Messages in this thread | | | Subject | Re: Buffer handling (setting PG_referenced on access) | From | Zlatko Calusic <> | Date | 11 Jan 1999 21:14:11 +0100 |
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Linus Torvalds <torvalds@transmeta.com> writes:
> On 11 Jan 1999, Zlatko Calusic wrote: > > > > OK, implementation was easy and simple, much simpler than it was made > > before (with BH_Touched copying...), but I must admit that even after > > lots of testing I couldn't find any difference. Not in performance, > > not in CPU usage, not in overall behaviour. Whatever results I have > > accomplished, they were too much in the statistical noise, so I don't > > have any useful data. Maybe, others can try and see. > > This was what I saw in my very very inconclusive tests too - which is why > I decided that there was no point in doing buffer cache aging at all.
Yes, looks like we finished our tests with same results.
> > > But, nevertheless, four lines added to the kernel look very correct to > > me. My vote for including, if for nothing, then to make balance with > > page cache. It won't harm anything, that's for sure. > > I can easily see it harming something - I actually think that not using > the reference bit is "safer" in that it never allows the buffer cache to > grow very aggressively for very long (and we definitely don't want to have > an overlarge buffer cache - it's mostly used for temporary buffers for > write-out anyway). > > Basically I don't want to enable the aging code unless somebody shows me > that it makes a marked improvement under some (reasonably real-world) > circumstances.. So far the jury seems to say that it doesn't. >
OK, I got one more idea in the meantime, and I'll try it as the time permits. In the meantime, I agree with you. If we can't prove it's actually worthwhile to add those four lines, then we really don't need them.
Regards, -- Zlatko
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