* Re: Update on disk IO slowdown using udev
2004-05-25 10:46 Update on disk IO slowdown using udev Ake
@ 2004-05-25 10:58 ` Harald Hoyer
2004-05-25 11:14 ` Ake
` (7 subsequent siblings)
8 siblings, 0 replies; 10+ messages in thread
From: Harald Hoyer @ 2004-05-25 10:58 UTC (permalink / raw)
To: linux-hotplug
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Try it the other way round. I guess the data is cached :)
Use bonnie or hdparm -Tt to measure throughput!
Ake wrote:
> Hi!
> After some more experimenting i did the following,
>
> mkdir /tmpfsdev
> mount -t tmpfs tmpfs /tmpfsdev
> mknod /tmpfsdev/sdb b 8 16 (This is my test disk)
> dd if=/tmpfsdev/sdb of=/dev/null bs=8192k count=20
> 20+0 records in
> 20+0 records out
> 167772160 bytes transferred in 11.006714 seconds (15242711 bytes/sec)
>
> mkdir /rawdev
> mknod /rawdev/sdb b 8 16
> dd if=/rawdev/sdb of=/dev/null bs=8192k count=20
> 20+0 records in
> 20+0 records out
> 167772160 bytes transferred in 1.668631 seconds (100544793 bytes/sec)
>
>
> So tmpfs is the culprit.
> So, yes using udev i DO get a slowdown due to its use of tmpfs.
>
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^ permalink raw reply [flat|nested] 10+ messages in thread* Re: Update on disk IO slowdown using udev
2004-05-25 10:46 Update on disk IO slowdown using udev Ake
2004-05-25 10:58 ` Harald Hoyer
@ 2004-05-25 11:14 ` Ake
2004-05-25 12:01 ` Harald Hoyer
` (6 subsequent siblings)
8 siblings, 0 replies; 10+ messages in thread
From: Ake @ 2004-05-25 11:14 UTC (permalink / raw)
To: linux-hotplug
On Tue, May 25, 2004 at 12:58:36PM +0200, Harald Hoyer wrote:
> Try it the other way round. I guess the data is cached :)
> Use bonnie or hdparm -Tt to measure throughput!
>
> Ake wrote:
> >Hi!
> >After some more experimenting i did the following,
> >
> >mkdir /tmpfsdev
> >mount -t tmpfs tmpfs /tmpfsdev
> >mknod /tmpfsdev/sdb b 8 16 (This is my test disk)
> >dd if=/tmpfsdev/sdb of=/dev/null bsÅ92k count
> >20+0 records in
> >20+0 records out
> >167772160 bytes transferred in 11.006714 seconds (15242711 bytes/sec)
> >
> >mkdir /rawdev
> >mknod /rawdev/sdb b 8 16
> >dd if=/rawdev/sdb of=/dev/null bsÅ92k count
> >20+0 records in
> >20+0 records out
> >167772160 bytes transferred in 1.668631 seconds (100544793 bytes/sec)
To prove my point.
reboot
dd if=/rawdev/sdb of=/dev/null bsÅ92k count
20+0 records in
20+0 records out
167772160 bytes transferred in 1.572609 seconds (106683964 bytes/sec)
mount -t tmpfs tmpfs /tmpfsdev
mknod /tmpfsdev/sdb b 8 16
dd if=/tmpfsdev/sdb of=/dev/null bsÅ92k count
20+0 records in
20+0 records out
167772160 bytes transferred in 10.733471 seconds (15630746 bytes/sec)
There is no filesystem on this device so bonnie is no good.
