Re: [CentOS-virt] performance differences between kvm/xen
Hi Grant, On Wed, Oct 27, 2010 at 11:00 AM, Grant McWilliams grantmasterfl...@gmail.com wrote: Todd, I think there's more than one way to look at this as well. As Xen becomes more of a product and less of an installable package it will probably have to be profiled as a product. The XCP devs hope that XCP will eventually be available via a package install (for example something similar to yum install xcp). Say benchmark XCP on particular hardware and benchmark RHEL KVM on the same hardware and ESX as well. It makes sense to benchmark a XEN kernel and a KVM kernel if we have that flexibility but that's starting to shrink. Another test that I don't think is THAT important anymore is tesing Xen with and without pvops kernels. There were some rumors going around that the old 2.6.18 kernel was faster than the new pvops. I was going to put together tests and never got to it. Not that it makes any difference in the future because the old kernel is fast going away. Yeah the old one is going away, comparing the forward port kernel (for example from OpenSUSE) to the new pv_ops one is what we will want to do. The pv_ops one may be better or worse under certain loads, but unless we test, how will we know? Once we can demonstrate it, the pv_ops kernel can be improved as needed too. What I'd like to have is a standardized test with a way of multiple people uploading it and comparing results so we can run it on as many systems as possible. Data correlation could then be done on the data. Currently we have one test over here and another over there and the tests never seem to be updated or even run again to verify results. Maybe none of it matters as the hypervisor becomes inconsequential. Great, yes that is what research at Clarkson University tried to do. As far as I know no one at Clarkson is actively working on it though. I will check with them when I get a chance though. I'm going to look at the tests you've done as soon as time permits. What we completed were some basic things. There is still more to test. Thanks, Todd -- Todd Deshane http://todddeshane.net http://runningxen.com ___ CentOS-virt mailing list CentOS-virt@centos.org http://lists.centos.org/mailman/listinfo/centos-virt
Re: [CentOS-virt] performance differences between kvm/xen
On Oct 25, 2010, at 8:14 AM, Todd Deshane wrote: I was also going to mention that we should look at scalability and performance isolation. Some references and previous studies here: http://todddeshane.net/research/Xen_versus_KVM_20080623.pdf http://clarkson.edu/~jnm/publications/isolation_ExpCS_FINALSUBMISSION.pdf http://clarkson.edu/~jnm/publications/freenix04-clark.pdf I only got as far as the top one. One concern: the nestled comment We believe that KVM may have performed better than Xen in terms of I/O due to disk caching makes me skeptical of the value of the results if this wasn't taken into consideration (in other words I think it is a much bigger problem than the aforementioned comment gives credit to, such that it ought to be at least addressed in the concluding remarks) ... for instance if my VM load-outs use all but ~384M of total memory (that being the amount I leave to the host, most of it used) then there's not going to be much extra RAM for memory cache/buffers with on the host side (depending greatly on what vm.swappiness camp you are in). Based on the author's result output [1] (since the VM parameters aren't given in the paper), as relates to a disk-intensive test they in effect gave 2G potential caching to Xen but ~4G to KVM. Based at least on the amount of free memory on my Xen/KVM hosts I don't think this host memor y cache bias can be assumed to be a bonus trait that would normally be present for KVM. (And of course a cache bias would be even more noticeable in the 256MB Phoronix test and in the 4x128M isolation tests [2] ...) [1] http://web2.clarkson.edu/projects/virtualization/benchvm/results/performance/ [2] http://web2.clarkson.edu/projects/virtualization/benchvm/results/isolation/xen/memory/specweb1/SPECweb_Support.20080614-100931.html BTW, I do realize you're pointing out that we should look at scalability and isolation, and here I am just giving critical feedback on a 3 year old paper ... yes you're right those are important! I just want to make sure the tests are fair ;-) Eric ___ CentOS-virt mailing list CentOS-virt@centos.org http://lists.centos.org/mailman/listinfo/centos-virt
Re: [CentOS-virt] performance differences between kvm/xen
On Tue, Oct 26, 2010 at 4:15 PM, Eric Searcy emsea...@gmail.com wrote: On Oct 25, 2010, at 8:14 AM, Todd Deshane wrote: I was also going to mention that we should look at scalability and performance isolation. Some references and previous studies here: http://todddeshane.net/research/Xen_versus_KVM_20080623.pdf http://clarkson.edu/~jnm/publications/isolation_ExpCS_FINALSUBMISSION.pdf http://clarkson.edu/~jnm/publications/freenix04-clark.pdf I only got as far as the top one. One concern: the nestled comment We believe that KVM may have performed better than Xen in terms of I/O due to disk caching makes me skeptical of the value of the results if this wasn't taken into consideration (in other words I think it is a much bigger problem than the aforementioned comment gives credit to, such that it ought to be at least addressed in the concluding remarks) ... for instance if my VM load-outs use all but ~384M of total memory (that being the amount I leave to the host, most of it used) then there's not going to be much extra RAM for memory cache/buffers with on the host side (depending greatly on what vm.swappiness camp you are in). Based on the author's result output [1] (since the VM parameters aren't given in the paper), as relates to a disk-intensive test they in effect gave 2G potential caching to Xen but ~4G to KVM. Based at least on the amount of free memory on my Xen/KVM hosts I don't think this host memor y cache bias can be assumed to be a bonus trait