Re: large files

[Bernd Schubert <bernd-schubert@web.de>]

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Hello Chris,

>
> As a comparison data point, could you please try 2.6.6-mm3?  I realize
> you don't want to run this kernel in production, but it would tell us if
> I understand the problems at hand.

the results in 2.6.6-mm3 are below, we almost consider to run this kernel 
version.

Here are two other interesting facts:

1.) During the filecreation in 2.4.26 the load on the system was around 3-4, 
whereas in 2.6.6-mm3 the load was at about 8-9.

2.) When the dd file creation process finished (2.4.26 was running) the system 
became so unresponsible, that the drdb connection timed out and a resync 
process automatically started when the system became responsible again. I 
don't have any comparism to 2.6.6-mm3 since we would need another drbd 
version. Also, I don't know if this happend when dd finished or when 
rm-started, since both were running from a script.

Here are the measured times for file creation and file deleting

=====> 2.4.26:

taylor:~# cat test.out-2.4.26
time dd if=/dev/zero of=/worka/testfile.dd bs=1M count=300000
300000+0 records in
300000+0 records out
314572800000 bytes transferred in 5746.266841 seconds (54743855 bytes/sec)

real	95m46.275s
user	0m0.760s
sys	29m57.800s


time rm -fr /worka/testfile.dd

real	11m20.589s
user	0m0.000s
sys	4m59.850s


=====> 2.6.6-mm3


taylor:~# cat test.out-2.6.6-mm3
time dd if=/dev/zero of=/worka/testfile.dd bs=1M count=300000
300000+0 records in
300000+0 records out
314572800000 bytes transferred in 4902.873869 seconds (64160900 bytes/sec)

real	81m46.211s
user	0m1.172s
sys	22m26.010s


time rm -fr /worka/testfile.dd

real	1m38.000s
user	0m0.000s
sys	1m5.872s



Do you have any ideas how we could improve 2.4.x? 


Thanks,
	Bernd


-- 
Bernd Schubert
Physikalisch Chemisches Institut / Theoretische Chemie
Universität Heidelberg
INF 229
69120 Heidelberg
e-mail: bernd.schubert@pci.uni-heidelberg.de

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