Date: Tue, 25 Aug 1998 19:08:18 +0100 (BST) From: Doug Rabson <dfr@nlsystems.com> To: Garrett Wollman <wollman@khavrinen.lcs.mit.edu> Cc: "John S. Dyson" <dyson@iquest.net>, current@FreeBSD.ORG Subject: Re: Serious bug in vm_page.h in current Message-ID: <Pine.BSF.4.01.9808251907120.17263-100000@herring.nlsystems.com> In-Reply-To: <199808251441.KAA02038@khavrinen.lcs.mit.edu>
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On Tue, 25 Aug 1998, Garrett Wollman wrote: > <<On Tue, 25 Aug 1998 10:11:36 +0100 (BST), Doug Rabson <dfr@nlsystems.com> said: > > > On Tue, 25 Aug 1998, John S. Dyson wrote: > > >> PAGE_BWAKEUP would decr busy, and wakeup if PG_WANTED > >> and busy == 0. > >> > >> PAGE_WAKEUP would clear PG_BUSY, and wakeup if PG_WANTED. > >> > >> Each of the above would ignore the other condition. There will > >> be extra wakeups, but those won't significantly affect performance. > > > I don't understand this part of the code of the code very well. It > > doesn't seem to me that a few extra wakeups is a problem. Not waking up > > at all is a problem... > > This sounds very much like it could be related to the lockup Matt > Dillon and I have been seeing. I just rebooted newsswitch with this > change in it; I should know by the end of the day whether it had > any effect. I think that John's patch as posted will not work at all due to a misunderstanding. It will probably just cause hangs since vm_page::busy will be decremented but never incremented. -- Doug Rabson Mail: dfr@nlsystems.com Nonlinear Systems Ltd. Phone: +44 181 951 1891 Fax: +44 181 381 1039 To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-current" in the body of the message
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