lkml.org 
[lkml]   [2004]   [Dec]   [20]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
SubjectRE: [PATCH][1/2] adjust dirty threshold for lowmem-only mappings
Date
From


> On Mon, 20 Dec 2004, Rik van Riel wrote:
>
>> Simply running "dd if=/dev/zero of=/dev/hd<one you can miss>"
>> will result in OOM kills, with the dirty pagecache
>> completely filling up lowmem. This patch is part 1 to
>> fixing that problem.
>
> What I forgot to say is that in order to trigger this OOM
> Kill the dirty_limit of 40% needs to be more memory than
> what fits in low memory. So this will work on x86 with
> 4GB RAM, since the dirty_limit is 1.6GB, but the block
> device cache cannot grow that big because it is restricted
> to low memory.
>
> This has the effect of all low memory being tied up in
> Dirty page cache and userspace try_to_free_pages() skipping
> the writeout of these pages because the block device is
> congested.

I am just confirming that this is a real problem. The problem
more frequently shows up with block sizes above 4k on the
dd and also showed up on some platforms with just a mke2fs
on a slower device such as a USB hard drive.

Rik's patch has solved the issue and has been running under
stress (via ctcs) over the weekend without failure.

Regards,
Robert

-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/

\
 
 \ /
  Last update: 2005-03-22 14:08    [W:0.041 / U:0.412 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site