I dont know, it depends of the game and if this part of the code have impact on fps...
Kind of thread locks maybe? On 6 Jan 2017 11:23 p.m., "Marius Steffen" <marius.stef...@posteo.de> wrote: > I think I've read about this on this mailing list, because when playing > Crysis 3, my VM kept crashing (more precise: the game didn't even start), > until I set 'options kvm ignore_msrs=1' in modprobe.d .conf file. > When switching to Win8, will the performance be better? > > > Thanks, > > Marius > > Am 06.01.2017 um 14:52 schrieb Quentin Deldycke: > > For adding a bit on this subjects, some games (blizzard games, tomb raider > at it's launch) use a lot of msrs during run. > It seems this is made for their anti-cheat / hack systems. > > Heroes of the storm, SC2 are spamming these msrs. This reduce performance > quite hardly. > > Funny thing: This "bug" does not apply to win8 / win7 :) > > For reference we spoke about such in this thread a long time ago: > https://www.redhat.com/archives/vfio-users/2016-May/msg00134.html > > > The kernel spam of such error at Heroes of the storm login screen: > [136995.284205] kvm [6799]: vcpu2, guest rIP: 0xfffff8016e757733 > kvm_set_msr_common: MSR_IA32_DEBUGCTLMSR 0x1, nop > [136995.284217] kvm [6799]: vcpu2, guest rIP: 0xfffff8016e757733 > kvm_set_msr_common: MSR_IA32_DEBUGCTLMSR 0x1, nop > [137000.285330] kvm_get_msr_common: 302015 callbacks suppressed > [137000.285337] kvm [6799]: vcpu5, guest rIP: 0xfffff8016e75779c ignored > rdmsr: 0x1c9 > [137000.285342] kvm [6799]: vcpu5, guest rIP: 0xfffff8016e7577aa ignored > rdmsr: 0x680 > [137000.285344] kvm [6799]: vcpu5, guest rIP: 0xfffff8016e7577c1 ignored > rdmsr: 0x6c0 > > > -- > Deldycke Quentin > > > On 6 January 2017 at 14:07, Thomas Lindroth <thomas.lindr...@gmail.com> > wrote: > >> On 01/06/2017 01:00 PM, Marius Steffen wrote: >> > Is there anything I can do to a) find the cause of this bad performance >> > b) make my VM perform better? >> >> One thing you can try is to run the game with poor performance and at the >> same time run "perf kvm --host stat live" on the host. This will show how >> many VM-EXIT kvm performs. VM-EXIT means the guest has done something the >> hardware virtualisation can't handle, like accessing MSR or virtual IO. >> >> Some workloads will perform badly because they cause a lot of VM-EXIT. >> Perf will tell you why a VM-EXIT was performed. The more common causes are >> IO_INSTRUCTION and EPT_MISCONFIG. IO_INSTRUCTION means the guest tried to >> access an x86 ioport and EPT_MISCONFIG seems to be an odd name for access >> to memory mapped io. Sometimes a lot of time is spent in HLT but that's >> normal. It only means the guest OS has nothing to do and goes idle. >> >> By running "perf kvm --host stat live --event=ioport" you can check which >> ioport is accessed and "perf kvm --host stat live --event=mmio" shows >> which address was accessed for memory mapped io. >> >> If you see that an mmio address is accessed a lot and want to find out >> what >> it is you can run "virsh qemu-monitor-command <nameofvm> --hmp 'info >> mtree'" >> to get a list of the memory layout of the VM. Unfortunately I don't know >> of any way to get a similar list of ioports. >> >> As an example on my system some games like Rise of the Tomb Raider and >> Assassin's Creed Unity will access ioport 0xb008 more than 200,000 >> times/sec >> and those games will have poor performance compared to native. Qemu >> hardcode the acpi timer to ioport 0xb008 and those games excessively read >> the hardware timer. I haven't figured out any way to work around the >> problem >> but I run games with vsync on and even with the decreased performance I >> get >> 60fps in those titles. >> >> _______________________________________________ >> vfio-users mailing list >> vfio-users@redhat.com >> https://www.redhat.com/mailman/listinfo/vfio-users >> > > > > _______________________________________________ > vfio-users mailing > listvfio-users@redhat.comhttps://www.redhat.com/mailman/listinfo/vfio-users > > >
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