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Date:      Wed, 06 Jun 2001 16:24:20 -0700 (PDT)
From:      John Baldwin <jhb@FreeBSD.org>
To:        Alfred Perlstein <alfred@FreeBSD.org>
Cc:        obrien@FreeBSD.org, Freebsd-alpha@FreeBSD.org, Andrew Gallatin <gallatin@cs.duke.edu>
Subject:   Re: -current kernel still considered dangerous
Message-ID:  <XFMail.010606162420.jhb@FreeBSD.org>
In-Reply-To: <20010606184523.P1832@superconductor.rush.net>

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On 06-Jun-01 Alfred Perlstein wrote:
> * John Baldwin <jhb@FreeBSD.org> [010606 12:58] wrote:
>> 
>> > Is there any documentation what the locking requirements of various
>> > vm functions are now? I tested osf1 after my initial set of commits to
>> > catch
>> > alpha up to x86, but an assert must have been added since then.
>> 
>> Not really, and it is in a state of flux right now.  On my todo list is to
>> change the vm_map's to be locked by a sx lock, and once that is done I will
>> change those mtx_assert's to simply require the sx lock rather than the
>> vm_mtx
>> lock.  However, I'm still not sure how vm_page's will be locked. 
>> vm_object's
>> will probably have their own mutex or sx lock though.
> 
> Linux uses a single lock to protect them, most of the splvm()'s that you
> removed were placeholders for the vm page queue's mutex.

Which use a single lock: pages, objects, or both?  Due to the fact that
getpages/putpages can block, I'm thinking that objects may actually need a sx
lock.

-- 

John Baldwin <jhb@FreeBSD.org> -- http://www.FreeBSD.org/~jhb/
PGP Key: http://www.baldwin.cx/~john/pgpkey.asc
"Power Users Use the Power to Serve!"  -  http://www.FreeBSD.org/

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