how can i limit system resources for a particular process?

Nils Kassube kassube at gmx.net
Thu Jul 2 16:31:41 BST 2009


Jordi Moles Blanco wrote:
> let's say i want to create an .img file of 50GB with "dd" command.
> After that, i will give it a format with mkfs.ext3.
>
> The problem is that while "dd" is running I'm not able to do anything
> else on the machine, not even ssh in, it just consumes all the
> available resources, and as I'm creating a 50GB image, i can't access
> the machine for several minutes.
>
> I've tried to use "nice" command, giving the "dd" process the lowest
> possible priority, 19. The thing is that the whole thing performs
> better, i can establish ssh connection. However, i can't do much when
> I'm in it, everything is so slow.

Try the ionice command. In your case the problem is the constant write 
access to the disk. If you want to limit disk access to times where no 
other process wants to use the disk, it would be a command like this:

ionice -c3 dd if=/dev/zero of=filename.img bs=10M count=5000

You can even combine it with nice like

nice -19 ionice -c3 dd if=/dev/zero of=filename.img bs=10M count=5000

but I don't think that is necessary.


Nils




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