Messages in this thread | | | Subject | Re: unexpected paging during large file reads in 2.1.127 | From | Zlatko Calusic <> | Date | 12 Nov 1998 23:45:42 +0100 |
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Rik van Riel <H.H.vanRiel@phys.uu.nl> writes:
> On 12 Nov 1998, Zlatko Calusic wrote: > > "David J. Fred" <djf@ic.net> writes: > > > > > Summary: When doing large file reads from disk the system pages > > > unexpectedly causing moderate to severe degradation in I/O > > > and overall system performance even though there is plenty of > > > memory. > > > > Page cache is definitely too aggressive on recent kernels. I > > developed a small patch that avoids excessive swapouts. It helps > > kswapd to have less trouble reusing pages from page cache. > > Agreed, we should do something about that. > > > + age_page(page); > > + age_page(page); > > age_page(page); > > Do I hear "priority paging"? :)) > > > count_max = (limit<<2) >> (priority>>1); > > count_min = (limit<<2) >> (priority); > > Maybe increasing these has the same effect but with > the advantage of keeping page aging intact. >
Maybe, but then again maybe not.
I have a feeling that change like that could easily make kswapd a CPU pig.
We are aging pages, so that they don't get reaped easily, and then trying to compensate that with heavier scanning. Doesn't sound like a good idea. Sizif's job.
But still, looks interesting, so I'm just going to compile one test kernel with bigger count limits, for the fun's sake... :)
[Cc: Linux-MM]
Regards, -- Posted by Zlatko Calusic E-mail: <Zlatko.Calusic@CARNet.hr> --------------------------------------------------------------------- A chicken is an egg's way of producing more eggs.
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