Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759213AbXK1Pfj (ORCPT ); Wed, 28 Nov 2007 10:35:39 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752478AbXK1Pfb (ORCPT ); Wed, 28 Nov 2007 10:35:31 -0500 Received: from fxip-0047f.externet.hu ([88.209.222.127]:44800 "EHLO dorka.pomaz.szeredi.hu" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751719AbXK1Pf3 (ORCPT ); Wed, 28 Nov 2007 10:35:29 -0500 To: jdike@addtoit.com CC: mingo@elte.hu, user-mode-linux-devel@lists.sourceforge.net, linux-kernel@vger.kernel.org In-reply-to: <20071128150637.GA5518@c2.user-mode-linux.org> (message from Jeff Dike on Wed, 28 Nov 2007 10:06:37 -0500) Subject: Re: -rt doesn't compile for UML References: <20071128150637.GA5518@c2.user-mode-linux.org> Message-Id: From: Miklos Szeredi Date: Wed, 28 Nov 2007 16:35:12 +0100 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 921 Lines: 26 > > When writing a big file to a ubd disk, everything in uml slows down to > > a crawl, even though CPU usage is minimal. > > What exactly is your test case? Something like: dd if=/host/tmp/bigfile of=/tmp/bigfile bs=1048576 count=100 and run 'top' or 'watch something' in another terminal, which sometimes completely stops updating during the write. > I have some patches which theoretically should help I/O performance > which I've been sitting on because I can't find a case where they > help. It's not I/O performance I'm worried about, but scheduling latencies. CPU use inside and outside the UML is minimal, so I can't see where this slowdown comes from. Miklos - 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/