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From: Bartlomiej Zolnierkiewicz <B.Zolnierkiewicz@elka.pw.edu.pl>
To: "Svetoslav Slavtchev" <svetljo@gmx.de>,
       "Carlos Fernandez Sanz" <cfs-lk@nisupu.com>
Subject: Re: HighPoint 374
Date: Mon, 20 Oct 2003 23:25:05 +0200
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multicount affects PIO transfers performance only...

On Monday 20 of October 2003 23:07, Svetoslav Slavtchev wrote:
> > BTW, isn't m0 supposed to reduce perfomance?
>
> hm here it also doesn't seem to change much,
> may be it's ignored if UDMA is used
>
> mem is 1024Mb
>
> [root@svetljo kernel]#  hdparm -m0 /dev/hde
>
> /dev/hde:
>  setting multcount to 0
>  multcount    =  0 (off)
>
> [root@svetljo 1]# time dd if=/dev/zero of=10Gb.zeros count=20000 bs=512k
> 20000+0 records in
> 20000+0 records out
> 0.09user 29.38system 5:44.49elapsed 8%CPU (0avgtext+0avgdata 0maxresident)k
> 0inputs+0outputs (149major+40minor)pagefaults 0swaps
> [root@svetljo 1]#  hdparm -m8 /dev/hde
>
> /dev/hde:
>  setting multcount to 8
>  multcount    =  8 (on)
> [root@svetljo 1]# time dd if=/dev/zero of=10Gb.zeros count=20000 bs=512k
> 20000+0 records in
> 20000+0 records out
> 0.10user 28.99system 5:50.44elapsed 8%CPU (0avgtext+0avgdata 0maxresident)k
> 0inputs+0outputs (150major+41minor)pagefaults 0swaps
>
> root@svetljo 1]#  hdparm -m16 /dev/hde
>
> /dev/hde:
>  setting multcount to 16
>  multcount    = 16 (on)
> [root@svetljo 1]# time dd if=/dev/zero of=10Gb.zeros count=20000 bs=512k
> 20000+0 records in
> 20000+0 records out
> 0.09user 28.83system 5:53.57elapsed 8%CPU (0avgtext+0avgdata 0maxresident)k
> 0inputs+0outputs (165major+40minor)pagefaults 0swaps
> [root@svetljo 1]#
>
> > [root@fulanito wd1200jb]# time dd if=/dev/zero of=filling count=20000
> > bs=65536
> > 20000+0 records in
> > 20000+0 records out
> >
> > real    0m33.763s
> > user    0m0.200s
> > sys     0m10.920s
> > [root@fulanito wd1200jb]# hdparm -m4 /dev/hdk
> >
> > /dev/hdk:
> >  setting multcount to 4
> >  multcount    =  4 (on)
> > [root@fulanito wd1200jb]# time dd if=/dev/zero of=filling count=20000
> > bs=65536
> > 20000+0 records in
> > 20000+0 records out
> >
> > real    0m30.321s
> > user    0m0.150s
> > sys     0m10.630s
> > [root@fulanito wd1200jb]# hdparm -m0 /dev/hdk
> >
> > /dev/hdk:
> >  setting multcount to 0
> >  multcount    =  0 (off)
> > [root@fulanito wd1200jb]# time dd if=/dev/zero of=filling count=20000
> > bs=65536
> > 20000+0 records in
> > 20000+0 records out
> >
> > real    0m30.749s
> > user    0m0.130s
> > sys     0m10.900s
> > [root@fulanito wd1200jb]#