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SubjectRe: 40% IDE performance regression going from FC3 to FC5 with same kernel
On 4/8/06, Arjan van de Ven <arjan@infradead.org> wrote:
>
> > Just for the record - no, even rebuilding same kernel with same GCC
> > (3.4.4) under FC5, disk performance is much slower than FC3 -
> > according to hdparm _and_ dd tests.
>
> what happens if you kill hald and other inotify using animals?

Thanks Arjan for looking into this.

Stopping hald brings hdparm from 18.5MB/s to 20MB/s, which is
indeed a noticeable improvement, though still far from the FC3
performance. I'm unsure what else can be stopped however
from this process list:

[root@donkey init.d]# ps ax
PID TTY STAT TIME COMMAND
1 ? S 0:00 init [3]
2 ? SN 0:00 [ksoftirqd/0]
3 ? S 0:00 [watchdog/0]
4 ? S< 0:00 [events/0]
5 ? S< 0:00 [khelper]
6 ? S< 0:00 [kthread]
8 ? S< 0:00 [kblockd/0]
11 ? S< 0:00 [khubd]
40 ? S 0:00 [kapmd]
72 ? S 0:00 [pdflush]
73 ? S 0:00 [pdflush]
74 ? S 0:00 [kswapd0]
75 ? S< 0:00 [aio/0]
76 ? S 0:00 [cifsoplockd]
77 ? S 0:00 [cifsdnotifyd]
153 ? S< 0:00 [kseriod]
186 ? S 0:00 [kedac]
199 ? S 0:00 [kjournald]
274 ? S<s 0:00 /sbin/udevd -d
346 ? S< 0:00 [kpsmoused]
781 ? S< 0:00 [scsi_eh_0]
782 ? S< 0:00 [usb-storage]
836 ? S 0:00 [kjournald]
838 ? S 0:00 [kjournald]
840 ? S 0:00 [kjournald]
842 ? S 0:00 [kjournald]
844 ? S 0:00 [kjournald]
1170 ? Ss 0:00 syslogd -m 0
1173 ? Ss 0:00 klogd -x
1197 ? Ss 0:00 portmap
1216 ? Ss 0:00 rpc.statd
1295 ? Ss 0:00 /usr/sbin/apmd -p 10 -w 5 -W -P
/etc/sysconfig/apm-sc 1440 ? Ss 0:00 cupsd
1480 ? Ss 0:00 /usr/sbin/sshd
1504 ? Ss 0:00 sendmail: accepting connections
1514 ? Ss 0:00 sendmail: Queue runner@01:00:00 for
/var/spool/client 1524 ? Ss 0:00 gpm -m /dev/input/mice -t
exps2
1533 ? Ss 0:00 crond
1582 ? Ss 0:00 /usr/sbin/atd
1662 tty1 Ss+ 0:00 /sbin/mingetty tty1
1663 tty2 Ss+ 0:00 /sbin/mingetty tty2
1666 tty3 Ss+ 0:00 /sbin/mingetty tty3
1669 tty4 Ss+ 0:00 /sbin/mingetty tty4
1672 tty5 Ss+ 0:00 /sbin/mingetty tty5
1703 tty6 Ss+ 0:00 /sbin/mingetty tty6
1718 ? Ss 0:00 sshd: root@pts/0
1742 pts/0 Ss 0:00 -bash
1859 pts/0 R+ 0:00 ps ax

strace shows read() system time practically identical around 1.3s,
hence I ran a ltrace comparison, which shows this:

FC3:

[root@donkey ~]# ltrace -c dd if=/dev/hdb of=/dev/null skip=400
bs=1024k count=200
200+0 records in
200+0 records out
% time seconds usecs/call calls function
------ ----------- ----------- --------- --------------------
99.86 14.597554 72987 200 read
0.10 0.015150 75 200 write
0.01 0.000947 473 2 dcgettext
0.01 0.000871 435 2 fprintf
0.00 0.000634 634 1 setlocale

FC5:

[root@donkey ~]# ltrace -c dd if=/dev/hdb of=/dev/null skip=400
bs=1024k count=200
200+0 records in
200+0 records out
209715200 bytes (210 MB) copied, 9.49944 seconds, 22.1 MB/s
% time seconds usecs/call calls function
------ ----------- ----------- --------- --------------------
99.81 27.460675 137303 200 read
0.12 0.032411 32411 1 dcgettext
0.05 0.014069 70 200 write
0.00 0.000908 302 3 __fprintf_chk

FC5 rebooted, with hald stopped:

[root@donkey init.d]# ltrace -c dd if=/dev/hdb of=/dev/null skip=400
bs=1024k count=200
200+0 records in
200+0 records out
209715200 bytes (210 MB) copied, 8.83107 seconds, 23.7 MB/s
% time seconds usecs/call calls function
------ ----------- ----------- --------- --------------------
99.93 26.791861 133959 200 read
0.05 0.014154 70 200 write
0.00 0.000925 925 1 dcgettext
0.00 0.000856 285 3 __fprintf_chk


Note the usecs/call comparison for read()...

[Also note how the ltrace output is wrong in terms of absolute
timing - approximately 3x the actual elapsed time]

Thanks,

--alessandro

"Dreamer ? Each one of us is a dreamer. We just push it down deep because
we are repeatedly told that we are not allowed to dream in real life"
(Reinhold Ziegler)
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