Re: Rik`s ac12-pmap2 vs ac12-vanilla perfcomp

Marcelo Tosatti (marcelo@conectiva.com.br)
Mon, 3 Sep 2001 12:22:26 -0300 (BRT)


On Sun, 2 Sep 2001, Daniel Phillips wrote:

> On September 2, 2001 11:46 pm, Samium Gromoff wrote:
> > Daniel Phillips wrote:
> > > > One thing that goes away with rmaps is the need to scan process page tables.
> > > It's possible that this takes enough load off L1 cache to produce the effects
> >
> > I feel like that.
> > actually there was a fear that the overhead of reverse map maintenance
> > will overthrow the gain on low loads, but in my case this isnt an issue.
>
> Rik's patch can be optimized a lot by using a direct pointer to the pte in the
> nonshared case, and perhaps a null rmap pointer in the kernel-only case (e.g.,
> page cache). If the non-optimized version is already performing better than the
> traditional approach it's a very good sign. This needs careful confirmation.
>
> Measurements where you force your system into continuous swapping would be very
> interesting.

Indeed.

Samium, I would appreciated if you could run heavy anon mem tests with
Rik's code. (eg programs from the memtest suite, make -jALOT, etc)

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