Comment 164 for bug 215728

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!