Messages in this thread | | | Date | Mon, 17 Nov 2003 09:14:07 +0100 | From | Jens Axboe <> | Subject | Re: [PATCH] cfq + io priorities |
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On Thu, Nov 13 2003, Pavel Machek wrote: > Hi! > > > > OK, I ask THE question : why not using the normal nice level, via > > > current->static_prio ? > > > This way, cdrecord would be RT even in IO, and nice -19 updatedb would have > > > a minimal impact on the system. > > > > I don't want to tie io prioritites to cpu priorities, that's a design > > decision. > > OTOH it might make sense to make "nice" command set > both by default.
Yes, I can probably be talked into that.
> > > > these end values are "special" - 0 means the process is only allowed to > > > > do io if the disk is idle, and 20 means the process io is considered > > > > > > So a process with ioprio == 0 can be forever starved. As it's not > > > > Yes > > If semaphore is held over disk io somewhere (quota code? journaling?) > you have ugly possibility of priority inversion there.
Indeed yes. That's a general problem with all the io priorities though, RT io might end up waiting for nice 10 io etc. Dunno what to do about this yet...
-- Jens Axboe
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