Re: [PATCH] (2/2) reverse mappings for current 2.5.23 VM

Daniel Phillips
2002-06-19T20:44:06Z

On Wednesday 19 June 2002 22:09, Craig Kulesa wrote:
> I wouldn't draw _any_ conclusions about either patch yet, because as you
> said, it's only one type of load. And it was a single tick in vmstat
> where page_launder() was aggressive that made the difference between the
> two. In a different test, where I had actually *used* more of the
> application pages instead of simply closing most of the applications
> (save one, the memory hog), the results are likely to have been very
> different.
>
> I think that Rik's right: this simply points out that page_launder(), at
> least in its interaction with 2.5, needs some tuning. I think both
> approaches look very promising, but each for different reasons.

Indeed.

One reason for being interested in a lot more numbers and a variety of loads
is that there's an effect, predicted by Andea, that I'm watching for: both
aging+rmap and lru+rmap do swapout in random order with respect to virtual
memory, and this should in theory cause increased seeking on swap-in. We
didn't see any sign of such degradation vs mainline, in fact we saw a
significant overall speedup. It could be we just haven't got enough data
yet, or maybe there really is more seeking for each swap-in, but the effect
of less swapping overall is dominant.

--
Daniel