that would normally be present for KVM. (And of course a cache bias would be even more noticeable in the 256MB Phoronix test and in the 4x128M isolation tests [2] ...) [1] http://web2.clarkson.edu/projects/virtualization/benchvm/results/performance/ [2] http://web2.clarkson.edu/projects/virtualization/benchvm/results/isolation/xen/memory/specweb1/SPECweb_Support.20080614-100931.html BTW, I do realize you're pointing out that we should look at scalability and isolation, and here I am just giving critical feedback on a 3 year old paper ... yes you're right those are important! I just want to make sure the tests are fair ;-) These are old tests now and not necessarily perfect, but they were Xen and KVM on the same kernel. KVM very early on and not necessarily in its best light. The Xen dom0/domU kernel was also not the best light for Xen. The point was to try to compare them on the same kernel. Xen and KVM on the same kernel has happened in the form of OpenSUSE's forward port of the Xen dom0 kernel with KVM that is already in mainline. The pv_ops kernel is not fully mainline, but is getting close. Some distros now have Xen dom0 kernels based on the pv_ops kernel, which could also run KVM. In any case, some updated numbers would be very welcome. And yes, taking scalability, performance isolation, and other factors into account is important. I have been involved in quite a few performance studies over the years and I will try to give advice and help as I can. On Tue, Oct 26, 2010 at 2:38 PM, Grant McWilliams grantmasterfl...@gmail.com wrote: So you've already done a lot of this then Todd? Should we just be making a standardized test out of your work? At Clarkson, we tried to build a standardized tool called benchvm as a standard, but it has been stuck in an alpha state for awhile http://code.google.com/p/benchvm/ I can dig up the rejected academic paper on the benchvm if people are interested, feel free to email me privately. I wonder if using things like puppet, the phoronix test suite, etc. are a simpler way to go? I guess it all depends on how general a benchmarking tool is needed. Thanks, Todd -- Todd Deshane http://todddeshane.net http://runningxen.com ___ CentOS-virt mailing list CentOS-virt@centos.org http://lists.centos.org/mailman/listinfo/centos-virt
Re: [CentOS-virt] performance differences between kvm/xen
On Thu, Oct 21, 2010 at 3:56 PM, Grant McWilliams grantmasterfl...@gmail.com wrote: On Thu, Oct 21, 2010 at 12:50 PM, Grant McWilliams grantmasterfl...@gmail.com wrote: On Thu, Oct 21, 2010 at 3:29 AM, Karanbir Singh mail-li...@karan.org wrote: On 10/21/2010 12:01 AM, Grant McWilliams wrote: So what we're on the verge of doing here is creating a test set... I'd love to see a shell script that ran a bunch of tests, gathered data about the system and then created an archive that would then be uploaded to a website which created graphs. Dreaming maybe but it would be consistent. So what goes in our testset? I am trying to create just that - a kickstart that will build a machine as a Xen dom0, build 4 domU's, fire up puppet inside the domU's do the testing and scp results into a central git repo. Then something similar for KVM. will get the basic framework online today. - KB __ Do you suppose you could get it to use Phoronix Test Suite so we can start to have measurable stats? We could do the same thing for any VM software - even the ones that don't allow publishing stats in the EULA... I'm also wondering if we should do the whole test suite or a subset. Here is the list of tests.. One thing that I think probably needs to be modified for our needs is a Dom0 controller to run various tests in each DomU simultaneously then collate the date. Virtual worlds are more complex than non-virtual ones. Sometimes something runs great in on VM but drags when multiple VMs are being used. I was also going to mention that we should look at scalability and performance isolation. Some references and previous studies here: http://todddeshane.net/research/Xen_versus_KVM_20080623.pdf http://clarkson.edu/~jnm/publications/isolation_ExpCS_FINALSUBMISSION.pdf http://clarkson.edu/~jnm/publications/freenix04-clark.pdf Also, is there anybody that has access to or would be able to get access to run SPECvirt? http://www.spec.org/virt_sc2010/ Thanks, Todd -- Todd Deshane http://todddeshane.net http://runningxen.com ___ CentOS-virt mailing list CentOS-virt@centos.org http://lists.centos.org/mailman/listinfo/centos-virt
Re: [CentOS-virt] performance differences between kvm/xen
On Tue, Oct 19, 2010 at 12:47:03PM +0200, Dennis Jacobfeuerborn wrote: On 10/19/2010 09:41 AM, Pasi Kärkkäinen wrote: On Sat, Oct 16, 2010 at 09:58:15PM +0200, Dennis Jacobfeuerborn wrote: On 10/16/2010 08:11 PM, Pasi Kärkkäinen wrote: On Thu, Oct 14, 2010 at 02:16:42PM +0100, Bart Swedrowski wrote: Hi Karanbir, On 14 October 2010 19:59, Karanbir Singhmail-li...@karan.org wrote: On 10/14/2010 07:48 AM, Tom Bishop wrote: I think xen is still on top in terms of performance and featuresnow that is indeed what it 'feels' like, but I'm quite keen on putting some numbers on that. I have done some testing some time ago on one of the EQ machines that I got from hetzner.de. Full spec of the machine was as following: * Intel® Core??? i7-920 * 8 GB DDR3 RAM * 2 x 750 GB SATA-II HDD It's nothing big but even though results are quite interesting. All tests were performed on CentOS 5.5 x86_64 with PostgreSQL 8.4 (from CentOS repos). Note that 64bit Xen guests should be HVM, not PV, for best performance. Xen HVM guests obviously still need to have PV-on-HVM drivers installed. 32bit Xen guests can be PV. Hm, why would HVM be faster than PV for 64 bit guests? It's because of the x86_64 architecture, afaik. There was some good technical explananation about it, but I can't remember the url now. In that case I'll have to call this advice extremely bogus and you probably should refrain from passing it on. The only way I can see this being true is some weird corner case. It's not bogus, you can go ask on xen-devel :) -- Pasi ___ CentOS-virt mailing list CentOS-virt@centos.org http://lists.centos.org/mailman/listinfo/centos-virt
