From: Ingo Molnar <mingo@elte.hu>
To: Michael Buesch <mbuesch@freenet.de>
Cc: linux-kernel@vger.kernel.org, ck@vds.kolivas.org, kernel@kolivas.org
Subject: Re: [PATCH, RFC] protect call to set_tsk_need_resched() by the rq-lock
Date: Wed, 8 Dec 2004 09:26:33 +0100 [thread overview]
Message-ID: <20041208082633.GA7720@elte.hu> (raw)
In-Reply-To: <200412080031.08490.mbuesch@freenet.de>
* Michael Buesch <mbuesch@freenet.de> wrote:
> > > The two attached patches (one against vanilla kernel and one
> > > against ck patchset) moves the rq-lock a few lines up in
> > > scheduler_tick() to also protect set_tsk_need_resched().
> > >
> > > Is that neccessary?
> >
> > scheduler_tick() is a special case, 'current' is pinned and cannot
> > go away, nor can it get off the runqueue.
>
> Can you explain in short, why this is the case, please? I don't really
> get behind it. How are the two things enforced?
'current' is the currently executing task and as such it wont get moved
off the runqueue. The only way to leave the runqueue is to execute
schedule() [or to be preempted].
Ingo
next prev parent reply other threads:[~2004-12-08 8:27 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2004-12-06 22:39 [PATCH, RFC] protect call to set_tsk_need_resched() by the rq-lock Michael Buesch
2004-12-07 13:10 ` Ingo Molnar
2004-12-07 23:30 ` Michael Buesch
2004-12-08 8:26 ` Ingo Molnar [this message]
2004-12-08 9:49 ` Michael Buesch
2004-12-08 10:29 ` Michael Buesch
2004-12-08 11:15 ` Ingo Molnar
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=20041208082633.GA7720@elte.hu \
--to=mingo@elte.hu \
--cc=ck@vds.kolivas.org \
--cc=kernel@kolivas.org \
--cc=linux-kernel@vger.kernel.org \
--cc=mbuesch@freenet.de \
/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