Author: Gerd Isenberg
Date: 14:44:23 02/07/06
Go up one level in this thread
On February 07, 2006 at 16:28:53, h.g.muller wrote:
>I guess I misread your previous message, I thought you referred to the variable
>latency because of the initial access, but you were talking about the follow
>up... :-(
>
>I think it would be a good idea to align the hash table with cache-line
>boundaries so that this will not occur. In a 64-byte cache lines you could put
>four 16-byte entries, so that a single entrie never straddles a boundary. The
>rehashing scheme coud be designed such that you try all 4 entries in that cache
>line before trying anything else (or accept a failure):
>
>if(TP[hash].lock==key
> TP[hash^=16].lock==key ||
> TP[hash^=32].lock==key ||
> TP[hash^=16].lock==key)
>{/* process hit at TP[hash] */}
>else
>{/* process miss */}
very nice idea to traverse four 16-byte entries of a cacheline.
I actually do something like this...
if(TP[hash&=~63].lock==key ||
TP[hash+= 16].lock==key ||
TP[hash+= 16].lock==key ||
TP[hash+= 16].lock==key)
{/* process hit at TP[hash] */}
else
{/* process miss */}
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