From: Alan Cox <alan@lxorguk.ukuu.org.uk>
To: Mikulas Patocka <mpatocka@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>,
linux-kernel@vger.kernel.org, mingo@elte.hu, rml@tech9.net,
Alasdair G Kergon <agk@redhat.com>, Milan Broz <mbroz@redhat.com>
Subject: Re: Active waiting with yield()
Date: Mon, 17 Nov 2008 18:01:49 +0000 [thread overview]
Message-ID: <20081117180149.7a48d2e9@lxorguk.ukuu.org.uk> (raw)
In-Reply-To: <Pine.LNX.4.64.0811171228500.4019@hs20-bc2-1.build.redhat.com>
> --- so if the driver processes more than 100000 requests between reboots,
> wait queues actually slow things down.
Versus power consumption and virtualisation considerations. Plus your
numbers are wrong. You seem terribly keen to ignore the fact that the
true cost is a predicted branch and usually a predicted branch of a
cached variable and you'll only touch the wait queue in rare cases.
I'd also note as an aside modern drivers usually run off krefs so
destruction and thus closedown is refcounted and comes off the last kref
destruct.
Alan
next prev parent reply other threads:[~2008-11-17 18:02 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-11-14 18:59 Mikulas Patocka
2008-11-14 19:06 ` Alan Cox
2008-11-14 19:34 ` Mikulas Patocka
2008-11-14 20:57 ` Peter Zijlstra
2008-11-14 21:41 ` Mikulas Patocka
2008-11-15 22:55 ` Peter Zijlstra
2008-11-17 17:39 ` Mikulas Patocka
2008-11-17 18:01 ` Alan Cox [this message]
2008-11-18 14:34 ` Mikulas Patocka
2008-11-18 14:40 ` Alan Cox
2008-11-18 17:11 ` Mikulas Patocka
2008-11-18 21:26 ` Alan Cox
2008-11-20 9:18 ` Mikulas Patocka
2008-11-19 16:14 ` Peter Zijlstra
2008-11-18 14:49 ` Arjan van de Ven
2008-11-18 17:14 ` Mikulas Patocka
2008-11-14 21:21 ` Alan Cox
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=20081117180149.7a48d2e9@lxorguk.ukuu.org.uk \
--to=alan@lxorguk.ukuu.org.uk \
--cc=agk@redhat.com \
--cc=linux-kernel@vger.kernel.org \
--cc=mbroz@redhat.com \
--cc=mingo@elte.hu \
--cc=mpatocka@redhat.com \
--cc=peterz@infradead.org \
--cc=rml@tech9.net \
/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
all inboxes | Powered by JetHome®