From: Andrew Morton <akpm@linux-foundation.org>
To: "J.J. Green" <j.j.green@sheffield.ac.uk>
Cc: linux-kernel@vger.kernel.org, sparclinux@vger.kernel.org
Subject: Re: sparc64 / bbc_i2c.c
Date: Sun, 25 Feb 2007 04:47:54 -0800 [thread overview]
Message-ID: <20070225044754.1d849a8d.akpm@linux-foundation.org> (raw)
In-Reply-To: <1171978032.18442.11.camel@lax.shef.ac.uk>
> On Tue, 20 Feb 2007 13:27:12 +0000 "J.J. Green" <j.j.green@sheffield.ac.uk> wrote:
> Hi all
>
> I got bitten by this problem on sparc64 (a blade 1000)
>
> http://ubuntuforums.org/showthread.php?t=297474
>
> summary :
>
> modprobe bbc
>
> runs kenvctrld which uses 100% of a CPU for 5 seconds,
> then 0% for 5 seconds, then 100% .. and so on. The author
> cited above suggests removing the line
>
> remove_wait_queue(&bp->wq, &wait);
>
> in the function
>
> static int wait_for_pin(struct bbc_i2c_bus *bp, u8 *status)
>
> Is there a better way?
>
> I can test patches if that would be helpful.
>
The code around there looks relatively unbuggy to me. Removing that
remove_wait_queue() would be very bad - it would cause later stack
corruption.
msleep_interruptible() certainly shouldn't consume CPU like that. Do we
know where the CPU time is being spent? The output of:
readprofile -r
sleep 10
readprofile -n -v -m /boot/System.map | sort -n -k 3 | tail -40
would tell us.
next prev parent reply other threads:[~2007-02-25 12:48 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-02-20 13:27 J.J. Green
2007-02-25 12:47 ` Andrew Morton [this message]
2007-02-25 13:33 ` Emanuele Rocca
2007-02-25 23:58 ` J.J.Green
2007-02-26 18:12 ` David Miller
2007-02-27 5:22 ` Joerg Friedrich
2007-02-27 5:29 ` David Miller
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=20070225044754.1d849a8d.akpm@linux-foundation.org \
--to=akpm@linux-foundation.org \
--cc=j.j.green@sheffield.ac.uk \
--cc=linux-kernel@vger.kernel.org \
--cc=sparclinux@vger.kernel.org \
/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
Powered by JetHome