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

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