 2011-05-06 12:52 Hillf Danton
2011-05-09 4:39 ` Yong Zhang
0 siblings, 1 reply; 6+ messages in thread
From: Hillf Danton @ 2011-05-06 12:52 UTC (permalink / raw)
To: LKML; +Cc: Ingo Molnar, Peter Zijlstra, Mike Galbraith, Yong Zhang
When setting the allowed cpu mask for a given task, if the task is
already bound to certain cpu, after checking the validity of the new
mask of allowed cpus, job is done, and no further efforts needed for
the valid case as well.
Signed-off-by: Hillf Danton <dhillf@gmail.com>
---
--- a/kernel/sched.c 2011-04-27 11:48:50.000000000 +0800
+++ b/kernel/sched.c 2011-05-06 20:39:58.000000000 +0800
@@ -5899,9 +5899,9 @@ again:
goto out;
}
- if (unlikely((p->flags & PF_THREAD_BOUND) && p != current &&
- !cpumask_equal(&p->cpus_allowed, new_mask))) {
- ret = -EINVAL;
+ if ((p->flags & PF_THREAD_BOUND) && p != current) {
+ if (!cpumask_equal(&p->cpus_allowed, new_mask))
+ ret = -EINVAL;
goto out;
}
^ permalink raw reply [flat|nested] 6+ messages in thread* Re: [PATCH] sched: shorten setting the allowed cpu mask of task 2011-05-06 12:52 [PATCH] sched: shorten setting the allowed cpu mask of task Hillf Danton @ 2011-05-09 4:39 ` Yong Zhang 2011-05-09 12:52 ` Hillf Danton 0 siblings, 1 reply; 6+ messages in thread From: Yong Zhang @ 2011-05-09 4:39 UTC (permalink / raw) To: Hillf Danton; +Cc: LKML, Ingo Molnar, Peter Zijlstra, Mike Galbraith On Fri, May 6, 2011 at 8:52 PM, Hillf Danton <dhillf@gmail.com> wrote: > When setting the allowed cpu mask for a given task, if the task is > already bound to certain cpu, after checking the validity of the new Maybe we don't need to restrict it only on task bound to certain cpu. > mask of allowed cpus, job is done, and no further efforts needed for > the valid case as well. > > Signed-off-by: Hillf Danton <dhillf@gmail.com> > --- > > --- a/kernel/sched.c 2011-04-27 11:48:50.000000000 +0800 > +++ b/kernel/sched.c 2011-05-06 20:39:58.000000000 +0800 > @@ -5899,9 +5899,9 @@ again: > goto out; > } > > - if (unlikely((p->flags & PF_THREAD_BOUND) && p != current && > - !cpumask_equal(&p->cpus_allowed, new_mask))) { > - ret = -EINVAL; > + if ((p->flags & PF_THREAD_BOUND) && p != current) { > + if (!cpumask_equal(&p->cpus_allowed, new_mask)) IOW, we could make '!cpumask_equal(&p->cpus_allowed, new_mask)' be a separated condition. And I don't see any potential problem with it. Thanks, Yong > + ret = -EINVAL; > goto out; > } > -- Only stand for myself ^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH] sched: shorten setting the allowed cpu mask of task 2011-05-09 4:39 ` Yong Zhang @ 2011-05-09 12:52 ` Hillf Danton 2011-05-09 14:07 ` Yong Zhang 0 siblings, 1 reply; 6+ messages in thread From: Hillf Danton @ 2011-05-09 12:52 UTC (permalink / raw) To: Yong Zhang; +Cc: LKML, Ingo Molnar, Peter Zijlstra, Mike Galbraith On Mon, May 9, 2011 at 12:39 PM, Yong Zhang <yong.zhang0@gmail.com> wrote: > On Fri, May 6, 2011 at 8:52 PM, Hillf Danton <dhillf@gmail.com> wrote: >> When setting the allowed cpu mask for a given task, if the task is >> already bound to certain cpu, after checking the validity of the new > > Maybe we don't need to restrict it only on task bound to certain cpu. > Hi Yong The original code guards, I guess, casual change in the mask of allowed CPUs, if bounded, for tasks such as the workers of work queue. So the restriction looks necessary. thanks Hillf ^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH] sched: shorten setting the allowed cpu mask of task 2011-05-09 12:52 ` Hillf Danton @ 2011-05-09 14:07 ` Yong Zhang 2011-05-10 12:38 ` Hillf Danton 2011-05-16 10:37 ` [tip:sched/core] sched: Avoid going ahead if ->cpus_allowed is not changed tip-bot for Yong Zhang 0 siblings, 2 replies; 6+ messages in thread From: Yong Zhang @ 2011-05-09 14:07 UTC (permalink / raw) To: Hillf Danton; +Cc: LKML, Ingo Molnar, Peter Zijlstra, Mike Galbraith On Mon, May 09, 2011 at 08:52:53PM +0800, Hillf Danton wrote: > On Mon, May 9, 2011 at 12:39 PM, Yong Zhang <yong.zhang0@gmail.com> wrote: > > On Fri, May 6, 2011 at 8:52 PM, Hillf Danton <dhillf@gmail.com> wrote: > >> When setting the allowed cpu mask for a given task, if the task is > >> already bound to certain cpu, after checking the validity of the new > > > > Maybe we don't need to restrict it only on task bound to certain cpu. > > > Hi Yong > > The original code guards, I guess, casual change in the mask of > allowed CPUs, if bounded, > for tasks such as the workers of work queue. So the restriction looks necessary. Yeah, that is true; but I don't think we need to go ahead for unbounded task if cpu_allowed will not be changed. My thought is like below: --- Subject: [PATCH] sched: avoid going ahead if cpu_allowed will not be changed If cpumask_equal(&p->cpus_allowed, new_mask) is true, seems there is no reason to prevent set_cpus_allowed_ptr() return directly. Signed-off-by: Yong Zhang <yong.zhang0@gmail.com> --- kernel/sched.c | 6 ++++-- 1 files changed, 4 insertions(+), 2 deletions(-) diff --git a/kernel/sched.c b/kernel/sched.c index da93381..56bc1fa 100644 --- a/kernel/sched.c +++ b/kernel/sched.c @@ -5946,13 +5946,15 @@ int set_cpus_allowed_ptr(struct task_struct *p, const struct cpumask *new_mask) rq = task_rq_lock(p, &flags); + if (cpumask_equal(&p->cpus_allowed, new_mask)) + goto out; + if (!cpumask_intersects(new_mask, cpu_active_mask)) { ret = -EINVAL; goto out; } - if (unlikely((p->flags & PF_THREAD_BOUND) && p != current && - !cpumask_equal(&p->cpus_allowed, new_mask))) { + if (unlikely((p->flags & PF_THREAD_BOUND) && p != current)) { ret = -EINVAL; goto out; } -- 1.7.1 ^ permalink raw reply related [flat|nested] 6+ messages in thread
* Re: [PATCH] sched: shorten setting the allowed cpu mask of task 2011-05-09 14:07 ` Yong Zhang @ 2011-05-10 12:38 ` Hillf Danton 2011-05-16 10:37 ` [tip:sched/core] sched: Avoid going ahead if ->cpus_allowed is not changed tip-bot for Yong Zhang 1 sibling, 0 replies; 6+ messages in thread From: Hillf Danton @ 2011-05-10 12:38 UTC (permalink / raw) To: Yong Zhang; +Cc: LKML, Ingo Molnar, Peter Zijlstra, Mike Galbraith On Mon, May 9, 2011 at 10:07 PM, Yong Zhang <yong.zhang0@gmail.com> wrote: > On Mon, May 09, 2011 at 08:52:53PM +0800, Hillf Danton wrote: >> On Mon, May 9, 2011 at 12:39 PM, Yong Zhang <yong.zhang0@gmail.com> wrote: >> > On Fri, May 6, 2011 at 8:52 PM, Hillf Danton <dhillf@gmail.com> wrote: >> >> When setting the allowed cpu mask for a given task, if the task is >> >> already bound to certain cpu, after checking the validity of the new >> > >> > Maybe we don't need to restrict it only on task bound to certain cpu. >> > >> Hi Yong >> >> The original code guards, I guess, casual change in the mask of >> allowed CPUs, if bounded, >> for tasks such as the workers of work queue. So the restriction looks necessary. > > Yeah, that is true; but I don't think we need to go ahead for > unbounded task if cpu_allowed will not be changed. > > My thought is like below: > > --- > Subject: [PATCH] sched: avoid going ahead if