From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mailman by lists.gnu.org with tmda-scanned (Exim 4.43) id 1Dndua-0006P6-V6 for qemu-devel@nongnu.org; Wed, 29 Jun 2005 10:51:37 -0400 Received: from exim by lists.gnu.org with spam-scanned (Exim 4.43) id 1DnduW-0006Mk-9M for qemu-devel@nongnu.org; Wed, 29 Jun 2005 10:51:33 -0400 Received: from [199.232.76.173] (helo=monty-python.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1DnduV-0006Lw-RM for qemu-devel@nongnu.org; Wed, 29 Jun 2005 10:51:31 -0400 Received: from [64.233.162.199] (helo=zproxy.gmail.com) by monty-python.gnu.org with esmtp (Exim 4.34) id 1DndwK-0007WR-Ql for qemu-devel@nongnu.org; Wed, 29 Jun 2005 10:53:24 -0400 Received: by zproxy.gmail.com with SMTP id s18so137891nze for ; Wed, 29 Jun 2005 07:48:34 -0700 (PDT) Message-ID: Date: Wed, 29 Jun 2005 16:48:32 +0200 From: Alexander Toresson Subject: Re: [Qemu-devel] Timing problems In-Reply-To: <42C2A042.4050304@gmx.de> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable Content-Disposition: inline References: <42C2A042.4050304@gmx.de> Reply-To: Alexander Toresson , qemu-devel@nongnu.org List-Id: qemu-devel.nongnu.org List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Oliver Gerlich wrote: > Alexander Toresson wrote: > > I'm running windows 2000 in qemu 0.7.0 with kqemu 0.6.2-1 on i386 > > debian linux. First thing I tried to do was to run a benchmark program > > (qemu w/o kqemu vs qemu w/ kqemu). I got strange results, and I also > > noted that timing didn't seem to be that good, so I re-tried to run > > the benchmark program, but with the date & clock settings window in > > the background. This is the result: The more cpu that is used in the > > virtual cpu, the faster time flies by. For example, when it's nearly > > idle, time is too slow. If it goes from idle to 100% cpu-use, time > > flies by at 5x the speed it should. This is true both when I use kqemu > > and when I don't. This cpu is capable of speedstep, but I have > > disabled it while doing this test. I think I would get even more weird > > results if I enabled it. > > This makes it impossible to run a benchmark and get any useful results > > out of it. Also, trying to run a game on qemu would be a disaster. >=20 > Not necessarily, Age of Empires 2 runs quite well under Qemu + Win98SE > (on an Athlon 2600+, host: Debian Linux, kernel 2.6.9). > > > However, running normal programs aren't any problem. Except that I > > have to be very quick when changing resolution in w2k (it should wait > > 15s, now time flies away and those 15 becomes 2s :)). > > > > Before compiling qemu 0.7.0 with kqemu 0.6.2-1, I ran qemu > > 0.6.something, taken from the debian testing repository, and it had > > the same problem. > > > > Regards, Alexander Toresson > > > > PS. I'm susprised nobody has seen this problem before. Is it just me > > who experience it? >=20 > Although I use Visual Studio 5 and Age of Empires 2 inside Qemu (with > Win98SE and Win2k), I never noticed such problems, and the Windows clock > always seemed quite right (and VC++ stresses the CPU quite a lot!). But > admittedly I never ran benchmarks or had a closer look at the guest > system time. >=20 Well, it happens any time I stress the cpu. Having the clock settings window open and then double-clicking on My Documents is enough to see the clock accelerate and then go back to normal speed. malc wrote: >CPU frequency scaling might be the cause. If your OS uses speedstep >or similar tech QEMU timers will misbehave. This was tested when speedstep was disabled, which I did by shutting down powernowd. Then cat /proc/cpuinfo shows 1.86ghz constantly, which is the maximum cpu frequency. Regards, Alexander Toresson