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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-users] HVM on 3.2 kernel hdd speed issue
On 3 April 2012 17:27, Mario <mario@xxxxxxxxxxxxxx> wrote: > On 04/03/2012 06:39 AM, Joseph Glanville wrote: >> >> On 3 April 2012 06:03, Mario<mario@xxxxxxxxxxxxxx> wrote: >>> >>> On 04/02/2012 09:55 PM, Joseph Glanville wrote: >>>> >>>> >>>> On 3 April 2012 05:48, Mario<mario@xxxxxxxxxxxxxx> wrote: >>>>> >>>>> >>>>> On 04/02/2012 09:27 PM, Joseph Glanville wrote: >>>>>> >>>>>> >>>>>> >>>>>> On 3 April 2012 05:17, Mario<mario@xxxxxxxxxxxxxx> wrote: >>>>>>> >>>>>>> >>>>>>> >>>>>>> On 04/02/2012 08:45 PM, Joseph Glanville wrote: >>>>>>>> >>>>>>>> >>>>>>>> >>>>>>>> >>>>>>>> On 2 April 2012 22:49, Mario<mario@xxxxxxxxxxxxxx> wrote: >>>>>>>>> >>>>>>>>> >>>>>>>>> >>>>>>>>> >>>>>>>>> On 04/02/2012 01:55 PM, Heiko Wundram wrote: >>>>>>>>>> >>>>>>>>>> >>>>>>>>>> >>>>>>>>>> >>>>>>>>>> >>>>>>>>>> Am 02.04.2012 13:33, schrieb Mario: >>>>>>>>>>> >>>>>>>>>>> >>>>>>>>>>> >>>>>>>>>>> >>>>>>>>>>> >>>>>>>>>>> On 04/02/2012 12:19 PM, Heiko Wundram wrote: >>>>>>>>>>>> >>>>>>>>>>>> >>>>>>>>>>>> >>>>>>>>>>>> >>>>>>>>>>>> >>>>>>>>>>>> Windows, of course, does not natively support PVonHVM in any way >>>>>>>>>>>> (except >>>>>>>>>>>> when using corresponding drivers to enable that), so if you get >>>>>>>>>>>> excessively slower I/O-speeds on "fully" virtualized Linux DomUs >>>>>>>>>>>> than >>>>>>>>>>>> you do on Windows DomUs which _don't_ have the corresponding >>>>>>>>>>>> PV-drivers >>>>>>>>>>>> installed, something else is amiss here; it'd help if you could >>>>>>>>>>>> describe >>>>>>>>>>>> your setup in a little more detail. >>>>>>>>>>>> >>>>>>>>>>> >>>>>>>>>>> Why are we still on PVonHVM subject? I do not want that, I want >>>>>>>>>>> regular HVM to work with linux domU's the same way it works with >>>>>>>>>>> windows domU's. I don't have the luxury to install custom drivers >>>>>>>>>>> on >>>>>>>>>>> some domU's, so there is no point in trying to force me to use >>>>>>>>>>> PVonHVM >>>>>>>>>>> because i can't. >>>>>>>>>>> So, anyone else please? :-) >>>>>>>>>> >>>>>>>>>> >>>>>>>>>> >>>>>>>>>> >>>>>>>>>> >>>>>>>>>> >>>>>>>>>> Read my last paragraph again, please: Linux fully virtualized >>>>>>>>>> DomUs >>>>>>>>>> (which use the corresponding NIC and disk emulation as implemented >>>>>>>>>> by >>>>>>>>>> qemu) shouldn't perform any different than a Windows DomU, >>>>>>>>>> I/O-performance wise, as both of them use the same infrastructure >>>>>>>>>> in >>>>>>>>>> Dom0 to do I/O (qemu process). You're saying that they are >>>>>>>>>> different, >>>>>>>>>> I/O-wise, so: please be a little more concrete _what_ the problem >>>>>>>>>> is >>>>>>>>>> that you're seeing. We don't have crystal balls handy, sorry. >>>>>>>>>> >>>>>>>>> >>>>>>>>> Its actualy quite simple, here is an example: Windows hvm domU disk >>>>>>>>> io >>>>>>>>> on >>>>>>>>> my >>>>>>>>> test server is ~60MB/s (sequential read or write). Linux HVM guests >>>>>>>>> (using >>>>>>>>> same config file template) on the same server gives ~10MB/s >>>>>>>>> (sequential >>>>>>>>> read >>>>>>>>> or write), i tried pretty much everything, from tuning scheduler to >>>>>>>>> changing >>>>>>>>> kernel. I