Re: [CentOS-virt] performance differences between kvm/xen
On 10/21/2010 12:01 AM, Grant McWilliams wrote: So what we're on the verge of doing here is creating a test set... I'd love to see a shell script that ran a bunch of tests, gathered data about the system and then created an archive that would then be uploaded to a website which created graphs. Dreaming maybe but it would be consistent. So what goes in our testset? I am trying to create just that - a kickstart that will build a machine as a Xen dom0, build 4 domU's, fire up puppet inside the domU's do the testing and scp results into a central git repo. Then something similar for KVM. will get the basic framework online today. - KB ___ CentOS-virt mailing list CentOS-virt@centos.org http://lists.centos.org/mailman/listinfo/centos-virt
Re: [CentOS-virt] performance differences between kvm/xen
On Thu, Oct 21, 2010 at 3:29 AM, Karanbir Singh mail-li...@karan.orgwrote: On 10/21/2010 12:01 AM, Grant McWilliams wrote: So what we're on the verge of doing here is creating a test set... I'd love to see a shell script that ran a bunch of tests, gathered data about the system and then created an archive that would then be uploaded to a website which created graphs. Dreaming maybe but it would be consistent. So what goes in our testset? I am trying to create just that - a kickstart that will build a machine as a Xen dom0, build 4 domU's, fire up puppet inside the domU's do the testing and scp results into a central git repo. Then something similar for KVM. will get the basic framework online today. - KB __ Do you suppose you could get it to use Phoronix Test Suite so we can start to have measurable stats? We could do the same thing for any VM software - even the ones that don't allow publishing stats in the EULA... I'm also wondering if we should do the whole test suite or a subset. Here is the list of tests.. aio-stress apache battery-power-usage blogbench bork build-apache build-imagemagick build-linux-kernel build-mplayer build-mysql build-php bullet bwfirt byte c-ray cachebench compilebench compliance-acpi compliance-sensors compress-7zip compress-gzip compress-lzma compress-pbzip2 crafty dbench dcraw doom3 encode-ape encode-flac encode-mp3 encode-ogg encode-wavpack espeak et etqw-demo-iqc etqw-demo etqw ffmpeg fhourstones fio fs-mark gcrypt geekbench gluxmark gmpbench gnupg graphics-magick gtkperf hdparm-read himeno hmmer idle-power-usage idle iozone j2dbench java-scimark2 jgfxbat john-the-ripper juliagpu jxrendermark lightsmark mafft mandelbulbgpu mandelgpu mencoder minion mrbayes n-queens nero2d network-loopback nexuiz-iqc nexuiz npb openarena openssl opstone-svd opstone-svsp opstone-vsp padman pgbench phpbench postmark povray prey pybench pyopencl qgears2 quake4 ramspeed render-bench scimark2 smallpt-gpu smallpt smokin-guns specviewperf10 specviewperf9 sqlite stream stresscpu2 sudokut sunflow supertuxkart systester tachyon tiobench tremulous trislam tscp ttsiod-renderer unigine-heaven unigine-sanctuary unigine-tropics unpack-linux urbanterror ut2004-demo vdrift-fps-monitor vdrift video-cpu-usage video-extensions warsow wine-cloth wine-domino wine-fire2 wine-hdr wine-metaballs wine-vf2 wine-water x11perf x264 xplane9-iqc xplane9 yafray Grant McWilliams . ___ CentOS-virt mailing list CentOS-virt@centos.org http://lists.centos.org/mailman/listinfo/centos-virt
Re: [CentOS-virt] performance differences between kvm/xen
On Thu, Oct 21, 2010 at 12:50 PM, Grant McWilliams grantmasterfl...@gmail.com wrote: On Thu, Oct 21, 2010 at 3:29 AM, Karanbir Singh mail-li...@karan.orgwrote: On 10/21/2010 12:01 AM, Grant McWilliams wrote: So what we're on the verge of doing here is creating a test set... I'd love to see a shell script that ran a bunch of tests, gathered data about the system and then created an archive that would then be uploaded to a website which created graphs. Dreaming maybe but it would be consistent. So what goes in our testset? I am trying to create just that - a kickstart that will build a machine as a Xen dom0, build 4 domU's, fire up puppet inside the domU's do the testing and scp results into a central git repo. Then something similar for KVM. will get the basic framework online today. - KB __ Do you suppose you could get it to use Phoronix Test Suite so we can start to have measurable stats? We could do the same thing for any VM software - even the ones that don't allow publishing stats in the EULA... I'm also wondering if we should do the whole test suite or a subset. Here is the list of tests.. One thing that I think probably needs to be modified for our needs is a Dom0 controller to run various tests in each DomU simultaneously then collate the date. Virtual worlds are more complex than non-virtual ones. Sometimes something runs great in on VM but drags when multiple VMs are being used. Grant McWilliams ___ CentOS-virt mailing list CentOS-virt@centos.org http://lists.centos.org/mailman/listinfo/centos-virt
Re: [CentOS-virt] performance differences between kvm/xen
If I understand that paper correctly, HVM+VT-d outperforms PV by quite a lot (if you have VT-d support on your system). Thanks for that link. Just to make my criticism of the initial claim more clear: I don't claim that HVM can never be faster than PV but that you need to understand when exactly this is the case. For example I'm not sure that x86_64 vs. x86 really enters into this but I can definitely see VT-d making an impact there. Regards, Dennis Even though this is Intel talking I'd still be very sceptical of getting those numbers since this is quite the opposite of what I've seen. Maybe the vt-d is getting good enough to actually accelerate IO operations but even so that would only happen on the latest hardware. I will say that Xen has a really long packet path though. Grant McWilliams ___ CentOS-virt mailing list CentOS-virt@centos.org http://lists.centos.org/mailman/listinfo/centos-virt
