Messages in this thread | | | Date | Tue, 18 Nov 2003 14:26:34 +0100 | From | Pavel Machek <> | Subject | Re: [PATCH] cfq + io priorities |
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Hi!
> > OTOH it might make sense to make "nice" command set > > both by default. > > Yes, I can probably be talked into that.
Good.
> > > > > 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...
Well, traditional (== scheduler) solution is not to have idle classes and not guarantee anything about realtime classes.
At least idle class can not be used to hold important semaphore forever (even low-priority prosses receive enough time not to hold important semaphores too long)... I believe you should do the same (== get rid of idle class for now, and clearly state that realtime ones are not _guaranteed_ anything). Pavel -- When do you have a heart between your knees? [Johanka's followup: and *two* hearts?] - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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