From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:51080) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1cksNi-0007NW-JZ for qemu-devel@nongnu.org; Mon, 06 Mar 2017 08:08:55 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1cksNf-0002rG-FW for qemu-devel@nongnu.org; Mon, 06 Mar 2017 08:08:54 -0500 Received: from mail-wr0-x22b.google.com ([2a00:1450:400c:c0c::22b]:33406) by eggs.gnu.org with esmtps (TLS1.0:RSA_AES_128_CBC_SHA1:16) (Exim 4.71) (envelope-from ) id 1cksNf-0002r0-8i for qemu-devel@nongnu.org; Mon, 06 Mar 2017 08:08:51 -0500 Received: by mail-wr0-x22b.google.com with SMTP id u48so116150596wrc.0 for ; Mon, 06 Mar 2017 05:08:51 -0800 (PST) References: From: Alex =?utf-8?Q?Benn=C3=A9e?= In-reply-to: Date: Mon, 06 Mar 2017 13:08:56 +0000 Message-ID: <87lgsiimc7.fsf@linaro.org> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit Subject: Re: [Qemu-devel] -rtc clock=vm with -icount 1, sleep=off introduces unexpected delays in device interactions List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: =?utf-8?B?RnLDqWTDqXJpYw==?= Konrad Cc: "Nutaro, James J." , "'qemu-devel@nongnu.org'" , Paolo Bonzini Frédéric Konrad writes: > Hi Jim, > > I think Alex and Paolo worked on an mttcg/icount issue. > Not sure if its related or not. If you are running a tree post-MTTCG merge you will need to add Paolo's patches: Subject: [PATCH 0/6] tcg: fix icount super slowdown Date: Fri, 3 Mar 2017 14:11:08 +0100 Message-Id: <20170303131113.25898-1-pbonzini@redhat.com> > > Fred > > On 03/03/2017 08:38 PM, Nutaro, James J. wrote: >> My original problem seems to stem from something that changed in the way that device emulation and instruction execution interact (I'm guessing). To reproduce the issue, I started a linux image with >> >> qemu-system-i386 -rtc clock=vm -monitor none -icount 1,sleep=off jack.img >> >> After booting, I run >> >> ping localhost >> >> The first round trip time reports look reasonable, being in the millisecond to sub-millisecond range. These occur while the emulator is running slower than real time. >> >> After a bit, the emulator speeds up (skipping over idle periods during I/O?) and the round trip times jump to hundreds of milliseconds, which I had not expected. >> >> If you want to try this experiment yourself, you can get the disk image that I used from here: >> >> http://www.ornl.gov/~1qn/qemu-images/jack.img >> >> >> Jim >> -- Alex Bennée