From owner-freebsd-realtime@FreeBSD.ORG Thu Nov 11 18:14:49 2004 Return-Path: Delivered-To: freebsd-realtime@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id C45B616A4CE for ; Thu, 11 Nov 2004 18:14:49 +0000 (GMT) Received: from web41215.mail.yahoo.com (web41215.mail.yahoo.com [66.218.93.48]) by mx1.FreeBSD.org (Postfix) with SMTP id 866F343D31 for ; Thu, 11 Nov 2004 18:14:49 +0000 (GMT) (envelope-from arne_woerner@yahoo.com) Received: (qmail 64691 invoked by uid 60001); 11 Nov 2004 18:14:49 -0000 Comment: DomainKeys? See http://antispam.yahoo.com/domainkeys DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=s1024; d=yahoo.com; b=qsCFSgkVvXbJCx+pFWOvQRL1MKfbPjGA8a6oLX8RvMGh9hGrQ+BYWORWx0nWxGO4EpJ7TPkpIkeC8tOQ38wTElluyDuxqkwkDxibo3raAJwhWa2lf0LYYK9u2+m73WEpLFw9DmkQCIYpQRFWjAiTeBKpSTOhscr8k8nNt2SiYyw= ; Message-ID: <20041111181446.64684.qmail@web41215.mail.yahoo.com> Received: from [83.129.243.160] by web41215.mail.yahoo.com via HTTP; Thu, 11 Nov 2004 10:14:46 PST Date: Thu, 11 Nov 2004 10:14:46 -0800 (PST) From: Arne "Wörner" To: freebsd-realtime@freebsd.org MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Subject: system calls X-BeenThere: freebsd-realtime@freebsd.org X-Mailman-Version: 2.1.1 Precedence: list List-Id: Realtime extensions per POSIX 1003.4 List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 11 Nov 2004 18:14:49 -0000 Hiho! I just read in the BUGS section of the man page of rtprio(1), that system calls are never preemted. Does that mean, that a "read(fd,buffer,10000000)" blocks all other processes, until 10^7 bytes are read even if fd points to a file on a very slow and huge floppy disc? Does that mean, that no process can run, after the kernel ordered a hard disc to move its heads until the data is transfer from disc to memory (sometimes it feels like :) )? Unfortunately I am quite sure, that I would not find out the truth by experimentation or by looking at source code. Sorry... If at least one answer is "yes", then I think, that it would be much better for the performance, if processes could run, while the kernel manages lengthy io-ops (I still remember, that there was a picture about 4 process states: running, waiting, dead, blocked; and while the blocked processes are blocking, the waiting processes are competiting for the CPU/-s). Thanks. Bye Arne __________________________________ Do you Yahoo!? Check out the new Yahoo! Front Page. www.yahoo.com