Date: Tue, 23 Nov 2010 15:26:55 +0200 From: Andriy Gapon <avg@freebsd.org> To: freebsd-hackers@freebsd.org, "Robert N. M. Watson" <rwatson@freebsd.org> Subject: Re: dtrace/cyclic deadlock Message-ID: <4CEBC11F.9000402@freebsd.org> In-Reply-To: <4CEB6039.2040700@freebsd.org> References: <4CEB6039.2040700@freebsd.org>
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on 23/11/2010 08:33 Andriy Gapon said the following: > I think that this is quite similar to what we do for per-CPU caches in UMA and > so the same approach should work here. > That is, as in (Open)Solaris, the data should be accessed only from the owning > CPU and spinlock_enter()/spinlock_exit() should be used to prevent races between > non-interrupt code and nested interrupt code. Here's a patch that makes our version of cyclic.c a little bit closer to the upstream version whilst implementing the above idea: http://people.freebsd.org/~avg/cyclic-deadlock.diff All accesses to per-CPU cyclics data are performed strictly from the corresponding CPUs in an interrupt or interrupt-like context. "Upcalls" occur in event timer's interrupt filter and all down calls are performed via smp_rendezvous_cpus(). I will appreciate reviews and testing. Thanks! -- Andriy Gapon
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