Re: 2.6.24-rc3-mm1 (sync is slow ?)

Andrew Morton
2007-11-21T08:49:23Z

On Wed, 21 Nov 2007 17:42:15 +0900 KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> wrote:

> Hi, Andrew
>
> I got following result in 'sync' command.
> It was too slow. (memory controller config is off ;)
> I attaches my .config.
> ==
> [2.6.24-rc3-mm1]
> [kamezawa@dr-test2 ~]$ dd if=/dev/zero of=./tmpfile bs=4096 count=100000
> 100000+0 records in
> 100000+0 records out
> 409600000 bytes (410 MB) copied, 1.46706 seconds, 279 MB/s
> [kamezawa@dr-test2 ~]$ time sync
>
> real 3m6.440s
> user 0m0.000s
> sys 0m0.133s
>
>
> on, 2.6.23-rc2-mm1, 2.6.23-rc3 there was no problem.
> ==
> [2.6.24-rc3]
> [kamezawa@dr-test2 ~]$ dd if=/dev/zero of=tmpfile bs=4096 count=100000
> 100000+0 records in
> 100000+0 records out
> 409600000 bytes (410 MB) copied, 2.07717 seconds, 197 MB/s
> [kamezawa@dr-test2 ~]$ time sync
>
> real 0m9.935s
> user 0m0.001s
> sys 0m0.113s
>
> [2.6.24-rc3]
> [kamezawa@dr-test2 ~]$ dd if=/dev/zero of=./tmpfile bs=4096 count=100000
> 100000+0 records in
> 100000+0 records out
> 409600000 bytes (410 MB) copied, 1.37147 seconds, 299 MB/s
> [kamezawa@dr-test2 ~]$ time sync[2.6.24-rc2-mm1]
>
>
> real 0m11.718s
> user 0m0.000s
> sys 0m0.138s

Well I wonder how we did that.

It seems OK here from a quick test (i386, ext3-on-IDE).

Maybe device driver/block breakage?