Date: Fri, 13 May 2011 22:05:34 +0300 From: Andriy Gapon <avg@FreeBSD.org> To: Max Laier <max@love2party.net> Cc: freebsd-current@FreeBSD.org Subject: Re: proposed smp_rendezvous change Message-ID: <4DCD80FE.3070608@FreeBSD.org> In-Reply-To: <201105131313.11677.max@love2party.net> References: <4DCD357D.6000109@FreeBSD.org> <4DCD4E21.7020800@FreeBSD.org> <201105131150.57548.max@love2party.net> <201105131313.11677.max@love2party.net>
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on 13/05/2011 20:13 Max Laier said the following: > Disregard this ... I misread the diff. You are indeed using [2] correctly as > the "all-clear" semaphore. I still believe, that it is safer/cleaner to do > this spin before releasing the lock instead (see my patch). Maybe. I consider my approach a minor optimization - that is, I think that normally smp_rendezvous calls would be sparse enough to never require that synchronization (as proved by the past experience). So synchroning/delaying the master CPU at the end of smp_rendezvous would slightly hurt performance. Having the check at the start should trigger the synchronization only when it is really required. -- Andriy Gapon
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