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From: Pieter de Goeje <pieter@degoeje.nl>
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Subject: Re: svn commit: r221853 - in head/sys: dev/md dev/null sys vm
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On Sunday 29 May 2011 05:01:57 mdf@freebsd.org wrote:
> On Sat, May 28, 2011 at 12:03 PM, Pieter de Goeje <pieter@degoeje.nl> wrote:
> > To me it looks like it's not able to cache the zeroes anymore. Is this
> > intentional? I tried to change ZERO_REGION_SIZE back to 64K but that
> > didn't help.
>
> Hmm.  I don't have access to my FreeBSD box over the weekend, but I'll
> run this on my box when I get back to work.
>
> Meanwhile you could try setting ZERO_REGION_SIZE to PAGE_SIZE and I
> think that will restore things to the original performance.

Indeed it does. I couldn't find any authoritative docs stating wether or not 
the cache on this CPU is virtually indexed, but apparently at least some of 
it is.

Regards,

Pieter