Re: Loopback filesystem still hangs on 2.4.0-test13-pre7

From: Joel Koerwer (joel@ideacode.com)
Date: Fri Jan 05 2001 - 23:28:45 EST


I can't get it to fail either. All I had to do previously to get it to
fail was write a large amount of data to the loopback mounted
filesystem (rpm, cp, dd, anything), but now nothing...wonderful.
Thanks Jens. I didn't get any errors, cosmetic or otherwise (of
course, I'm still avoiding devfs, so I wouldn't expect to see the same errors
as Bill....).

I would also say that a fix definetely exists in this case!

Thanks again.

William Stearns schrieb auf Jan 5, 2001 Über "Re: Loopback filesystem still...":

   |> Date: Fri, 5 Jan 2001 13:38:39 -0500 (EST)
   |> From: William Stearns <wstearns@pobox.com>
   |> To: Jens Axboe <axboe@suse.de>, Joel Koerwer <joel@ideacode.com>
   |> Cc: ML-linux-kernel <linux-kernel@vger.kernel.org>,
   |> "Ts'o, Theodore -- Theodore Ts'o" <tytso@mit.edu>, tytso@valinux.com,
   |> Jeff Garzik <jgarzik@mandrakesoft.com>
   |> Subject: Re: Loopback filesystem still hangs on 2.4.0-test13-pre7
   |>
   |> Good day, all,
   |>
   |> On Thu, 4 Jan 2001, Jens Axboe wrote:
   |>
   |> > On Wed, Jan 03 2001, William Stearns wrote:
   |> > > This is just meant as an informational message, not a complaint.
   |> > > Ted, could you note that this still exists on 2.4.0-test13-pre7 in the
   |> > > todo page? Many thanks.
   |> > >
   |> > > [1.] One line summary of the problem:
   |> > > Loopback filesystem writes still hang on 2.4.0-test13-pre7.
   |> >
   |> > Could you try with this patch:
   |> >
   |> > *.kernel.org/pub/linux/kernel/people/axboe/patches/2.4-prerelease/loop-remap-2
   |> >
   |> > it survives 10 runs of your script and dbench abuse etc. If there are still
   |> > problems, I'd like to know... Should be faster too :-)
   |>
   |> I applied your Jan 4th version of this patch to 2.4.0-prerelease
   |> proper (Linus' Jan 4th diff had changes to fs/buffer.c that conflicted).
   |> I didn't apply either of the other patches in that directory.
   |> When I booted it, I got:
   |>
   |> ...
   |> devfs: devfs_register(): device already registered: "252"
   |> devfs: devfs_register(): device already registered: "253"
   |> devfs: devfs_register(): device already registered: "254"
   |> loop: loaded (max 255 devices)
   |>
   |> , but I suspect this is cosmetic.
   |> The verdict? This patch is marvelous! I _cannot_ crash it, even
   |> under heavy load. My test script went through 256 passes without even a
   |> glitch - previous kernels would have left one or more tasks in the "D"
   |> state by pass 16 or earlier without fail. Lots of bash's filling up
   |> memory and mostly filling swap, no problem (in fact, I had to kill off a
   |> few when I ran out of file descriptors at 1500 processes). Running X and
   |> some X apps (including xmms, which always seemed to spell death to old
   |> kernels) was also no problem.
   |> In short, _I_ _can't_ _get_ _it_ _to_ _fail_! I'm tremendously
   |> happy with the patch.
   |> I also agree with the speed assessment - 70M of linux source code
   |> copies (granted, between caches) in only a few seconds once the cache is
   |> loaded.
   |>
   |> I realize that my 24 hours of testing hardly counts as validation
   |> of the patch - could others beat on it as well (Joel?)? Jens, any chance
   |> you could update it for 2.4.0-final?
   |> My solitary vote is for moving this to "Fix exists but isn't
   |> merged" on Ted's list.
   |> Once again, my sincere thanks to both Jens and Jeff for their work
   |> on the loop filesystem. I'll keep beating on it.
   |> Cheers,
   |> - Bill
   |>
   |> ---------------------------------------------------------------------------
   |> "Scattered showers my ass!"
   |> -- Noah
   |> (Courtesy of "Michael B. Trausch" <mtrausch@wcnet.org>)
   |> --------------------------------------------------------------------------
   |> William Stearns (wstearns@pobox.com). Mason, Buildkernel, named2hosts,
   |> and ipfwadm2ipchains are at: http://www.pobox.com/~wstearns
   |> LinuxMonth; articles for Linux Enthusiasts! http://www.linuxmonth.com
   |> --------------------------------------------------------------------------
   |>

-- 
Joel Koerwer, Technology Specialist
ideacode.com, Inc.          http://www.ideacode.com/
US +1 919 247 4798
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