Re: 2.4.23aa2 (bugfixes and important VM improvements for the highend)

[Marcelo Tosatti]

On Fri, 27 Feb 2004, Andrew Morton wrote:

> Oh, and can we please have testcases?  It's all very well to assert "it
> sucks doing X and I fixed it" but it's a lot more useful if one can
> distrubute testcases as well so others can evaluate the fix and can explore
> alternative solutions.
>
> Andrea, this shmem problem is a case in point, please.
>
> > > in small machines the current 2.4 stock algo works just fine too, it's
> > > only when the lru has the million pages queued that without my new vm
> > > algo you'll do million swapouts before freeing the memleak^Wcache.
> >
> > Same for Arjan's O(1) VM.  For machines in the single and low
> > double digit number of gigabytes of memory either would work
> > similarly well ...
>
> Case in point.  We went round the O(1) page reclaim loop a year ago and I
> was never able to obtain a testcase which demonstrated the problem on 2.4,
> let alone on 2.6.
>
> I had previously found some workloads in which the 2.4 VM collapsed for
> similar reasons and those were fixed with the rotate_reclaimable_page()
> logic.  Without testcases we will not be able to verify that anything else
> needs doing.

Btw,

Andrew, are your testcases online somewhere?

I heard once someone was going to collect VM tests to make a "official
testing package", but that has never happened AFAIK.

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