Messages in this thread | | | Date | Thu, 10 Jul 2003 15:57:47 +0200 | From | Jens Axboe <> | Subject | Re: RFC on io-stalls patch |
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On Tue, Jul 08 2003, Marcelo Tosatti wrote: > > Hello people, > > To get better IO interactivity and to fix potential SMP IO hangs (due to > missed wakeups) we, (Chris Mason integrated Andrea's work) added > "io-stalls-10" patch in 2.4.22-pre3. > > The "low-latency" patch (which is part of io-stalls-10) seemed to be a > good approach to increase IO fairness. Some people (Alan, AFAIK) are a bit > concerned about that, though. > > Could you guys, Stephen, Andrew and maybe Viro (if interested :)) which > havent been part of the discussions around the IO stalls issue take a look > at the patch, please? > > It seems safe and a good approach to me, but might not be. Or have small > "glitches".
Well, I have one naive question. What prevents writes from eating the entire request pool now? In the 2.2 and earlier days, we reserved the last 3rd of the requests to writes. 2.4.1 and later used a split request list to make that same guarentee.
I only did a quick read of the patch so maybe I'm missing the new mechanism for this. Are we simply relying on fair (FIFO) request allocation and oversized queue to do its job alone?
-- Jens Axboe
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