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Date:      Sat, 14 Aug 1999 06:50:08 +0900
From:      Hidetoshi Shimokawa <simokawa@sat.t.u-tokyo.ac.jp>
To:        alc@cs.rice.edu
Cc:        rgrimes@gndrsh.aac.dev.com, cvs-committers@freebsd.org, cvs-all@freebsd.org
Subject:   Re: cvs commit: src/sys/vm vm_page.h
Message-ID:  <14260.37648.315208.25254T@ett.sat.t.u-tokyo.ac.jp>
In-Reply-To: In your message of "Fri, 13 Aug 1999 15:33:31 -0500" <19990813153331.C26372@nonpc.cs.rice.edu>
References:  <199908122116.OAA56955@freefall.freebsd.org> <199908131458.HAA01346@gndrsh.aac.dev.com> <19990813140128.C27982@cs.rice.edu> <14260.30905.562825.38243A@ett.sat.t.u-tokyo.ac.jp> <19990813153331.C26372@nonpc.cs.rice.edu>

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At Fri, 13 Aug 1999 15:33:31 -0500,
Alan Cox <alc@cs.rice.edu> wrote:
> 
> On Sat, Aug 14, 1999 at 04:57:45AM +0900, Hidetoshi Shimokawa wrote:
> > ...
> >
> > As for 21164 Alpha, it has 96KB 3-way L2 cache.
> > So it needs only 4 (= 96KB / 8KB / 3) colors.
> > 
> > My Alpha box has 4MB direct-map L3 cache and
> > it needs 4MB / 8KB = 512 colors. I have the following entries in my
> > vm_page.h
> > 
> 
> I am afraid that the current implementation of page coloring doesn't
> scale very well to such a large number of colors, especially if you
> don't have an extremely large amount of physical memory.  Far too often,

It could be. Last time I checked, 256 colors gives best user-time
while kernel-build benchmark.
My machine is with 512MB physical memory.

> it's unable to allocate a page of the appropriate color.  Even with
> just 8 colors on a machine with 320MB of physical memory, the number
> of times that coloring fails during a "make world" is extraordinary.

How do you detect 'coloring failure'?
By adding counter in vm_page_list_find?

> Bruce Evans and I are looking into this...if someone with an Alpha
> has time to help out that could be useful.

At least, alpha lacks pre-zeroed pages because vm_page_zero_idle is
not enabled...

-- 
/\ Hidetoshi Shimokawa
\/  simokawa@sat.t.u-tokyo.ac.jp
PGP public key: finger -l simokawa@sat.t.u-tokyo.ac.jp


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