Re: another approach to rss : sloppy rss

From: Robin Holt <holt_at_sgi.com>
Date: 2004-11-20 12:46:10
On Sat, Nov 20, 2004 at 12:24:17PM +1100, Nick Piggin wrote:
> Well, you still need to put those counters on seperate cachelines, so you
> still need to pad them out quite a lot. Then as they are shared, you _still_
> need to make them atomic, and they'll still be bouncing around too.
> 
> Linus' idea of a per-thread 'pages_in - pages_out' counter may prove to be
> just the right solution though.

I can go with either solution.  Not sure how many cpus we can group together
before the cacheline becomes so hot that we need to fan them out.  I have
a gut feeling it is alot.

On the 2.4 kernel which SGI put together, we just changed rss to an
atomic and ensured it was in a seperate cacheline from the locks and
performance was more than adequate.  I realize a lot has changed since
2.4, but the concepts are similar.

Just my 2 cents,
Robin
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Received on Fri Nov 19 20:48:55 2004

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