am not sure what to do with it, other then roll back to >>>>>>>>> kernel >>>>>>>>> 2.6.34 on my dom0. >>>>>>>> >>>>>>>> >>>>>>>> >>>>>>>> >>>>>>>> >>>>>>>> Hieko and myself have told you what to do to get decent performance. >>>>>>>> Some examples of fully setup PVonHVM guests are available on my file >>>>>>>> mirror. >>>>>>>> http://mirror.orionvm.com.au >>>>>>>> >>>>>>>> Unless you use the PV drivers there isn't really a whole lot more I >>>>>>>> can do for you. >>>>>>>> >>>>>>>> I can't explain why performance would differ under 2.6.34 vs 3.2. >>>>>>>> This makes no sense as qemu-dm runs in userspace. You would have had >>>>>>>> to >>>>>>>> make >>>>>>>> some changes to the toolstack for this performance to differ. >>>>>>>> >>>>>>> >>>>>>> Performance difference between dom0 kernels aside, what I don't >>>>>>> understand >>>>>>> is why windows HVM domU works fine, while linux doesn't? >>>>>>> Isn't HVM supposed to work same for every guest, or does linux >>>>>>> actualy >>>>>>> have >>>>>>> something against HVM mode? I simply don't get it. >>>>>> >>>>>> >>>>>> >>>>>> >>>>>> It's definitely not an optimized use case however I have never seen as >>>>>> low performance as you are reporting. >>>>>> There are too many reasons to list as to why performance between >>>>>> Windows HVM and Linux HVM would differ. >>>>>> >>>>>> What Linux guests are you attempting to run? >>>>>> >>>>>> Joseph. >>>>>> >>>>> >>>>> Running a slackware guest, tried various kernels, did not make any >>>>> difference. Windows in question is 2008 R2. >>>> >>>> >>>> >>>> Try using a 3.0 guest kernel with XEN_PLATFORM_PCI=y and all of the >>>> Xen device drivers. >>>> This will enable PVHVM and you should be right as rain for performance. >>>> >>> >>> So what exactly do I do with linux guests that I don't have kernel >>> sources >>> for? :-) >> >> >> Guests older than 2.6.32 could be a problem. >> Everything else should be fine. >> Anything earlier than 2.6.32 you probably want to run in pure PV mode. >> > > I tried 2.6.37 and 3.2.7, same results. Ok it has become clear that nobody > knows, so lets forget about this one. I will keep xen for pv guests only, > everything else will go into vmware. Did you mean you had poor performance running 3.2.7 based HVM guests? Are you sure you set xen_platform_pci=1? (or left it out of the config) The 3.2.7 kernel assuming it was built correctly should automatically enable PV drivers which should have great performance. All current 3.0 and better binary distributions ship kernels that work perfectly in PVonHVM mode. I highly recommend you use the images I provided to assertain if you have a serious configuration problem or if there exists a bug/performance regression in your dom0 kernel. Joseph. > > Thanks anyway, > mario > > > > _______________________________________________ > Xen-users mailing list > Xen-users@xxxxxxxxxxxxx > http://lists.xen.org/xen-users -- Founder | Director | VP Research Orion Virtualisation Solutions | www.orionvm.com.au | Phone: 1300 56 99 52 | Mobile: 0428 754 846 _______________________________________________ Xen-users mailing list Xen-users@xxxxxxxxxxxxx http://lists.xen.org/xen-users
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