From mboxrd@z Thu Jan 1 00:00:00 1970 From: "David S. Ahern" Subject: Re: performance with guests running 2.4 kernels (specifically RHEL3) Date: Wed, 30 Apr 2008 08:23:23 -0600 Message-ID: <481880DB.90308@cisco.com> References: <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> <20080430135611.GL15421@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Cc: kvm-devel , Marcelo Tosatti To: "Daniel P. Berrange" , Avi Kivity Return-path: In-Reply-To: <20080430135611.GL15421@redhat.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 Yes, the 4G/4G patch and the 64G options are both enabled for the hugemem kernel: CONFIG_HIGHMEM64G=y CONFIG_X86_4G=y Differences between the "standard" kernel and the hugemem kernel: # diff config-2.4.21-47.ELsmp config-2.4.21-47.ELhugemem 2157,2158c2157,2158 < CONFIG_M686=y < # CONFIG_MPENTIUMIII is not set --- > # CONFIG_M686 is not set > CONFIG_MPENTIUMIII=y 2169c2169 < CONFIG_X86_PGE=y --- > # CONFIG_X86_PGE is not set 2193c2193 < # CONFIG_X86_4G is not set --- > CONFIG_X86_4G=y 2365,2366c2365 < CONFIG_M686=y < CONFIG_X86_PGE=y --- > CONFIG_MPENTIUMIII=y 2369,2372d2367 < # CONFIG_MXT is not set < CONFIG_HOTPLUG_PCI=y < CONFIG_HOTPLUG_PCI_COMPAQ=m < CONFIG_HOTPLUG_PCI_IBM=m 2373a2369 > CONFIG_X86_4G=y 2377,2379d2372 < # CONFIG_EWRK3 is not set < CONFIG_UNIX98_PTY_COUNT=2048 < CONFIG_HZ=512 2382a2376,2383 > # CONFIG_MXT is not set > CONFIG_HOTPLUG_PCI=y > CONFIG_HOTPLUG_PCI_COMPAQ=m > CONFIG_HOTPLUG_PCI_IBM=m > # CONFIG_EWRK3 is not set > CONFIG_UNIX98_PTY_COUNT=2048 > CONFIG_DEBUG_BUGVERBOSE=y > # CONFIG_PNPBIOS is not set Avi: Centos releases: http://isoredirect.centos.org/centos/3/isos/i386/ I am running RHEL3.8 which I do not see listed. Also, I'll need to work on a stock install and try to capture some kind of workload that exhibits the problem. It will be a couple of days. david Daniel P. Berrange wrote: > On Wed, Apr 30, 2008 at 07:39:53AM -0600, David S. Ahern wrote: >> Avi Kivity wrote: >>> David S. Ahern wrote: >>>> Another tidbit for you guys as I make my way through various >>>> permutations: >>>> I installed the RHEL3 hugemem kernel and the guest behavior is *much* >>>> better. >>>> System time still has some regular hiccups that are higher than xen >>>> and esx >>>> (e.g., 1 minute samples out of 5 show system time between 10 and 15%), >>>> but >>>> overall guest behavior is good with the hugemem kernel. >>>> >>>> >>> Wait, the amount of info here is overwhelming. Let's stick with the >>> current kernel (32-bit, HIGHMEM4G, right?) >>> >>> Did you get any traces with bypass_guest_pf=0? That may show more info. >>> >> My preference is to stick with the "standard", 32-bit RHEL3 kernel in the guest. >> My point in the last email was that the hugemem kernel shows a remarkable >> difference (it uses 3-levels of page tables right?). I was hoping that would >> ring a bell with someone. > > IIRC, the RHEL-3 hugemem kernel is using the 4g/4g split patches which > give userspace and kernelspace their own independant pagetables > > http://lwn.net/Articles/39925/ > http://lwn.net/Articles/39283/ > > Dan. ------------------------------------------------------------------------- This SF.net email is sponsored by the 2008 JavaOne(SM) Conference Don't miss this year's exciting event. There's still time to save $100. Use priority code J8TL2D2. http://ad.doubleclick.net/clk;198757673;13503038;p?http://java.sun.com/javaone