[concurrency-interest] padding in Exchanger

David Dice david.dice at gmail.com
Tue Jan 17 10:29:30 EST 2012


>
>
> For what it's worth, +1 on the annotation proposal.
>
> Curious - which i7 arch has 128 byte cache line? I know Netburst used to
> have 128 as a blocked pair of two 64 byte lines, but didn't see anything on
> the newer chips.
>
>
The line size and coherence unit is 64 bytes but adjacent sector prefetch
when enabled (sometimes a BIOS setting), can make the coherence unit
effectively 128 bytes, which is why I suggested extra padding to Doug.
 ASP is usually a good bet for single-threaded code, but occasionally it
can cause destructive interference, and it can be a challenge for MP code.


I think Intel officially recommends 128 bytes in their current optimization
manuals.

Dave
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