Date: Wed, 9 Jun 2004 19:29:18 +0000 From: Bosko Milekic <bmilekic@FreeBSD.org> To: src-committers@FreeBSD.org, cvs-src@FreeBSD.org, cvs-all@FreeBSD.org Subject: Re: cvs commit: src/sys/vm uma_core.c Message-ID: <20040609192918.GA44607@freefall.freebsd.org>
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Please note: this only fixes the cluster case and not other types
of ext bufs which do MEXTADD. Basically the refcounting method
works well as long as the refcounts are type-stable. This could
be made a requirement for all ext_bufs without problem, and for
those who do not provide ref cnts, I will replace the malloc() of
the refcnt with a uma zone allocation of the refcnt from a special
UMA_ZONE_NOFREE refcnt zone.
We need to use atomics here because there is no place where to put
a mutex, so I can't fix this by just protecting the refcnt with
a mutex.
-Bosko
bmilekic 2004-06-09 19:18:51 UTC
FreeBSD src repository
Modified files:
sys/vm uma_core.c
Log:
Make the slabrefzone, the zone from which we allocated slabs with
internal reference counters, UMA_ZONE_NOFREE. This way, those slabs
(with their ref counts) will be effectively type-stable, then using
a trick like this on the refcount is no longer dangerous:
...
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