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Date:      Mon, 18 Mar 2002 09:54:17 -0500
From:      "Brian F. Feldman" <green@FreeBSD.ORG>
To:        Matthew Dillon <dillon@apollo.backplane.com>
Cc:        Hiten Pandya <hitmaster2k@yahoo.com>, current@FreeBSD.ORG, cvs-all@FreeBSD.ORG, cvs-committers@FreeBSD.ORG, tanimura@r.dl.itc.u-tokyo.ac.jp
Subject:   Re: cvs commit: src/sys/kern kern_mtxpool.c src/sys/sys kernel.h src/sys/vm vm_fault.c vm_glue.c vm_map.c vm_map.h vm_pageout.c vm_zone.c 
Message-ID:  <200203181454.g2IEsHE88877@green.bikeshed.org>
In-Reply-To: Your message of "Sun, 17 Mar 2002 16:48:24 PST." <200203180048.g2I0mOc40231@apollo.backplane.com> 

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Matthew Dillon <dillon@apollo.backplane.com> wrote:
> 
> :
> :Hi,
> :
> :Sorry to unwantedly butt in, but the patch supplied by Seigo actually
> :solved the vm_map.c locking problems which used to come up on my system.
> :Just some info. :)
> :
> :Regards,
> :
> :  -- Hiten Pandya
> :  -- <hiten@uk.FreeBSD.org>
> 
>     It fixed some things, it broke some things.  Pretty much standard
>     fare for anyone who has ever done work on the vm_map lock, including
>     yours truely.  John Dyson couldn't get it right, David Greenman couldn't
>     get it right, I couldn't get it completely right... getting it to do 
>     the right thing even under -stable is difficult, which is why I am
>     suggesting that it simply be made into an exclusive lock in -current.

In addition to the fact it doesn't actually serialize the general 
modification of the vm_map {} structure itself, just certain kinds of 
changes, so is easily a primary reason that the VM system as it stands now 
is inherently single-threaded.

-- 
Brian Fundakowski Feldman                           \'[ FreeBSD ]''''''''''\
  <> green@FreeBSD.org  <> bfeldman@tislabs.com      \  The Power to Serve! \
 Opinions expressed are my own.                       \,,,,,,,,,,,,,,,,,,,,,,\



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