ido-i [/]# hdparm -Tt /rawdev/sdb
/rawdev/sdb:
Timing buffer-cache reads: 2276 MB in 2.00 seconds = 1137.60 MB/sec
Timing buffered disk reads: 292 MB in 3.01 seconds = 97.15 MB/sec
ido-i [/]# hdparm -Tt /tmpfsdev/sdb
/tmpfsdev/sdb:
Timing buffer-cache reads: 2276 MB in 2.00 seconds = 1137.04 MB/sec
Timing buffered disk reads: 42 MB in 3.01 seconds = 13.94 MB/sec
--
Ake Sandgren, HPC2N, Umea University, S-90187 Umea, Sweden
Internet: ake@hpc2n.umu.se Phone: +46 90 7866134 Fax: +46 90 7866126
Mobile: +46 70 7716134 WWW: http://www.hpc2n.umu.se
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^ permalink raw reply [flat|nested] 10+ messages in thread* Re: Update on disk IO slowdown using udev
2004-05-25 10:46 Update on disk IO slowdown using udev Ake
2004-05-25 10:58 ` Harald Hoyer
2004-05-25 11:14 ` Ake
@ 2004-05-25 12:01 ` Harald Hoyer
2004-05-25 12:05 ` Harald Hoyer
` (5 subsequent siblings)
8 siblings, 0 replies; 10+ messages in thread
From: Harald Hoyer @ 2004-05-25 12:01 UTC (permalink / raw)
To: linux-hotplug
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Ake wrote:
> To prove my point.
>
> reboot
>
> dd if=/rawdev/sdb of=/dev/null bs=8192k count=20
> 20+0 records in
> 20+0 records out
> 167772160 bytes transferred in 1.572609 seconds (106683964 bytes/sec)
>
> mount -t tmpfs tmpfs /tmpfsdev
> mknod /tmpfsdev/sdb b 8 16
> dd if=/tmpfsdev/sdb of=/dev/null bs=8192k count=20
> 20+0 records in
> 20+0 records out
> 167772160 bytes transferred in 10.733471 seconds (15630746 bytes/sec)
>
>
> There is no filesystem on this device so bonnie is no good.
>
> ido-i [/]# hdparm -Tt /rawdev/sdb
>
> /rawdev/sdb:
> Timing buffer-cache reads: 2276 MB in 2.00 seconds = 1137.60 MB/sec
> Timing buffered disk reads: 292 MB in 3.01 seconds = 97.15 MB/sec
>
> ido-i [/]# hdparm -Tt /tmpfsdev/sdb
>
> /tmpfsdev/sdb:
> Timing buffer-cache reads: 2276 MB in 2.00 seconds = 1137.04 MB/sec
> Timing buffered disk reads: 42 MB in 3.01 seconds = 13.94 MB/sec
>
>
Ok... you got a point! very odd!
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^ permalink raw reply [flat|nested] 10+ messages in thread* Re: Update on disk IO slowdown using udev
2004-05-25 10:46 Update on disk IO slowdown using udev Ake
` (2 preceding siblings ...)
2004-05-25 12:01 ` Harald Hoyer
@ 2004-05-25 12:05 ` Harald Hoyer
2004-05-25 12:49 ` Harald Hoyer
` (4 subsequent siblings)
8 siblings, 0 replies; 10+ messages in thread
From: Harald Hoyer @ 2004-05-25 12:05 UTC (permalink / raw)
To: linux-hotplug
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Ake wrote:
>
> ido-i [/]# hdparm -Tt /rawdev/sdb
>
> /rawdev/sdb:
> Timing buffer-cache reads: 2276 MB in 2.00 seconds = 1137.60 MB/sec
> Timing buffered disk reads: 292 MB in 3.01 seconds = 97.15 MB/sec
>
> ido-i [/]# hdparm -Tt /tmpfsdev/sdb
>
> /tmpfsdev/sdb:
> Timing buffer-cache reads: 2276 MB in 2.00 seconds = 1137.04 MB/sec
> Timing buffered disk reads: 42 MB in 3.01 seconds = 13.94 MB/sec
>
>
what about ramfs??
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^ permalink raw reply [flat|nested] 10+ messages in thread* Re: Update on disk IO slowdown using udev
2004-05-25 10:46 Update on disk IO slowdown using udev Ake
` (3 preceding siblings ...)
2004-05-25 12:05 ` Harald Hoyer
@ 2004-05-25 12:49 ` Harald Hoyer
2004-05-25 18:01 ` Ake
` (3 subsequent siblings)
8 siblings, 0 replies; 10+ messages in thread
From: Harald Hoyer @ 2004-05-25 12:49 UTC (permalink / raw)
To: linux-hotplug
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ok, I can reproduce it. FC2 kernel 2.6.5-1.358
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^ permalink raw reply [flat|nested] 10+ messages in thread* Re: Update on disk IO slowdown using udev
2004-05-25 10:46 Update on disk IO slowdown using udev Ake
` (4 preceding siblings ...)