Re: [CentOS-virt] performance differences between kvm/xen
On 10/20/2010 08:12 AM, Grant McWilliams wrote: If I understand that paper correctly, HVM+VT-d outperforms PV by quite a lot (if you have VT-d support on your system). Thanks for that link. Just to make my criticism of the initial claim more clear: I don't claim that HVM can never be faster than PV but that you need to understand when exactly this is the case. For example I'm not sure that x86_64 vs. x86 really enters into this but I can definitely see VT-d making an impact there. Regards, Dennis Even though this is Intel talking I'd still be very sceptical of getting those numbers since this is quite the opposite of what I've seen. Maybe the vt-d is getting good enough to actually accelerate IO operations but even so that would only happen on the latest hardware. I will say that Xen has a really long packet path though. Being skeptical is the best approach in the absence of verifiable/falsifiable data. Today or tomorrow I'll get my hands on a new host system and although it is supposed to go into production immediately I will probably find some time to do some rudimentary benchmarking in that regard to see if this is worth investigating further. Right now I'm planning to use fio for block device measurements but don't know any decent (and uncomplicated) network i/o benchmarking tools. Any ideas what tools I could use to quickly get some useful data on this from the machine? Regards, Dennis ___ CentOS-virt mailing list CentOS-virt@centos.org http://lists.centos.org/mailman/listinfo/centos-virt
Re: [CentOS-virt] performance differences between kvm/xen
On 10/20/2010 12:35 PM, Dennis Jacobfeuerborn wrote: Being skeptical is the best approach in the absence of verifiable/falsifiable data. Today or tomorrow I'll get my hands on a new host system and although it is supposed to go into production immediately I will probably find some time to do some rudimentary benchmarking in that regard to see if this is worth investigating further. Right now I'm That sounds great. I've got a machine coming online in the next few days as well and will do some testing on there. Its got 2 of these : Intel(R) Xeon(R) CPU E5310 So not the newest/greatest, but should be fairly representative. planning to use fio for block device measurements but don't know any decent (and uncomplicated) network i/o benchmarking tools. Any ideas what tools I could use to quickly get some useful data on this from the machine? iozone and openssl speed tests are always a good thing to run as a 'warm up' to your app level testing. Since pgtest has been posted here already, I'd say that is definitely one thing to include so it creates a level of common-code-testing and comparison. mysql-bench is worth hitting as well. I have a personal interest in web app delivery, so a apache-bench hosted from an external machine hitting domU's / VM's ( but more than 1 instance, and hitting more than 1 VM / domU at the same time ) would be good to have as well. And yes, publish lots of machine details and also details on the code / platform / versions used. I will try to do the same ( but will limit my testing to whats already available in the distro ) thanks - KB ___ CentOS-virt mailing list CentOS-virt@centos.org http://lists.centos.org/mailman/listinfo/centos-virt
Re: [CentOS-virt] performance differences between kvm/xen
Ok so I'd like to help, since most folks have Intel Chipsets, I have a AMD 4p(16 core)/32gig memory opteron server that I'm running that we can get some numbers onbut it would be nice if we could run apples to apples...I have iozone loaded and can run that but would be nice to run using the same parametersis there any way we could list the types of test we would like to run and the actual command with options listed and then we would have some thing to compare at least level the playing field...KB, any thoughts, is this a good idea? On Wed, Oct 20, 2010 at 6:52 AM, Karanbir Singh mail-li...@karan.orgwrote: On 10/20/2010 12:35 PM, Dennis Jacobfeuerborn wrote: Being skeptical is the best approach in the absence of verifiable/falsifiable data. Today or tomorrow I'll get my hands on a new host system and although it is supposed to go into production immediately I will probably find some time to do some rudimentary benchmarking in that regard to see if this is worth investigating further. Right now I'm That sounds great. I've got a machine coming online in the next few days as well and will do some testing on there. Its got 2 of these : Intel(R) Xeon(R) CPU E5310 So not the newest/greatest, but should be fairly representative. planning to use fio for block device measurements but don't know any decent (and uncomplicated) network i/o benchmarking tools. Any ideas what tools I could use to quickly get some useful data on this from the machine? iozone and openssl speed tests are always a good thing to run as a 'warm up' to your app level testing. Since pgtest has been posted here already, I'd say that is definitely one thing to include so it creates a level of common-code-testing and comparison. mysql-bench is worth hitting as well. I have a personal interest in web app delivery, so a apache-bench hosted from an external machine hitting domU's / VM's ( but more than 1 instance, and hitting more than 1 VM / domU at the same time ) would be good to have as well. And yes, publish lots of machine details and also details on the code / platform / versions used. I will try to do the same ( but will limit my testing to whats already available in the distro ) thanks - KB ___ CentOS-virt mailing list CentOS-virt@centos.org http://lists.centos.org/mailman/listinfo/centos-virt ___ CentOS-virt mailing list CentOS-virt@centos.org http://lists.centos.org/mailman/listinfo/centos-virt
Re: [CentOS-virt] performance differences between kvm/xen
