Date: Mon, 1 Nov 2004 02:51:13 -0800 From: Alfred Perlstein <alfred@freebsd.org> To: Alan Cox <alc@cs.rice.edu> Cc: cvs-all@FreeBSD.org Subject: Re: cvs commit: src/sys/vm vm_zeroidle.c Message-ID: <20041101105113.GS24892@elvis.mu.org> In-Reply-To: <20041101045331.GP16728@cs.rice.edu> References: <200410311932.i9VJWvmo058193@repoman.freebsd.org> <20041101031317.GK24892@elvis.mu.org> <20041101045331.GP16728@cs.rice.edu>
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* Alan Cox <alc@cs.rice.edu> [041031 20:53] wrote: > On Sun, Oct 31, 2004 at 07:13:17PM -0800, Alfred Perlstein wrote: > > * Alan Cox <alc@FreeBSD.org> [041031 11:33] wrote: > > > alc 2004-10-31 19:32:57 UTC > > > > > > FreeBSD src repository > > > > > > Modified files: > > > sys/vm vm_zeroidle.c > > > Log: > > > Introduce a Boolean variable wakeup_needed to avoid repeated, unnecessary > > > calls to wakeup() by vm_page_zero_idle_wakeup(). > > > > > > Revision Changes Path > > > 1.31 +9 -2 src/sys/vm/vm_zeroidle.c > > > > Why not switch to a cv? > > Calling cv_signal repeatedly would be no better than calling wakeup() > repeatedly. Either way, a Boolean variable is desirable to prevent > unnecessary calls. Yah, I figured there would be something in the cv code to optimize the "no waiters" case. > As for the question of msleep()/wakeup() vs. cv_wait*()/cv_signal(), > cv_wait*() has no analogue to msleep()'s PDROP. In this case, there > is no need to hold the lock after returning from the sleep. So, > msleep(PDROP) is better suited to this case. Didn't see that. thank you, -Alfred
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