From: "Dmitry Adamushko" <dmitry.adamushko@gmail.com>
To: "Steven Rostedt" <srostedt@redhat.com>
Cc: "Gregory Haskins" <ghaskins@novell.com>,
"Ingo Molnar" <mingo@elte.hu>, "Balbir Singh" <balbir@in.ibm.com>,
"Peter Zijlstra" <a.p.zijlstra@chello.nl>,
vatsa@linux.vnet.ibm.com,
"LKML Kernel" <linux-kernel@vger.kernel.org>
Subject: RT Load balance changes in sched-devel
Date: Sun, 9 Dec 2007 18:16:52 +0100 [thread overview]
Message-ID: <b647ffbd0712090916l4eb9a944r4726680a5fdcae46@mail.gmail.com> (raw)
In-Reply-To: <4756D709.1020901@redhat.com>
[ cc'ed lkml ]
I guess, one possible load-balancing point is out of consideration --
sched_setscheduler()
(also rt_mutex_setprio()).
(1) NORMAL --> RT, when p->se.on_rq == 1 && ! task_running(rq, p)
(2) RT --> NORMAL, when task_running(rq, p) == 1
e.g. for (2) we may even get a completely idle rq (schedule() -->
schedule_balance_rt() will not help due to schedule_balance_rt()
having a rt_task(prev) check in place... and 'prev' is of NORMAL type
when it's scheduled out).
btw., both cases would be addressed by placing load-balance points
into sched_class_rt->{enqueue,dequeue}_task_rt()... push_rt_tasks()
and pull_rt_tasks() respectively. As a side effect (I think,
technically, it would be possible), 3 out of 4 *_balance_rt() calls
(the exception: schedule_tail_balance_rt()) in schedule() would become
unnecessary.
_BUT_
the enqueue/dequeue() interface would become less straightforward,
logically-wise.
Something like:
rq = activate_task(rq, ...) ; /* may unlock rq and lock/return another one */
would complicate the existing use cases.
--
Best regards,
Dmitry Adamushko
next parent reply other threads:[~2007-12-09 17:17 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20071130145939.GN5681@linux.vnet.ibm.com>
[not found] ` <b647ffbd0712011156p252ae29dnfa75494e4d2c845c@mail.gmail.com>
[not found] ` <20071203182223.GA4133@linux.vnet.ibm.com>
[not found] ` <47556B23.2060909@redhat.com>
[not found] ` <20071204153542.GC3388@linux.vnet.ibm.com>
[not found] ` <b647ffbd0712040828l51a26a82jc0f38d3f4aa2291e@mail.gmail.com>
[not found] ` <20071205134036.GA21933@linux.vnet.ibm.com>
[not found] ` <4756B8E9.3080709@redhat.com>
[not found] ` <20071205164800.GA24767@linux.vnet.ibm.com>
[not found] ` <4756D709.1020901@redhat.com>
2007-12-09 17:16 ` Dmitry Adamushko [this message]
2007-12-09 18:32 ` RT Load balance changes in sched-devel Gregory Haskins
2007-12-10 0:57 ` Steven Rostedt
2007-12-10 2:53 ` [PATCH RFC] sched: Fixed missed rt-balance points on priority shifts Gregory Haskins
2007-12-10 3:18 ` Gregory Haskins
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