On Wed, Oct 20, 2010 at 6:24 AM, Tom Bishop bisho...@gmail.com wrote: Ok so I'd like to help, since most folks have Intel Chipsets, I have a AMD 4p(16 core)/32gig memory opteron server that I'm running that we can get some numbers onbut it would be nice if we could run apples to apples...I have iozone loaded and can run that but would be nice to run using the same parametersis there any way we could list the types of test we would like to run and the actual command with options listed and then we would have some thing to compare at least level the playing field...KB, any thoughts, is this a good idea? On Wed, Oct 20, 2010 at 6:52 AM, Karanbir Singh mail-li...@karan.orgwrote: On 10/20/2010 12:35 PM, Dennis Jacobfeuerborn wrote: Being skeptical is the best approach in the absence of verifiable/falsifiable data. Today or tomorrow I'll get my hands on a new host system and although it is supposed to go into production immediately I will probably find some time to do some rudimentary benchmarking in that regard to see if this is worth investigating further. Right now I'm That sounds great. I've got a machine coming online in the next few days as well and will do some testing on there. Its got 2 of these : Intel(R) Xeon(R) CPU E5310 So not the newest/greatest, but should be fairly representative. planning to use fio for block device measurements but don't know any decent (and uncomplicated) network i/o benchmarking tools. Any ideas what tools I could use to quickly get some useful data on this from the machine? iozone and openssl speed tests are always a good thing to run as a 'warm up' to your app level testing. Since pgtest has been posted here already, I'd say that is definitely one thing to include so it creates a level of common-code-testing and comparison. mysql-bench is worth hitting as well. I have a personal interest in web app delivery, so a apache-bench hosted from an external machine hitting domU's / VM's ( but more than 1 instance, and hitting more than 1 VM / domU at the same time ) would be good to have as well. And yes, publish lots of machine details and also details on the code / platform / versions used. I will try to do the same ( but will limit my testing to whats already available in the distro ) thanks - KB __ So what we're on the verge of doing here is creating a test set... I'd love to see a shell script that ran a bunch of tests, gathered data about the system and then created an archive that would then be uploaded to a website which created graphs. Dreaming maybe but it would be consistent. So what goes in our testset? Just a generic list, add to or take away form it.. - phoronix test suite ? - iozone - kernbench - dbench - bonnie++ - iperf - nbench The phoronix test suite has most tests in it in addition to many many others. Maybe a subset of those tests with the aim of testing Virtualization would be good? Grant McWilliams ___ CentOS-virt mailing list CentOS-virt@centos.org http://lists.centos.org/mailman/listinfo/centos-virt
Re: [CentOS-virt] performance differences between kvm/xen
On Sat, Oct 16, 2010 at 09:58:15PM +0200, Dennis Jacobfeuerborn wrote: On 10/16/2010 08:11 PM, Pasi Kärkkäinen wrote: On Thu, Oct 14, 2010 at 02:16:42PM +0100, Bart Swedrowski wrote: Hi Karanbir, On 14 October 2010 19:59, Karanbir Singhmail-li...@karan.org wrote: On 10/14/2010 07:48 AM, Tom Bishop wrote: I think xen is still on top in terms of performance and featuresnow that is indeed what it 'feels' like, but I'm quite keen on putting some numbers on that. I have done some testing some time ago on one of the EQ machines that I got from hetzner.de. Full spec of the machine was as following: * Intel® Core??? i7-920 * 8 GB DDR3 RAM * 2 x 750 GB SATA-II HDD It's nothing big but even though results are quite interesting. All tests were performed on CentOS 5.5 x86_64 with PostgreSQL 8.4 (from CentOS repos). Note that 64bit Xen guests should be HVM, not PV, for best performance. Xen HVM guests obviously still need to have PV-on-HVM drivers installed. 32bit Xen guests can be PV. Hm, why would HVM be faster than PV for 64 bit guests? It's because of the x86_64 architecture, afaik. There was some good technical explananation about it, but I can't remember the url now. -- Pasi ___ CentOS-virt mailing list CentOS-virt@centos.org http://lists.centos.org/mailman/listinfo/centos-virt
Re: [CentOS-virt] performance differences between kvm/xen
On 10/19/2010 09:41 AM, Pasi Kärkkäinen wrote: On Sat, Oct 16, 2010 at 09:58:15PM +0200, Dennis Jacobfeuerborn wrote: On 10/16/2010 08:11 PM, Pasi Kärkkäinen wrote: On Thu, Oct 14, 2010 at 02:16:42PM +0100, Bart Swedrowski wrote: Hi Karanbir, On 14 October 2010 19:59, Karanbir Singhmail-li...@karan.org wrote: On 10/14/2010 07:48 AM, Tom Bishop wrote: I think xen is still on top in terms of performance and featuresnow that is indeed what it 'feels' like, but I'm quite keen on putting some numbers on that. I have done some testing some time ago on one of the EQ machines that I got from hetzner.de. Full spec of the machine was as following: * Intel® Core??? i7-920 * 8 GB DDR3 RAM * 2 x 750 GB SATA-II HDD It's nothing big but even though results are quite interesting. All tests were performed on CentOS 5.5 x86_64 with PostgreSQL 8.4 (from CentOS repos). Note that 64bit Xen guests should be HVM, not PV, for best performance. Xen HVM guests obviously still need to have PV-on-HVM drivers installed. 32bit Xen guests can be PV. Hm, why would HVM be faster than PV for 64 bit guests? It's because of the x86_64 architecture, afaik. There was some good technical explananation about it, but I can't remember the url now. In that case I'll have to call this advice extremely bogus and you probably should refrain from passing it on. The only way I can see this being true is some weird corner case. Regards, Dennis ___ CentOS-virt mailing list CentOS-virt@centos.org http://lists.centos.org/mailman/listinfo/centos-virt
Re: [CentOS-virt] performance differences between kvm/xen
