Messages in this thread | | | Date | Fri, 8 Jan 1999 22:53:38 -0800 (PST) | From | Linus Torvalds <> | Subject | Re: 2.2.0-pre[56] swap performance poor with > 1 thrashing task |
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On Fri, 8 Jan 1999, Benjamin Redelings I wrote: > > Maybe this is not really a problem with swapping, but more with > concurrent I/O in general,
It's really easy to get really crappy performance with concurrent IO, if you end up just seeking back and forth on the disk - which is why we should be trying to cluster our IO. Sounds like we end up with silly behaviour where one process is paging in from one area of the disk while the other is paging out to another area, resulting in all the time spent in just moving the disk head rather than moving any actual data.
Or something silly like that. The fix is probably not all that complex: the code is supposed to try to avoid it, but I bet I just had some idiotic braino that just completely defeated the whole idea. It sounds like Zlatko found my braino already.
Linus
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