From owner-freebsd-current Tue May 28 23:37:25 2002 Delivered-To: freebsd-current@freebsd.org Received: from scaup.mail.pas.earthlink.net (scaup.mail.pas.earthlink.net [207.217.120.49]) by hub.freebsd.org (Postfix) with ESMTP id D165537B404 for ; Tue, 28 May 2002 23:37:18 -0700 (PDT) Received: from pool0116.cvx21-bradley.dialup.earthlink.net ([209.179.192.116] helo=mindspring.com) by scaup.prod.itd.earthlink.net with esmtp (Exim 3.33 #2) id 17Cx50-0003f3-00; Tue, 28 May 2002 23:37:06 -0700 Message-ID: <3CF476E7.D465D5C3@mindspring.com> Date: Tue, 28 May 2002 23:36:23 -0700 From: Terry Lambert X-Mailer: Mozilla 4.7 [en]C-CCK-MCD {Sony} (Win98; U) X-Accept-Language: en MIME-Version: 1.0 To: Poul-Henning Kamp Cc: Peter Wemm , Richard Wenninger , current@FreeBSD.org Subject: Re: UMA lock References: <10399.1022653079@critter.freebsd.dk> Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Sender: owner-freebsd-current@FreeBSD.ORG Precedence: bulk List-ID: List-Archive: (Web Archive) List-Help: (List Instructions) List-Subscribe: List-Unsubscribe: X-Loop: FreeBSD.ORG Poul-Henning Kamp wrote: > In message <20020529061540.88CD6380A@overcee.wemm.org>, Peter Wemm writes: > >As you said, _sleeping_ is the problem. M_WAITOK means "you may sleep if > >you like". ie: it is a time bomb waiting for the right low memory condition > >which will then explode with a 100% authentic crash or lock up. > > > >Pretend it said M_SLEEPOK instead of M_WAITOK. > > Uhm, I'm actually seeing the opposite behaviour as well: after I > changed the md(4) driver to use M_NOWAIT I still see malloc/zalloc > sleeping... I'm with Poul on this one, Peter: M_WAITOK doesn't mean what you think it means: it's doesn't mean tsleep may be called, and M_NOWAIT doesn't mean tsleep() _won't_ be called, in practice. It's either incredibly badly named, or it's incredibly badly implemented -- I would argue the latter, actually, since even if it's completely orthogonal, you're screwed because it means you have two call conversion systems, without a WITNESS intersection to detect deadly embraces. 8-(. -- Terry To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-current" in the body of the message