All of lore.kernel.org
 help / color / mirror / Atom feed
From: Nick Piggin <nickpiggin@yahoo.com.au>
To: Gregory Haskins <ghaskins@novell.com>
Cc: mingo@elte.hu, srostedt@redhat.com, peterz@infradead.org,
	linux-kernel@vger.kernel.org, linux-rt-users@vger.kernel.org,
	npiggin@suse.de, gregory.haskins@gmail.com
Subject: Re: [PATCH 2/5] sched: pull only one task during NEWIDLE balancing to limit critical section
Date: Tue, 26 Aug 2008 16:21:33 +1000	[thread overview]
Message-ID: <200808261621.33810.nickpiggin@yahoo.com.au> (raw)
In-Reply-To: <20080825201529.23217.8708.stgit@dev.haskins.net>

On Tuesday 26 August 2008 06:15, Gregory Haskins wrote:
> git-id c4acb2c0669c5c5c9b28e9d02a34b5c67edf7092 attempted to limit
> newidle critical section length by stopping after at least one task
> was moved.  Further investigation has shown that there are other
> paths nested further inside the algorithm which still remain that allow
> long latencies to occur with newidle balancing.  This patch applies
> the same technique inside balance_tasks() to limit the duration of
> this optional balancing operation.
>
> Signed-off-by: Gregory Haskins <ghaskins@novell.com>
> CC: Nick Piggin <npiggin@suse.de>

Hmm, this (andc4acb2c0669c5c5c9b28e9d02a34b5c67edf7092) still could
increase the amount of work to do significantly for workloads where
the CPU is going idle and pulling tasks over frequently. I don't
really like either of them too much.

Maybe increasing the limit would effectively amortize most of the
problem (say, limit to move 16 tasks at most).

  reply	other threads:[~2008-08-26  6:21 UTC|newest]

Thread overview: 54+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2008-08-25 20:15 [PATCH 0/5] sched: misc rt fixes for tip/sched/devel Gregory Haskins
2008-08-25 20:15 ` [PATCH 1/5] sched: only try to push a task on wakeup if it is migratable Gregory Haskins
2008-08-25 20:15 ` [PATCH 2/5] sched: pull only one task during NEWIDLE balancing to limit critical section Gregory Haskins
2008-08-26  6:21   ` Nick Piggin [this message]
2008-08-26 11:36     ` Gregory Haskins
2008-08-27  6:41       ` Nick Piggin
2008-08-27 11:50         ` Gregory Haskins
2008-08-27 11:57           ` Nick Piggin
2008-08-25 20:15 ` [PATCH 3/5] sched: make double-lock-balance fair Gregory Haskins
2008-08-25 20:15   ` Gregory Haskins
2008-08-26  6:14   ` Nick Piggin
2008-08-26 12:23     ` Gregory Haskins
2008-08-27  6:36       ` Nick Piggin
2008-08-27 11:41         ` Gregory Haskins
2008-08-27 11:53           ` Nick Piggin
2008-08-27 12:10             ` Gregory Haskins
2008-08-25 20:15 ` [PATCH 4/5] sched: add sched_class->needs_post_schedule() member Gregory Haskins
2008-08-25 20:15 ` [PATCH 5/5] sched: create "pushable_tasks" list to limit pushing to one attempt Gregory Haskins
2008-08-26 17:34 ` [PATCH v2 0/6] Series short description Gregory Haskins
2008-08-26 17:34   ` [PATCH v2 1/6] sched: only try to push a task on wakeup if it is migratable Gregory Haskins
2008-08-26 17:34   ` [PATCH v2 2/6] sched: pull only one task during NEWIDLE balancing to limit critical section Gregory Haskins
2008-08-26 17:34     ` Gregory Haskins
2008-08-26 17:35   ` [PATCH v2 3/6] sched: make double-lock-balance fair Gregory Haskins
2008-08-27  8:21     ` Peter Zijlstra
2008-08-27  8:25       ` Peter Zijlstra
2008-08-27 10:26       ` Nick Piggin
2008-08-27 10:41         ` Peter Zijlstra
2008-08-27 10:56           ` Nick Piggin
2008-08-27 10:57             ` Nick Piggin
2008-08-27 12:03               ` Gregory Haskins
2008-08-27 11:07             ` Peter Zijlstra
2008-08-27 11:17               ` Russell King
2008-08-27 12:00               ` Gregory Haskins
2008-08-29 12:49               ` Ralf Baechle
2008-08-27 12:13             ` Gregory Haskins
2008-08-27 12:02       ` Gregory Haskins
2008-08-26 17:35   ` [PATCH v2 4/6] sched: add sched_class->needs_post_schedule() member Gregory Haskins
2008-08-26 17:35   ` [PATCH v2 5/6] plist: fix PLIST_NODE_INIT to work with debug enabled Gregory Haskins
2008-08-26 17:35   ` [PATCH v2 6/6] sched: create "pushable_tasks" list to limit pushing to one attempt Gregory Haskins
2008-08-29 13:24     ` Gregory Haskins
2008-08-26 18:16   ` [PATCH v2 0/6] sched: misc rt fixes for tip/sched/devel (was: Series short description) Gregory Haskins
2008-08-27  8:33   ` [PATCH v2 0/6] Series short description Peter Zijlstra
2008-09-04 12:54 ` [TIP/SCHED/DEVEL PATCH v3 0/6] sched: misc rt fixes Gregory Haskins
2008-09-04 12:55   ` [TIP/SCHED/DEVEL PATCH v3 1/6] sched: only try to push a task on wakeup if it is migratable Gregory Haskins
2008-09-04 12:55   ` [TIP/SCHED/DEVEL PATCH v3 2/6] sched: pull only one task during NEWIDLE balancing to limit critical section Gregory Haskins
2008-09-04 12:55     ` Gregory Haskins
2008-09-04 12:55   ` [TIP/SCHED/DEVEL PATCH v3 3/6] sched: make double-lock-balance fair Gregory Haskins
2008-09-04 12:55   ` [TIP/SCHED/DEVEL PATCH v3 4/6] sched: add sched_class->needs_post_schedule() member Gregory Haskins
2008-09-04 20:36     ` Steven Rostedt
2008-09-04 20:36       ` Gregory Haskins
2008-09-04 12:55   ` [TIP/SCHED/DEVEL PATCH v3 5/6] plist: fix PLIST_NODE_INIT to work with debug enabled Gregory Haskins
2008-09-04 12:55   ` [TIP/SCHED/DEVEL PATCH v3 6/6] sched: create "pushable_tasks" list to limit pushing to one attempt Gregory Haskins
2008-09-04 21:16     ` Steven Rostedt
2008-09-04 21:26       ` Gregory Haskins

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=200808261621.33810.nickpiggin@yahoo.com.au \
    --to=nickpiggin@yahoo.com.au \
    --cc=ghaskins@novell.com \
    --cc=gregory.haskins@gmail.com \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-rt-users@vger.kernel.org \
    --cc=mingo@elte.hu \
    --cc=npiggin@suse.de \
    --cc=peterz@infradead.org \
    --cc=srostedt@redhat.com \
    /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 an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.