cpu_allowed will not be changed > > If cpumask_equal(&p->cpus_allowed, new_mask) is true, seems > there is no reason to prevent set_cpus_allowed_ptr() return > directly. > > Signed-off-by: Yong Zhang <yong.zhang0@gmail.com> Acked-by: Hillf Danton <dhillf@gmail.com> > --- > kernel/sched.c | 6 ++++-- > 1 files changed, 4 insertions(+), 2 deletions(-) > > diff --git a/kernel/sched.c b/kernel/sched.c > index da93381..56bc1fa 100644 > --- a/kernel/sched.c > +++ b/kernel/sched.c > @@ -5946,13 +5946,15 @@ int set_cpus_allowed_ptr(struct task_struct *p, const struct cpumask *new_mask) > > rq = task_rq_lock(p, &flags); > > + if (cpumask_equal(&p->cpus_allowed, new_mask)) > + goto out; > + > if (!cpumask_intersects(new_mask, cpu_active_mask)) { > ret = -EINVAL; > goto out; > } > > - if (unlikely((p->flags & PF_THREAD_BOUND) && p != current && > - !cpumask_equal(&p->cpus_allowed, new_mask))) { > + if (unlikely((p->flags & PF_THREAD_BOUND) && p != current)) { > ret = -EINVAL; > goto out; > } > -- > 1.7.1 > > ^ permalink raw reply [flat|nested] 6+ messages in thread
* [tip:sched/core] sched: Avoid going ahead if ->cpus_allowed is not changed 2011-05-09 14:07 ` Yong Zhang 2011-05-10 12:38 ` Hillf Danton @ 2011-05-16 10:37 ` tip-bot for Yong Zhang 1 sibling, 0 replies; 6+ messages in thread From: tip-bot for Yong Zhang @ 2011-05-16 10:37 UTC (permalink / raw) To: linux-tip-commits Cc: linux-kernel, hpa, mingo, dhillf, a.p.zijlstra, yong.zhang0, tglx, mingo Commit-ID: db44fc017d5989302713ab4e7f9e922b648f4b59 Gitweb: http://git.kernel.org/tip/db44fc017d5989302713ab4e7f9e922b648f4b59 Author: Yong Zhang <yong.zhang0@gmail.com> AuthorDate: Mon, 9 May 2011 22:07:05 +0800 Committer: Ingo Molnar <mingo@elte.hu> CommitDate: Mon, 16 May 2011 11:01:18 +0200 sched: Avoid going ahead if ->cpus_allowed is not changed If cpumask_equal(&p->cpus_allowed, new_mask) is true, seems there is no reason to prevent set_cpus_allowed_ptr() return directly. Signed-off-by: Yong Zhang <yong.zhang0@gmail.com> Acked-by: Hillf Danton <dhillf@gmail.com> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Link: http://lkml.kernel.org/r/20110509140705.GA2219@zhy Signed-off-by: Ingo Molnar <mingo@elte.hu> --- kernel/sched.c | 6 ++++-- 1 files changed, 4 insertions(+), 2 deletions(-) diff --git a/kernel/sched.c b/kernel/sched.c index b8b9a7d..70bec4f 100644 --- a/kernel/sched.c +++ b/kernel/sched.c @@ -5946,13 +5946,15 @@ int set_cpus_allowed_ptr(struct task_struct *p, const struct cpumask *new_mask) rq = task_rq_lock(p, &flags); + if (cpumask_equal(&p->cpus_allowed, new_mask)) + goto out; + if (!cpumask_intersects(new_mask, cpu_active_mask)) { ret = -EINVAL; goto out; } - if (unlikely((p->flags & PF_THREAD_BOUND) && p != current && - !cpumask_equal(&p->cpus_allowed, new_mask))) { + if (unlikely((p->flags & PF_THREAD_BOUND) && p != current)) { ret = -EINVAL; goto out; } ^ permalink raw reply related [flat|nested] 6+ messages in thread
end of thread, other threads:[~2011-05-16 10:38 UTC | newest] Thread overview: 6+ messages (download: mbox.gz follow: Atom feed -- links below jump to the message on this page -- 2011-05-06 12:52 [PATCH] sched: shorten setting the allowed cpu mask of task Hillf Danton 2011-05-09 4:39 ` Yong Zhang 2011-05-09 12:52 ` Hillf Danton 2011-05-09 14:07 ` Yong Zhang 2011-05-10 12:38 ` Hillf Danton 2011-05-16 10:37 ` [tip:sched/core] sched: Avoid going ahead if ->cpus_allowed is not changed tip-bot for Yong Zhang
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