comments in the page coloring options in /sys/conf/NOTES
alc at cs.rice.edu
Sun Jun 6 20:12:54 GMT 2004
On Sun, Jun 06, 2004 at 02:24:46PM +0200, Alexander Leidinger wrote:
> the comments about the page coloring in the VM system seem to talk about
> L2/L1 cache size combinations, e.g. PQ_CACHESIZE=512 for a 512k/16k
> cache. The comment above the PQ_CACHESIZE line just talks about the size
> of the L2 cache.
> If it indeed talks about L2/L1 combinations, we should make it explicit.
> And what about a 512k/8k combination?
> If it just talks about the L2 cache size, what is the meaning of the
> second number?
My recent commit fixed a "syntax" error in the comments, specifically,
a reference to a missing macro. The comments are, however, still
1. Cache size alone does not correctly determine the number of colors,
except for direct map caches. The correct formula is
(cache size in bytes / page size in bytes) / degree of cache associativity
Thus, the comments would lead one to configure his/her system with too
many colors. (Relative to configuring a system with too few colors,
this is not so bad.)
2. The references to L1 should be removed. They are historical
To conclude, I would be thrilled if someone wanted to work on
automating this. I don't think it's reasonable to expect users to
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