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PostPosted: Wed Aug 20, 2008 8:42 am 
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Newbie

Joined: Tue May 29, 2007 10:49 pm
Posts: 2
Greetings
If I perform certain IO operations (such as deleting files) all other io operations nearly starve.

While deleting a 1gb file on the background, listing home directory files, ls ~ takes 10-15 seconds to complete:

Example:

create a file:
% dd if=/dev/zero of=testfile bs=1024M count=1

delete it on the background:
% rm testfile&

time ls of ~ (32 items on ~, mostly folders)
% time ls
...
ls -F --color=always 0.00s user 0.00s system 0% cpu 14.071 total

Is this typical?
Is there another disk IO scheduler available for install as a kernel module?


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PostPosted: Wed Aug 20, 2008 6:30 pm 
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Joined: Wed Mar 19, 2008 10:34 pm
Posts: 32
Website: http://www.claws-and-paws.com/
WLM: doug.muth@gmail.com
Yahoo Messenger: dmuthathome
AOL: Dmuth+At+Home
Location: Ardmore, PA
Just out of curiosity, have you tried nicing the rm job and/or running strace on the rm and/or the ls commands?

Seeing if there is a particular system call that is a bottleneck may provide useful information.

(Disclaimer: I am NOT an employee of Linode)


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PostPosted: Thu Aug 21, 2008 11:54 am 
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Joined: Mon Dec 10, 2007 4:30 pm
Posts: 341
Website: http://markwalling.org
Xen or UML?


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PostPosted: Mon Aug 25, 2008 2:10 am 
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Joined: Tue May 29, 2007 10:49 pm
Posts: 2
dmuth:
if I nice *and* ionice it seems to help a little, but the rm still takes ages.
ie: sudo nice -n 15 ionice -c3 rm foo

mwalling: xen


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PostPosted: Mon Aug 25, 2008 9:57 am 
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Joined: Wed Mar 19, 2008 10:34 pm
Posts: 32
Website: http://www.claws-and-paws.com/
WLM: doug.muth@gmail.com
Yahoo Messenger: dmuthathome
AOL: Dmuth+At+Home
Location: Ardmore, PA
@achille Have you tried running the rm under strace yet?


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