From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from sc8-sf-mx1-b.sourceforge.net ([10.3.1.91] helo=mail.sourceforge.net) by sc8-sf-list1-new.sourceforge.net with esmtp (Exim 4.43) id 1IzEZu-0004GU-Bm for user-mode-linux-devel@lists.sourceforge.net; Mon, 03 Dec 2007 08:55:30 -0800 Received: from mx1.redhat.com ([66.187.233.31]) by mail.sourceforge.net with esmtp (Exim 4.44) id 1IzEZu-0005WV-0S for user-mode-linux-devel@lists.sourceforge.net; Mon, 03 Dec 2007 08:55:30 -0800 References: From: Jeff Moyer Date: Mon, 03 Dec 2007 11:55:16 -0500 In-Reply-To: (Miklos Szeredi's message of "Mon\, 03 Dec 2007 16\:32\:51 +0100") Message-ID: MIME-Version: 1.0 Subject: Re: [uml-devel] [2.6.24 BUG] 100% iowait on host while UML is running List-Id: The user-mode Linux development list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: user-mode-linux-devel-bounces@lists.sourceforge.net Errors-To: user-mode-linux-devel-bounces@lists.sourceforge.net To: Miklos Szeredi Cc: user-mode-linux-devel@lists.sourceforge.net, jdike@addtoit.com, linux-kernel@vger.kernel.org, zach.brown@oracle.com, torvalds@linux-foundation.org, akpm@linux-foundation.org Miklos Szeredi writes: > On 2.6.24, top started showing 100% iowait on one CPU when a UML > instance was running (but completely idle). I've traced it to this > commit [1]. Reverting it cures the problem. Hi, The UML code sits in io_getevents waiting for an event to be submitted and completed. This is a case I completely overlooked when putting together the referenced patch. We could check ctx->reqs_active before scheduling to determine whether or not we are waiting for I/O, but this would require taking the context lock in order to be accurate. Given that the test would be only for the sake of book keeping, it might be okay to do it outside of the lock. Zach, what are your thoughts on this? -Jeff [1] commit 41d10da3717409de33d5441f2f6d8f072ab3fbb6 ------------------------------------------------------------------------- SF.Net email is sponsored by: The Future of Linux Business White Paper from Novell. From the desktop to the data center, Linux is going mainstream. Let it simplify your IT future. http://altfarm.mediaplex.com/ad/ck/8857-50307-18918-4 _______________________________________________ User-mode-linux-devel mailing list User-mode-linux-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/user-mode-linux-devel