Re: Support for SIGSTOP/SIGCONT in nice?

[Andreas Schwab]

Simon Josefsson <address@hidden> writes:

> Frequently when I want to run a long-running I/O-bound job (i.e.,
> rsync of the entire disk to a second disk) on a busy machine (i.e.,
> mail and web server), the load increases to ~10 from a normal <1.

Assuming you are running on Linux, this is because there are about 10
processes waiting for disk I/O.

> Using 'nice' doesn't help.  I don't know why this is, but I suspect
> the kernel scheduler is sub-optimal for disk-bound jobs.

You probably want to change the I/O scheduling class for the process.
This can be done with ionice (which is Linux specific, included in the
util-linux package at least on SL 10.1).

Andreas.

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Andreas Schwab, SuSE Labs, address@hidden
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