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From: "Manfred Spraul" <manfred@colorfullife.com>
To: "Andrea Arcangeli" <andrea@suse.de>, "David Howells" <dhowells@redhat.com>
Cc: "Linus Torvalds" <torvalds@transmeta.com>, <Ulrich.Weigand@de.ibm.com>,
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In-Reply-To: <torvalds@transmeta.com> <5079.1000911203@warthog.cambridge.redhat.com> <20010919200357.Z720@athlon.random>
Subject: Re: Deadlock on the mm->mmap_sem
Date: Wed, 19 Sep 2001 20:19:09 +0200
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> if we go generic then I strongly recommend my version of the generic
> semaphores is _much_ faster (and cleaner) than this one (it even
allows
> more than 2^31 concurrent readers on 64 bit archs ;).
>
Andrea,

implementing recursive semaphores is trivial, but do you have any idea
how to fix the latency problem?
Multithreaded, iobound apps that use mmap are unusable with unfair
semaphores.

My test app hangs for minutes within mprotect().

--
    Manfred