From: Andi Kleen <ak@suse.de>
Date: Fri, 9 Nov 2001 07:39:46 +0100
I'm assuming that walking on average 5-10 pages on a lookup is not
too big a deal, especially when you use prefetch for the list walk.
Oh no, not this again...
It _IS_ a big deal. Fetching _ONE_ hash chain cache line
is always going to be cheaper than fetching _FIVE_ to _TEN_
page struct cache lines while walking the list.
Even if prefetch would kill all of this overhead (sorry, it won't), it
is _DUMB_ and _STUPID_ to bring those _FIVE_ to _TEN_ cache lines into
the processor just to lookup _ONE_ page.
Franks a lot,
David S. Miller
davem@redhat.com
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This archive was generated by hypermail 2b29 : Thu Nov 15 2001 - 21:00:21 EST