lkml.org 
[lkml]   [2007]   [Nov]   [6]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: writeout stalls in current -git
On Tue, Nov 06, 2007 at 10:53:25PM +0100, Torsten Kaiser wrote:
> On 11/6/07, David Chinner <dgc@sgi.com> wrote:
> > Rather than vmstat, can you use something like iostat to show how busy your
> > disks are? i.e. are we seeing RMW cycles in the raid5 or some such issue.
>
> Both "vmstat 10" and "iostat -x 10" output from this test:
> procs -----------memory---------- ---swap-- -----io---- -system-- ----cpu----
> r b swpd free buff cache si so bi bo in cs us sy id wa
> 2 0 0 3700592 0 85424 0 0 31 83 108 244 2 1 95 1
> -> emerge reads something, don't knwo for sure what...
> 1 0 0 3665352 0 87940 0 0 239 2 343 585 2 1 97 0
....
>
> The last 20% of the btrace look more or less completely like this, no
> other programs do any IO...
>
> 253,0 3 104626 526.293450729 974 C WS 79344288 + 8 [0]
> 253,0 3 104627 526.293455078 974 C WS 79344296 + 8 [0]
> 253,0 1 36469 444.513863133 1068 Q WS 154998480 + 8 [xfssyncd]
> 253,0 1 36470 444.513863135 1068 Q WS 154998488 + 8 [xfssyncd]
^^
Apparently we are doing synchronous writes. That would explain why
it is slow. We shouldn't be doing synchronous writes here. I'll see if
I can reproduce this.

<goes off and looks>

Yes, I can reproduce the sync writes coming out of xfssyncd. I'll
look into this further and send a patch when I have something concrete.

Cheers,

Dave.
--
Dave Chinner
Principal Engineer
SGI Australian Software Group
-
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: 2007-11-07 00:35    [W:0.161 / U:0.772 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site