Messages in this thread | | | Subject | Re: [PATCH] mm: Implement swap prefetching tweaks | From | Mike Galbraith <> | Date | Sun, 12 Mar 2006 06:27:36 +0100 |
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On Sat, 2006-03-11 at 23:54 -0500, Lee Revell wrote: > On Sat, 2006-03-11 at 08:51 +0100, Mike Galbraith wrote: > > There used to be a pages in flight 'restrictor plate' in there that > > would have probably helped this situation at least a little. But in > > any case, it sounds like you'll have to find a way to submit the IO in > > itty bitty synchronous pieces. > > echo 64 > /sys/block/hd*/queue/max_sectors_kb > > There is basically a straight linear relation between whatever you set > this to and the maximum scheduling latency you see. It was developed to > solve the exact problem you are describing.
Ah, a very useful bit of information, thanks.
It won't help Con though, because he'll be dealing with every possible configuration. I think he's going to have to either submit, wait, bandwidth limiting sleep, repeat or something clever that does that. Even with bandwidth restriction though, seek still bites mightily, so I suspect he's stuck with little trickles of IO started when we'd otherwise be idle. We'll see I suppose.
-Mike
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