Re: Performance under contention

Hi Tom

I suspect I may be missing something here, but I think it's a pretty
universal truism that cache lines are aligned to power-of-2 memory
addresses, so it would suffice to ensure during setup that the lower order n
bits of the object address are all zeros for each critical object; if the
malloc() routine being used doesn't support that, it could be done by
allocating a slightly larger than necessary block of memory and choosing a
location within that.

The value of n could be architecture dependent, but n=8 would cover
everyone, hopefully without wasting too much RAM.

Cheers
Dave

On Tue, Dec 7, 2010 at 11:50 AM, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:

>
> One thing that might be interesting, but that I don't know how to attack
> in a reasonably machine-independent way, is to try to ensure that shared
> and local data structures don't accidentally overlap within cache lines.
> When they do, you pay for fighting the cache line away from another
> processor even when there's no real need.
>
> regards, tom lane
>
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