2004-05-25 12:49 ` Harald Hoyer
@ 2004-05-25 18:01 ` Ake
2004-05-25 18:19 ` Oliver Neukum
` (2 subsequent siblings)
8 siblings, 0 replies; 10+ messages in thread
From: Ake @ 2004-05-25 18:01 UTC (permalink / raw)
To: linux-hotplug
On Tue, May 25, 2004 at 02:05:44PM +0200, Harald Hoyer wrote:
> what about ramfs??
ramfs has exactly the same problem.
--
Ake Sandgren, HPC2N, Umea University, S-90187 Umea, Sweden
Internet: ake@hpc2n.umu.se Phone: +46 90 7866134 Fax: +46 90 7866126
Mobile: +46 70 7716134 WWW: http://www.hpc2n.umu.se
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^ permalink raw reply [flat|nested] 10+ messages in thread* Re: Update on disk IO slowdown using udev
2004-05-25 10:46 Update on disk IO slowdown using udev Ake
` (5 preceding siblings ...)
2004-05-25 18:01 ` Ake
@ 2004-05-25 18:19 ` Oliver Neukum
2004-05-25 18:42 ` Olaf Hering
2004-05-25 19:58 ` Oliver Neukum
8 siblings, 0 replies; 10+ messages in thread
From: Oliver Neukum @ 2004-05-25 18:19 UTC (permalink / raw)
To: linux-hotplug
Am Dienstag, 25. Mai 2004 14:49 schrieb Harald Hoyer:
> ok, I can reproduce it. FC2 kernel 2.6.5-1.358
That is very very odd. Is there anything running in the background?
To rule out the obvious, dd opens the devices only once, doesn't it?
Regards
Oliver
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^ permalink raw reply [flat|nested] 10+ messages in thread* Re: Update on disk IO slowdown using udev
2004-05-25 10:46 Update on disk IO slowdown using udev Ake
` (6 preceding siblings ...)
2004-05-25 18:19 ` Oliver Neukum
@ 2004-05-25 18:42 ` Olaf Hering
2004-05-25 19:58 ` Oliver Neukum
8 siblings, 0 replies; 10+ messages in thread
From: Olaf Hering @ 2004-05-25 18:42 UTC (permalink / raw)
To: linux-hotplug
On Tue, May 25, Oliver Neukum wrote:
> Am Dienstag, 25. Mai 2004 14:49 schrieb Harald Hoyer:
> > ok, I can reproduce it. FC2 kernel 2.6.5-1.358
>
> That is very very odd. Is there anything running in the background?
> To rule out the obvious, dd opens the devices only once, doesn't it?
just try it yourself. init=/bin/bash is enough. its scsi only.
you better bring that to lkml.
--
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sUse lINUX ag, n√úRNBERG
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^ permalink raw reply [flat|nested] 10+ messages in thread* Re: Update on disk IO slowdown using udev
2004-05-25 10:46 Update on disk IO slowdown using udev Ake
` (7 preceding siblings ...)
2004-05-25 18:42 ` Olaf Hering
@ 2004-05-25 19:58 ` Oliver Neukum
8 siblings, 0 replies; 10+ messages in thread
From: Oliver Neukum @ 2004-05-25 19:58 UTC (permalink / raw)
To: linux-hotplug
Am Dienstag, 25. Mai 2004 20:42 schrieb Olaf Hering:
> On Tue, May 25, Oliver Neukum wrote:
>
> > Am Dienstag, 25. Mai 2004 14:49 schrieb Harald Hoyer:
> > > ok, I can reproduce it. FC2 kernel 2.6.5-1.358
> >
> > That is very very odd. Is there anything running in the background?
> > To rule out the obvious, dd opens the devices only once, doesn't it?
>
> just try it yourself. init=/bin/bash is enough. its scsi only.
> you better bring that to lkml.
Using an USB memory stick I see sys time fall by 50%.
Mightily odd.
Regards
Oliver
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^ permalink raw reply [flat|nested] 10+ messages in thread