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

[Andrew Morton <akpm@linux-foundation.org>]

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?
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