Date: Fri, 5 Dec 2008 23:46:00 +0100 From: Roman Divacky <rdivacky@FreeBSD.org> To: Konstantin Belousov <kib@FreeBSD.org> Cc: svn-src-head@FreeBSD.org, svn-src-all@FreeBSD.org, src-committers@FreeBSD.org Subject: Re: svn commit: r185647 - in head/sys: kern sys Message-ID: <20081205224600.GA16948@freebsd.org> In-Reply-To: <200812052050.mB5KoOcV072648@svn.freebsd.org> References: <200812052050.mB5KoOcV072648@svn.freebsd.org>
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On Fri, Dec 05, 2008 at 08:50:24PM +0000, Konstantin Belousov wrote: > Author: kib > Date: Fri Dec 5 20:50:24 2008 > New Revision: 185647 > URL: http://svn.freebsd.org/changeset/base/185647 > > Log: > Several threads in a process may do vfork() simultaneously. Then, all > parent threads sleep on the parent' struct proc until corresponding > child releases the vmspace. Each sleep is interlocked with proc mutex of > the child, that triggers assertion in the sleepq_add(). The assertion > requires that at any time, all simultaneous sleepers for the channel use > the same interlock. > > Silent the assertion by using conditional variable allocated in the > child. Broadcast the variable event on exec() and exit(). > > Since struct proc * sleep wait channel is overloaded for several > unrelated events, I was unable to remove wakeups from the places where > cv_broadcast() is added, except exec(). are there any differences (performance etc.) in using condition variables instead of sleep/wakeup?
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