Hi guys,
two useful methods to measure IO by process are the following, based on
the great SystemTap linux kernel tool.
The disktop.stp script, which can be found attached here, measure the
first N processes odered by IO activity - a 'top' for disk resource, we
could say. I've found it on the net, it seems to be made by Oracle and
it is the porting to SystemTap of the equivalent Dtrace script.
Once found the culprit process, we can also see the response time of
each IO request that the process make with the iotime.stp script, which
is provided with the systemtap package
(/usr/share/doc/systemtap/examples/iotime.stp)
I hope you can find them useful. Let us know if firefox is actually the
process that hurts your performance. I've noticed that in Ubuntu there
are also other very high disk demanding tool, for example the
scrollkeeper-update or the slocate db updater.
I think it should be paid more attention to the disk resource, often its
impact on performance is overlooked but actually it is important. If the
culprit process is a background tool, you can lower its IO priority with
ionice - thanks to the linux fair CFQ scheduler.
Let us know what you find!
** Attachment added: "disktop.stp"
http://launchpadlibrarian.net/14453679/disktop.stp
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[MASTER] Committing to urlclassifier3.sqlite causes excessive CPU usage and
disk I/O
https://bugs.launchpad.net/bugs/215728
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