From owner-freebsd-hackers Fri Jan 23 04:57:32 1998 Return-Path: Received: (from majordom@localhost) by hub.freebsd.org (8.8.8/8.8.8) id EAA28385 for hackers-outgoing; Fri, 23 Jan 1998 04:57:32 -0800 (PST) (envelope-from owner-freebsd-hackers@FreeBSD.ORG) Received: from word.smith.net.au (ppp11.portal.net.au [202.12.71.111]) by hub.freebsd.org (8.8.8/8.8.8) with ESMTP id EAA28377 for ; Fri, 23 Jan 1998 04:57:28 -0800 (PST) (envelope-from mike@word.smith.net.au) Received: from word (localhost [127.0.0.1]) by word.smith.net.au (8.8.8/8.8.5) with ESMTP id XAA00630; Fri, 23 Jan 1998 23:19:36 +1030 (CST) Message-Id: <199801231249.XAA00630@word.smith.net.au> X-Mailer: exmh version 2.0zeta 7/24/97 To: Luigi Rizzo cc: daniel_sobral@voga.com.br, hackers@FreeBSD.ORG Subject: Re: uiomove() In-reply-to: Your message of "Fri, 23 Jan 1998 11:47:42 BST." <199801231047.LAA02217@labinfo.iet.unipi.it> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Date: Fri, 23 Jan 1998 23:19:35 +1030 From: Mike Smith Sender: owner-freebsd-hackers@FreeBSD.ORG Precedence: bulk > > Yeah (well, kind of yeah), but... What about SMP? What about a process in > > one processor calling read() while a process in another processor calls > > write()? > > not sure, but I think in our SMP implementation only one process > can be in the kernel at each time, isn't it ? Too much of the > existing code assumes that, and it would have been impossible to > fix everything to have SMP running. This is no longer true. The SMP people started with a single "monster lock" as you describe. This is the traditional starting point, as it reduces the amount of work required to begin with. >From there, there have been several rounds of lock "push downs", where parts of the kernel are made SMP-aware. At this point in time, drivers are still below a single lock, and are likely to remain there for some time. 8) -- \\ Sometimes you're ahead, \\ Mike Smith \\ sometimes you're behind. \\ mike@smith.net.au \\ The race is long, and in the \\ msmith@freebsd.org \\ end it's only with yourself. \\