From owner-freebsd-hackers Wed Feb 17 20:33:48 1999 Delivered-To: freebsd-hackers@freebsd.org Received: from rover.village.org (rover.village.org [204.144.255.49]) by hub.freebsd.org (Postfix) with SMTP id 0DD1911323 for ; Wed, 17 Feb 1999 20:33:33 -0800 (PST) (envelope-from imp@village.org) Received: from harmony [10.0.0.6] by rover.village.org with esmtp (Exim 1.71 #1) id 10DL9Y-0007VE-00; Wed, 17 Feb 1999 21:33:32 -0700 Received: from harmony.village.org (localhost.village.org [127.0.0.1]) by harmony.village.org (8.9.2/8.8.3) with ESMTP id VAA64812; Wed, 17 Feb 1999 21:36:22 -0700 (MST) Message-Id: <199902180436.VAA64812@harmony.village.org> To: Matthew Dillon Subject: Re: portability of shm, mmap, pipes and socket IPC Cc: hackers@FreeBSD.ORG In-reply-to: Your message of "Wed, 10 Feb 1999 01:07:44 PST." <199902100907.BAA79553@apollo.backplane.com> References: <199902100907.BAA79553@apollo.backplane.com> <199902092246.PAA10658@usr02.primenet.com> <199902100403.MAA55849@spinner.netplex.com.au> <19990210085847.A11710@gil.physik.rwth-aachen.de> Date: Wed, 17 Feb 1999 21:36:22 -0700 From: Warner Losh Sender: owner-freebsd-hackers@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.ORG In message <199902100907.BAA79553@apollo.backplane.com> Matthew Dillon writes: : The problem is that linux updates the timeval structure on return, : telling you how much time is left. Linux is the only system to do this. And it was flawed because if there is an interrupt that causes a higher priority process to run, the value is too small. The value is only an approximation. : Many programs assumed that tv was const... i.e. not modified by : the call, and so would initialize the structure once then use it : multiple times. It was before Linux. : I don't know what linux does now, but most programs these days : reinitialize tv on each select() call in order to work around : any potential problem. Linux's system call still modifies things. However, there is a bsd_select in most libraries that does the right thing, at least the thing that all other oses do. Warner To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message