Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261876AbTELDNf (ORCPT ); Sun, 11 May 2003 23:13:35 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S261878AbTELDNf (ORCPT ); Sun, 11 May 2003 23:13:35 -0400 Received: from zcars04e.nortelnetworks.com ([47.129.242.56]:41437 "EHLO zcars04e.nortelnetworks.com") by vger.kernel.org with ESMTP id S261876AbTELDNe (ORCPT ); Sun, 11 May 2003 23:13:34 -0400 Message-ID: <3EBF144E.7050608@nortelnetworks.com> Date: Sun, 11 May 2003 23:26:06 -0400 X-Sybari-Space: 00000000 00000000 00000000 From: Chris Friesen User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:0.9.8) Gecko/20020204 X-Accept-Language: en-us MIME-Version: 1.0 To: Muli Ben-Yehuda Cc: Linux Kernel Mailing List Subject: Re: [RFC] new syscall to allow notification when arbitrary pids die References: <3EBC9C62.5010507@nortelnetworks.com> <20030510073842.GA31003@actcom.co.il> Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1629 Lines: 41 Muli Ben-Yehuda wrote: > On Sat, May 10, 2003 at 02:29:54AM -0400, Chris Friesen wrote: > > >>I see two immediate uses for this. One would be to enable a "watcher" >>process which can do useful things on the death of processes which >>registered with it (logging, respawning, notifying other processes, >>etc). >> > > Do it from user space, kill(pid, 0), check for ESRCH. I might see the > benefit of a new system call if it was synchronous (wait() semantics), > but since signal delivery is asynch anyway.... Exactly. I don't want to explicitly poll each process being monitored to see if it is still alive. That solution doesn't scale well--what happens when you are monitoring 5000 processes and you want to make sure that you catch them within a certain amount of time? You end up spending a lot of cpu time doing the monitoring. > There's already a well established way to do what you want (get > non-immediate notification of process death). What benefit would your > approach give? Its cheaper and faster. It only costs a single call for each process, and then you get notified immediately when it dies. Chris -- Chris Friesen | MailStop: 043/33/F10 Nortel Networks | work: (613) 765-0557 3500 Carling Avenue | fax: (613) 765-2986 Nepean, ON K2H 8E9 Canada | email: cfriesen@nortelnetworks.com - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/