Re: Misaligned BufferDescriptors causing major performance problems on AMD - Mailing list pgsql-hackers

From Peter Geoghegan
Subject Re: Misaligned BufferDescriptors causing major performance problems on AMD
Date
Msg-id CAM3SWZSEXRSwJw=18CyBmOC5vt_kbEkoowEg2CRQzEH+tgMMrw@mail.gmail.com
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In response to Re: Misaligned BufferDescriptors causing major performance problems on AMD  (Andres Freund <andres@2ndquadrant.com>)
List pgsql-hackers
On Wed, Feb 5, 2014 at 7:21 AM, Andres Freund <andres@2ndquadrant.com> wrote:
> All current x86 processors use 64. But even if it were bigger/smaller,
> they will be either 32, or 128. Neither benefits from touching more
> cachelines than necessary. E.g. in the 128 case, we could still touch
> two with the current code.

That's true, but I believe that a hardware optimization called
Adjacent Cache Line Prefetch is widely supported by recent
microarchitectures, and is sometimes enabled by default. I'm not
suggesting that that would necessarily radically alter the outcome,
but it is a consideration.



-- 
Peter Geoghegan



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