On 10/19/2010 01:16 PM, Jerry Franz wrote: On 10/19/2010 03:47 AM, Dennis Jacobfeuerborn wrote: On 10/19/2010 09:41 AM, Pasi Kärkkäinen wrote: It's because of the x86_64 architecture, afaik. There was some good technical explananation about it, but I can't remember the url now. In that case I'll have to call this advice extremely bogus and you probably should refrain from passing it on. The only way I can see this being true is some weird corner case. There appear to be some interactions with the Intel VT-d processor features. http://www.xen.org/files/xensummit_intel09/xensummit2009_IOVirtPerf.pdf If I understand that paper correctly, HVM+VT-d outperforms PV by quite a lot (if you have VT-d support on your system). Thanks for that link. Just to make my criticism of the initial claim more clear: I don't claim that HVM can never be faster than PV but that you need to understand when exactly this is the case. For example I'm not sure that x86_64 vs. x86 really enters into this but I can definitely see VT-d making an impact there. Regards, Dennis ___ CentOS-virt mailing list CentOS-virt@centos.org http://lists.centos.org/mailman/listinfo/centos-virt
Re: [CentOS-virt] performance differences between kvm/xen
On Sat, Oct 16, 2010 at 12:58 PM, Dennis Jacobfeuerborn denni...@conversis.de wrote: On 10/16/2010 08:11 PM, Pasi Kärkkäinen wrote: On Thu, Oct 14, 2010 at 02:16:42PM +0100, Bart Swedrowski wrote: Hi Karanbir, On 14 October 2010 19:59, Karanbir Singhmail-li...@karan.org wrote: On 10/14/2010 07:48 AM, Tom Bishop wrote: I think xen is still on top in terms of performance and featuresnow that is indeed what it 'feels' like, but I'm quite keen on putting some numbers on that. I have done some testing some time ago on one of the EQ machines that I got from hetzner.de. Full spec of the machine was as following: Note that 64bit Xen guests should be HVM, not PV, for best performance. Xen HVM guests obviously still need to have PV-on-HVM drivers installed. 32bit Xen guests can be PV. Hm, why would HVM be faster than PV for 64 bit guests? Regards, Dennis lol, there's seems to be a lot of hearsay surrounding performance and Xen. Grant McWilliams Some people, when confronted with a problem, think I know, I'll use Windows. Now they have two problems. ___ CentOS-virt mailing list CentOS-virt@centos.org http://lists.centos.org/mailman/listinfo/centos-virt
Re: [CentOS-virt] performance differences between kvm/xen
On Thu, Oct 14, 2010 at 02:16:42PM +0100, Bart Swedrowski wrote: Hi Karanbir, On 14 October 2010 19:59, Karanbir Singh mail-li...@karan.org wrote: On 10/14/2010 07:48 AM, Tom Bishop wrote: I think xen is still on top in terms of performance and featuresnow that is indeed what it 'feels' like, but I'm quite keen on putting some numbers on that. I have done some testing some time ago on one of the EQ machines that I got from hetzner.de. Full spec of the machine was as following: * Intel® Core??? i7-920 * 8 GB DDR3 RAM * 2 x 750 GB SATA-II HDD It's nothing big but even though results are quite interesting. All tests were performed on CentOS 5.5 x86_64 with PostgreSQL 8.4 (from CentOS repos). Note that 64bit Xen guests should be HVM, not PV, for best performance. Xen HVM guests obviously still need to have PV-on-HVM drivers installed. 32bit Xen guests can be PV. -- Pasi I have run some PostgreSQL PGBench tests as well as Bonnie++ tests. The PostgreSQL tests was divided into two tests having three goes (to get an idea of average). The commands I used for testing were: dropdb pgbench sync sleep 3 createdb pgbench sync sleep 3 pgbench -i -s 100 -U postgres -d pgbench sync sleep 3 pgbench -c 10 -t 5000 -s 100 -U postgres -d pgbench 2/dev/null sync \ sleep 3 pgbench -c 10 -t 5000 -s 100 -U postgres -d pgbench 2/dev/null \ sync sleep 3 pgbench -c 10 -t 5000 -s 100 -U postgres -d pgbench 2/dev/null \ sync sleep 3 Now results. First CentOS5/x86_64 without any virtualisation, without any PostgreSQL optimisation: -bash-3.2$ pgbench -c 10 -t 5000 -s 100 -U postgres -d pgbench 2/dev/null pghost: pgport: nclients: 10 nxacts: 5000 dbName: pgbench transaction type: TPC-B (sort of) scaling factor: 100 number of clients: 10 number of transactions per client: 5000 number of transactions actually processed: 5/5 tps = 141.191292 (including connections establishing) tps = 141.196776 (excluding connections establishing) -bash-3.2$ pgbench -c 10 -t 5000 -s 100 -U postgres -d pgbench 2/dev/null pghost: pgport: nclients: 10 nxacts: 5000 dbName: pgbench transaction type: TPC-B (sort of) scaling factor: 100 number of clients: 10 number of transactions per client: 5000 number of transactions actually processed: 5/5 tps = 156.479561 (including connections establishing) tps = 156.486222 (excluding connections establishing) -bash-3.2$ pgbench -c 10 -t 5000 -s 100 -U postgres -d pgbench 2/dev/null pghost: pgport: nclients: 10 nxacts: 5000 dbName: pgbench transaction type: TPC-B (sort of) scaling factor: 100 number of clients: 10 number of transactions per client: 5000 number of transactions actually processed: 5/5 tps = 164.880109 (including connections establishing) tps = 164.888009 (excluding connections establishing) Now after optimisation (shared_buffers, effective_cache_size etc.): pghost: pgport: nclients: 10 nxacts: 5000 dbName: pgbench transaction type: TPC-B (sort of) scaling factor: 100 number of clients: 10 number of transactions per client: 5000 number of transactions actually processed: 5/5 tps = 403.430951 (including connections establishing) tps = 403.474562 (excluding connections establishing) pghost: pgport: nclients: 10 nxacts: 5000 dbName: pgbench transaction type: TPC-B (sort of) scaling factor: 100 number of clients: 10 number of transactions per client: 5000 number of transactions actually processed: 5/5 tps = 336.060764 (including connections establishing) tps = 336.093214 (excluding connections establishing) pghost: pgport: nclients: 10 nxacts: 5000 dbName: pgbench transaction type: TPC-B (sort of) scaling factor: 100 number of clients: 10 number of transactions per client: 5000 number of transactions actually