From mboxrd@z Thu Jan 1 00:00:00 1970 From: Avi Kivity Subject: Re: performance with guests running 2.4 kernels (specifically RHEL3) Date: Tue, 13 May 2008 10:25:38 +0300 Message-ID: <48294272.5020801@qumranet.com> References: <48054518.3000104@cisco.com> <4805BCF1.6040605@qumranet.com> <4807BD53.6020304@cisco.com> <48085485.3090205@qumranet.com> <480C188F.3020101@cisco.com> <480C5C39.4040300@qumranet.com> <480E492B.3060500@cisco.com> <480EEDA0.3080209@qumranet.com> <480F546C.2030608@cisco.com> <481215DE.3000302@cisco.com> <20080428181550.GA3965@dmt> <4816617F.3080403@cisco.com> <4817F30C.6050308@cisco.com> <48184228.2020701@qumranet.com> <481876A9.1010806@cisco.com> <48187903.2070409@qumranet.com> <4826E744.1080107@qumranet.com> <4826F668.6030305@qumranet.com> <48290FC2.4070505@cisco.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Cc: kvm-devel To: "David S. Ahern" Return-path: In-Reply-To: <48290FC2.4070505@cisco.com> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: kvm-devel-bounces@lists.sourceforge.net Errors-To: kvm-devel-bounces@lists.sourceforge.net List-Id: kvm.vger.kernel.org David S. Ahern wrote: > That does the trick with kscand. > > Not so fast... the patch updates the flood count to 5. Can you check if a lower value still works? Also, whether updating the flood count to 5 (without the rest of the patch) works? Unconditionally bumping the flood count to 5 will likely cause a performance regression on other guests. While I was able to see excessive flooding, I couldn't reproduce your kscand problem. Running /bin/true always returned immediately for me. > Do you have recommendations for clock source settings? For example in my > test case for this patch the guest gained 73 seconds (ahead of real > time) after only 3 hours, 5 min of uptime. > The kernel is trying to correlate tsc and pit, which isn't going to work. Try disabling the tsc, set edx.bit4=0 for cpuid.eax=1 in qemu-kvm-x86 .c do_cpuid_ent(). -- error compiling committee.c: too many arguments to function ------------------------------------------------------------------------- This SF.net email is sponsored by: Microsoft Defy all challenges. Microsoft(R) Visual Studio 2008. http://clk.atdmt.com/MRT/go/vse0120000070mrt/direct/01/