Messages in this thread | | | Date | Fri, 8 Jan 1999 22:44:25 -0800 (PST) | From | Linus Torvalds <> | Subject | Re: 2.2.0-pre[56] swap performance poor with > 1 thrashing task |
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Btw, if there are people there who actually like timing different things (something I _hate_ doing - I lose interest if things become just a matter of numbers rather than trying to get some algorithm right), then there's one thing I'd love to hear about: the effect of trying to do some access bit setting on buffer cache pages.
See my comments in linux/include/linux/fs.h, at around line 260 or so. It's the "touch_buffer()" macro which is currently a no-op, and it is entirely possible that it really should set the PG_referenced bit.
As a no-op, it can now randomly and unprectably result in even worthwhile buffers just being thrown out - possibly quite soon after they've been loaded in. I happen to believe that it doesn't actually matter (and I'm not convinced that marking the pages referenced has no downsides), but I'm too lazy to bother to test it.
Linus
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