processed: 5/5 tps = 446.607705 (including connections establishing) tps = 446.664466 (excluding connections establishing) Now KVM based VM with 7GB RAM and 8 CPUs. Using virtio and LVM partitions as backend. PostgreSQL results *w/o* optimisation. -bash-3.2$ pgbench -c 10 -t 5000 -s 100 -U postgres -d pgbench 2/dev/null sync sleep 3 pgbench -c 10 -t 5000 -s 100 -U postgres -d pgbench 2/dev/null sync sleep 3 pgbench -c 10 -t 5000 -s 100 -U postgres -d pgbench 2/dev/null sync sleep 3 pghost: pgport: nclients: 10 nxacts: 5000 dbName: pgbench transaction type: TPC-B (sort of) scaling factor: 100 number of clients: 10 number of transactions per client: 5000 number of transactions actually processed: 5/5 tps = 124.578488 (including connections establishing) tps = 124.585776 (excluding connections establishing) pghost: pgport: nclients: 10 nxacts: 5000 dbName: pgbench transaction type: TPC-B (sort of) scaling factor: 100 number of clients: 10 number of transactions per client: 5000 number of transactions actually processed: 5/5 tps = 140.451736 (including
Re: [CentOS-virt] performance differences between kvm/xen
On 10/16/2010 08:11 PM, Pasi Kärkkäinen wrote: On Thu, Oct 14, 2010 at 02:16:42PM +0100, Bart Swedrowski wrote: Hi Karanbir, On 14 October 2010 19:59, Karanbir Singhmail-li...@karan.org wrote: On 10/14/2010 07:48 AM, Tom Bishop wrote: I think xen is still on top in terms of performance and featuresnow that is indeed what it 'feels' like, but I'm quite keen on putting some numbers on that. I have done some testing some time ago on one of the EQ machines that I got from hetzner.de. Full spec of the machine was as following: * Intel® Core??? i7-920 * 8 GB DDR3 RAM * 2 x 750 GB SATA-II HDD It's nothing big but even though results are quite interesting. All tests were performed on CentOS 5.5 x86_64 with PostgreSQL 8.4 (from CentOS repos). Note that 64bit Xen guests should be HVM, not PV, for best performance. Xen HVM guests obviously still need to have PV-on-HVM drivers installed. 32bit Xen guests can be PV. Hm, why would HVM be faster than PV for 64 bit guests? Regards, Dennis ___ CentOS-virt mailing list CentOS-virt@centos.org http://lists.centos.org/mailman/listinfo/centos-virt
Re: [CentOS-virt] performance differences between kvm/xen
On 10/15/2010 02:00 PM, John L. Magee wrote: One thing to possibly consider with PostgreSQL performance especially, is that when using KVM VMs for some applications, PostgreSQL could be run native. This is a viable approach with KVM that could never work with Xen. Can you expand on this a little bit please ? - KB ___ CentOS-virt mailing list CentOS-virt@centos.org http://lists.centos.org/mailman/listinfo/centos-virt
Re: [CentOS-virt] performance differences between kvm/xen
I think he's right. Run PostgreSQL on the centos host directly, rather than from within a guest. The vm guests could access the database over the virtual lan, so speed of access for guests on the same server wouldn't be an issue. There are lots of ways of file sharing for example. You can share from within a linux or windows guest, or you could share directly from the centos host with samba or iSCSI. I get native speeds from guests, but I think running directly from the server is always going to be faster. ___ CentOS-virt mailing list CentOS-virt@centos.org http://lists.centos.org/mailman/listinfo/centos-virt
Re: [CentOS-virt] performance differences between kvm/xen
On 10/15/2010 10:56 PM, compdoc wrote: I think he's right. Run PostgreSQL on the centos host directly, rather than from within a guest. The vm guests could access the database over the virtual lan, so speed of access for guests on the same server wouldn't be an issue. I don't understand why that would have an issue with Xen, quite a lot of hosting companies run mysql on the dom0's and let all the VM's hosted on the box access it over a socket. - KB ___ CentOS-virt mailing list CentOS-virt@centos.org http://lists.centos.org/mailman/listinfo/centos-virt
Re: [CentOS-virt] performance differences between kvm/xen
I don't have any benchmarks per se just my recent testing of them I think xen is still on top in terms of performance and featuresnow having said that my experience in the past with kvm and my latest testing with 5.5 and KVM I can say that KVM has made great strides with the virtio drivers for the disk and nic, my latest vm's that I am using with those drivers are very snappy and so far I am very pleased.I'm a big redhat fan and think that KVM will only continue to get better and I believe at some point will equal or pass xenI'm waiting for rhel6 to see what they are going to be rolling out...I have not had any time to play with the beta or look at fedora On Thu, Oct 14, 2010 at 11:32 AM, Karanbir Singh mail-li...@karan.orgwrote: hi guys, Just wondering if anyone has done any performance testing between kvm and xen on CentOS-5 ( using centos as host and vm in every case ) ? Regards, -- Karanbir Singh London, UK | http://www.karan.org/ | twitter.com/kbsingh ICQ: 2522219 | Yahoo IM: z00dax | Gtalk: z00dax GnuPG Key : http://www.karan.org/publickey.asc ___ CentOS-virt mailing list CentOS-virt@centos.org http://lists.centos.org/mailman/listinfo/centos-virt ___ CentOS-virt mailing list CentOS-virt@centos.org http://lists.centos.org/mailman/listinfo/centos-virt
Re: [CentOS-virt] performance differences between kvm/xen
On 10/14/2010 07:48 AM, Tom Bishop wrote: I think xen is still on top in terms of performance and featuresnow that is indeed what it 'feels' like, but I'm quite keen on putting some numbers on that. having said that my experience in the past with kvm and my latest testing with 5.5 and KVM I can say that KVM has made great strides with the virtio drivers for the disk and nic, my latest vm's that I am using with those drivers are very snappy and so far I am very pleased.I'm I will try and get a machine up with centos dom0 and do some metrics. - KB ___ CentOS-virt mailing list CentOS-virt@centos.org http://lists.centos.org/mailman/listinfo/centos-virt
