Messages in this thread | | | From | Rob Landley <> | Subject | Re: [PATCH] O13int for interactivity | Date | Mon, 11 Aug 2003 02:57:25 -0400 |
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On Tuesday 05 August 2003 03:26, Con Kolivas wrote: > On Tue, 5 Aug 2003 16:03, Andrew Morton wrote: > > We do prefer that TASK_UNINTERRUPTIBLE processes are woken promptly so > > they can submit more IO and go back to sleep. Remember that we are > > artificially leaving the disk head idle in the expectation that the task > > will submit more I/O. It's pretty sad if the CPU scheduler leaves the > > anticipated task in the doldrums for five milliseconds. > > Indeed that has been on my mind. This change doesn't affect how long it > takes to wake up. It simply prevents tasks from getting full interactive > status during the period they are doing unint. sleep. > > > Very early on in AS development I was playing with adding "extra boost" > > to the anticipated-upon task, but it did appear that the stock scheduler > > was sufficiently doing the right thing anyway. > > Con
It seems that there's a special case, where a task that was blocked on a read (either from a file or from swap) wants to be scheduled immediately, but with a really short timeslice. I.E. give it the ability to submit another read and block on it immediately, but if a single jiffy goes by and it hasn't done it, it should go away.
This has nothing to do with the normal priority levels or being considered interactive or not. As I said, a special case. IO_UNBLOCKED_FLAG or some such. Maybe unnecessary...
(Once again, the percentage of CPU time to devote to a task and the immediacy of scheduling that task are in opposition. The "priority" abstraction is a bit too simple at times...)
Rob
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