From owner-freebsd-hackers Fri Dec 11 07:35:36 1998 Return-Path: Received: (from majordom@localhost) by hub.freebsd.org (8.8.8/8.8.8) id HAA19270 for freebsd-hackers-outgoing; Fri, 11 Dec 1998 07:35:36 -0800 (PST) (envelope-from owner-freebsd-hackers@FreeBSD.ORG) Received: from ns.tar.com (ns.tar.com [204.95.187.2]) by hub.freebsd.org (8.8.8/8.8.8) with ESMTP id HAA19255 for ; Fri, 11 Dec 1998 07:35:32 -0800 (PST) (envelope-from lists@tar.com) Received: from ppro.tar.com (ppro.tar.com [204.95.187.9]) by ns.tar.com (8.9.1/8.9.1) with SMTP id JAA59487; Fri, 11 Dec 1998 09:35:15 -0600 (CST) (envelope-from lists@tar.com) Message-Id: <199812111535.JAA59487@ns.tar.com> From: "Richard Seaman, Jr." To: "Marc Slemko" Cc: "hackers@freebsd.org" Date: Fri, 11 Dec 98 09:35:15 -0600 Reply-To: "Richard Seaman, Jr." X-Mailer: PMMail 1.92 For OS/2 MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Subject: Re: pread/pwrite Sender: owner-freebsd-hackers@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.ORG On Fri, 11 Dec 98 09:19:06 -0600, Richard Seaman, Jr. wrote: >In the uniprocessor case, it is my understanding that the kernel >is nonpreemtive. Thus, if pread/pwrite are syscalls, no locking >is needed any more than it is needed for read/write. A follow-up clarification. The implementation of read/write and pread/pwrite in sys_generic.c all call an underlying device specific read/write. There is synchronization needed in most cases to handle interrupts, but this is done within the device specific read/write. To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message