Re: [CentOS-virt] performance differences between kvm/xen
When you get the numbers please share, as I for one would be very interestedI have read some on the web but nothing as of late.I just don't have the time right now to go benchmark anything On Thu, Oct 14, 2010 at 1:59 PM, Karanbir Singh mail-li...@karan.orgwrote: On 10/14/2010 07:48 AM, Tom Bishop wrote: I think xen is still on top in terms of performance and featuresnow that is indeed what it 'feels' like, but I'm quite keen on putting some numbers on that. having said that my experience in the past with kvm and my latest testing with 5.5 and KVM I can say that KVM has made great strides with the virtio drivers for the disk and nic, my latest vm's that I am using with those drivers are very snappy and so far I am very pleased.I'm I will try and get a machine up with centos dom0 and do some metrics. - KB ___ CentOS-virt mailing list CentOS-virt@centos.org http://lists.centos.org/mailman/listinfo/centos-virt ___ CentOS-virt mailing list CentOS-virt@centos.org http://lists.centos.org/mailman/listinfo/centos-virt
Re: [CentOS-virt] performance differences between kvm/xen
Hi Karanbir, On 14 October 2010 19:59, Karanbir Singh mail-li...@karan.org wrote: On 10/14/2010 07:48 AM, Tom Bishop wrote: I think xen is still on top in terms of performance and featuresnow that is indeed what it 'feels' like, but I'm quite keen on putting some numbers on that. I have done some testing some time ago on one of the EQ machines that I got from hetzner.de. Full spec of the machine was as following: * Intel® Core™ i7-920 * 8 GB DDR3 RAM * 2 x 750 GB SATA-II HDD It's nothing big but even though results are quite interesting. All tests were performed on CentOS 5.5 x86_64 with PostgreSQL 8.4 (from CentOS repos). I have run some PostgreSQL PGBench tests as well as Bonnie++ tests. The PostgreSQL tests was divided into two tests having three goes (to get an idea of average). The commands I used for testing were: dropdb pgbench sync sleep 3 createdb pgbench sync sleep 3 pgbench -i -s 100 -U postgres -d pgbench sync sleep 3 pgbench -c 10 -t 5000 -s 100 -U postgres -d pgbench 2/dev/null sync \ sleep 3 pgbench -c 10 -t 5000 -s 100 -U postgres -d pgbench 2/dev/null \ sync sleep 3 pgbench -c 10 -t 5000 -s 100 -U postgres -d pgbench 2/dev/null \ sync sleep 3 Now results. First CentOS5/x86_64 without any virtualisation, without any PostgreSQL optimisation: -bash-3.2$ pgbench -c 10 -t 5000 -s 100 -U postgres -d pgbench 2/dev/null pghost: pgport: nclients: 10 nxacts: 5000 dbName: pgbench transaction type: TPC-B (sort of) scaling factor: 100 number of clients: 10 number of transactions per client: 5000 number of transactions actually processed: 5/5 tps = 141.191292 (including connections establishing) tps = 141.196776 (excluding connections establishing) -bash-3.2$ pgbench -c 10 -t 5000 -s 100 -U postgres -d pgbench 2/dev/null pghost: pgport: nclients: 10 nxacts: 5000 dbName: pgbench transaction type: TPC-B (sort of) scaling factor: 100 number of clients: 10 number of transactions per client: 5000 number of transactions actually processed: 5/5 tps = 156.479561 (including connections establishing) tps = 156.486222 (excluding connections establishing) -bash-3.2$ pgbench -c 10 -t 5000 -s 100 -U postgres -d pgbench 2/dev/null pghost: pgport: nclients: 10 nxacts: 5000 dbName: pgbench transaction type: TPC-B (sort of) scaling factor: 100 number of clients: 10 number of transactions per client: 5000 number of transactions actually processed: 5/5 tps = 164.880109 (including connections establishing) tps = 164.888009 (excluding connections establishing) Now after optimisation (shared_buffers, effective_cache_size etc.): pghost: pgport: nclients: 10 nxacts: 5000 dbName: pgbench transaction type: TPC-B (sort of) scaling factor: 100 number of clients: 10 number of transactions per client: 5000 number of transactions actually processed: 5/5 tps = 403.430951 (including connections establishing) tps = 403.474562 (excluding connections establishing) pghost: pgport: nclients: 10 nxacts: 5000 dbName: pgbench transaction type: TPC-B (sort of) scaling factor: 100 number of clients: 10 number of transactions per client: 5000 number of transactions actually processed: 5/5 tps = 336.060764 (including connections establishing) tps = 336.093214 (excluding connections establishing) pghost: pgport: nclients: 10 nxacts: 5000 dbName: pgbench transaction type: TPC-B (sort of) scaling factor: 100 number of clients: 10 number of transactions per client: 5000 number of transactions actually processed: 5/5 tps = 446.607705 (including connections establishing) tps = 446.664466 (excluding connections establishing) Now KVM based VM with 7GB RAM and 8 CPUs. Using virtio and LVM partitions as backend. PostgreSQL results *w/o* optimisation. -bash-3.2$ pgbench -c 10 -t 5000 -s 100 -U postgres -d pgbench 2/dev/null sync sleep 3 pgbench -c 10 -t 5000 -s 100 -U postgres -d pgbench 2/dev/null sync sleep 3 pgbench -c 10 -t 5000 -s 100 -U postgres -d pgbench 2/dev/null sync sleep 3 pghost: pgport: nclients: 10 nxacts: 5000 dbName: pgbench transaction type: TPC-B (sort of) scaling factor: 100 number of clients: 10 number of transactions per client: 5000 number of transactions actually processed: 5/5 tps = 124.578488 (including connections establishing) tps = 124.585776 (excluding connections establishing) pghost: pgport: nclients: 10 nxacts: 5000 dbName: pgbench transaction type: TPC-B (sort of) scaling factor: 100 number of clients: 10 number of transactions per client: 5000 number of transactions actually processed: 5/5 tps = 140.451736 (including connections establishing) tps = 140.463105 (excluding connections establishing) pghost: pgport: nclients: 10 nxacts: 5000 dbName: pgbench transaction type: TPC-B (sort of) scaling factor: 100 number of clients: 10 number of transactions per client: 5000 number of transactions actually processed: 5/5 tps = 148.091563 (including connections establishing)
