Re: Making nice niser for system hogging programs

[Con Kolivas <kernel@kolivas.org>]

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On Sun, 2 Oct 2005 13:18, Marc Perkel wrote:
> Con Kolivas wrote:
> >On Sun, 2 Oct 2005 12:26, Marc Perkel wrote:
> >>Just a thought -----
> >>
> >>Programs like cp -a /bigdir /backup and rsync usually bring the server
> >>to a crawl no matter how much "nice" you put on them. Is there any way
> >>to make "nice" smarter in that it limits io as well as processor usage?
> >>If cp and rsyne ran a little slower IO wise then everything else could
> >>run too.
> >
> >The latest cfq io scheduler supports io nice levels. By default it links
> > the io nice levels to the cpu nice levels so if you use cfq and set your
> > file commands nice 19 they will use as little io priority as possible.
> > Note this only works on the read side but that makes a dramatic
> > difference already.
>
> Kewl - so - what version is it in?

2.6.13 already has it. Note that the io priority is only inherited when a 
process first starts so doing renice to something already running will only 
change the cpu nice, not the ionice. You can do that on the fly using the 
ionice application. If you look in the kernel source in 
Documentation/block/ioprio.txt you'll find the source to ionice.c 

Cheers,
Con

P.S. It is considered routine to reply-to-all when posting to lkml and not 
stripping anybody on the cc list.

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