Messages in this thread | | | Date | Thu, 8 Mar 2007 20:51:02 -0600 | From | Anton Blanchard <> | Subject | Re: [patch] epoll use a single inode ... |
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> OK, 200 cycles... > > But what is the cost of the conditional branch you added in prefetch(x) ?
Much less than the tablewalk. On ppc64 a tablewalk of an address that is not populated in the hashtable will incur 2 cacheline lookups (primary and secondary buckets). This plus the MMU state machine overhead adds up.
Cue Linus rant about PowerPC MMU :)
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