From: Jens Axboe <axboe@suse.de>
To: "M. Edward Borasky" <znmeb@cesmail.net>
Cc: Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: Negative "ios_in_flight" in the 2.4 kernel
Date: Wed, 22 Dec 2004 12:16:43 +0100 [thread overview]
Message-ID: <20041222111642.GD12463@suse.de> (raw)
In-Reply-To: <1103691937.23157.14.camel@DreamGate>
On Tue, Dec 21 2004, M. Edward Borasky wrote:
> I've been looking at some "iostat" data from a 2.4.26 machine. The
> device utilizations are 100 percent, even when the disk is idle, which
> is mathematically impossible. By doing some digging, I discovered this
> is a kernel bug, caused by "hd->ios_in_flight" going negative. The
> relevant code appears to my untrained eyes to be in
> drivers/block/ll_rw_blk.c, specifically
>
>
> static inline void down_ios(struct hd_struct *hd)
> {
> disk_round_stats(hd);
> --hd->ios_in_flight;
> }
>
> static inline void up_ios(struct hd_struct *hd)
> {
> disk_round_stats(hd);
> ++hd->ios_in_flight;
> }
>
> Question: wouldn't a simple refusal to decrement ios_in_flight in
> "down_ios" if it's zero fix this, or am I missing something?
That would paper over the real bug, but it will work for you.
--
Jens Axboe
next prev parent reply other threads:[~2004-12-22 11:16 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2004-12-22 5:05 Negative "ios_in_flight" in the 2.4 kernel M. Edward Borasky
2004-12-22 11:16 ` Jens Axboe [this message]
2004-12-22 15:19 ` M. Edward Borasky
2004-12-22 15:58 ` Marcelo Tosatti
2004-12-23 8:08 ` Jens Axboe
2004-12-23 15:30 ` M. Edward Borasky
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=20041222111642.GD12463@suse.de \
--to=axboe@suse.de \
--cc=linux-kernel@vger.kernel.org \
--cc=znmeb@cesmail.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