From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from sc8-sf-mx1-b.sourceforge.net ([10.3.1.11] helo=sc8-sf-mx1.sourceforge.net) by sc8-sf-list1.sourceforge.net with esmtp (Exim 4.30) id 1BsS7Y-0005sn-W2 for user-mode-linux-devel@lists.sourceforge.net; Wed, 04 Aug 2004 13:12:20 -0700 Received: from zsc3s004.nortelnetworks.com ([47.81.138.65]) by sc8-sf-mx1.sourceforge.net with esmtp (Exim 4.34) id 1BsS7Y-0002m9-NB for user-mode-linux-devel@lists.sourceforge.net; Wed, 04 Aug 2004 13:12:20 -0700 Received: from zsc3c028.us.nortel.com (zsc3c028.us.nortel.com [47.81.138.28]) by zsc3s004.nortelnetworks.com (Switch-2.2.6/Switch-2.2.0) with ESMTP id i74KC8m14328 for ; Wed, 4 Aug 2004 13:12:08 -0700 (PDT) Message-ID: <411142B4.7000603@nortelnetworks.com> From: Joe Marzot MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Subject: [uml-devel] Q: UML thread communication - scheduling oddness Sender: user-mode-linux-devel-admin@lists.sourceforge.net Errors-To: user-mode-linux-devel-admin@lists.sourceforge.net List-Unsubscribe: , List-Id: The user-mode Linux development list List-Post: List-Help: List-Subscribe: , List-Archive: Date: Wed, 04 Aug 2004 16:10:28 -0400 To: user-mode-linux-devel@lists.sourceforge.net Cc: Randy Macleod We are seeing some sub-optimal behaviour (at least for our use) for communication between several UMLs. It appears the responsiveness of a given UML to application level network messaging is a function of how busy the serverside UML is. That is, if I run a little busy loop /mnt/plankton/stress --cpu 1 --io 1 on the server side, the round trip time for messages is greatly *improved*. without this activity and a basically dormant server side UML the round trip times show considerable variabilty with gaps on the order of seconds. Now for the question: Can some one explain the event mechanism and communication pathways for network packets(using tuntap networking) delivered to the UML kernel and then for the kernel to a userspace process? It looks like the kernel thread is responsive enough because if we do simple pings they don't suffer from the huge gaps as the user based pings do. I would like to understand how the kernel thread wakes up to grab the packets from the tap device and then how it notifies the user space thread to deal with it...ultimately maybe there is something we can do to make the userspace thread have less latency (other than running my dummy busy thing from above of course). thanks for any help in understanding. regards, Giovanni ps. We are using 2.4.2x with 2.4.24-1 patch in skas mode ------------------------------------------------------- This SF.Net email is sponsored by OSTG. Have you noticed the changes on Linux.com, ITManagersJournal and NewsForge in the past few weeks? Now, one more big change to announce. We are now OSTG- Open Source Technology Group. Come see the changes on the new OSTG site. www.ostg.com _______________________________________________ User-mode-linux-devel mailing list User-mode-linux-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/user-mode-linux-devel