Re: how can i limit system resources for a particular process?
On Thu, Jul 02, 2009 at 04:26:14PM +0200, Jordi Moles Blanco wrote:
> I would like to run dd and let it use, for example, only 10% of the
> CPU time or 30% of the total amount of memory. Is that possible? I'm
> not looking for a "general" process limit for the whole system, only
> for a particular process.
Part of your question is about memory. AFAICT, the memory consumed by dd
is strictly a function of its block size, so just specify a blocksize
that fits within available RAM and doesn't cause filesystem writes to
block too long.
You might need to experiment a bit with this. For example, the following
are functionally equivalent in that they both create a 1GB file in /tmp,
but one of them may work better on your system than the other, depending
on a variety of hardware characteristics:
dd if=/dev/zero of=/tmp/zeroes bs=1M count=1000
dd if=/dev/zero of=/tmp/zeroes bs=256k count=4000
As for the rest of your question, most utilities like nice or cpulimit
operate on CPU usage, but your problem sounds like it's actually disk
I/O. I'd recommend installing util-linux if it isn't already on your
system, and using the ionice utility with "idle" priority.
You can even combine this with nice, if you want. Thus:
nice -n18 ionice -c3 dd if=/dev/zero of=/tmp/zeroes bs=1M count=1000
will probably take a longer time to complete, but your system should be
extremely responsive the whole time.
--
"Oh, look: rocks!"
-- Doctor Who, "Destiny of the Daleks"
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