Pinning/customizing vcpu AND removing the balloon apparently solve the problem
2015-12-29 14:07 GMT+01:00 Quentin Deldycke <[email protected]>: > Hello, > > Little question about atop: Is this normal to have a usage of 50% in user > and 50% in guest when running a task on all cores of the vm? (windows > report 100% on all cores) > > With full vm on full dynticks cpus + cpuset and redirected pcie ssd + ahci > controlers. > > Note: for the main topic: using a 4970k like you, 16g of ram, 12 for the > guest. My debian with kde, spotify, network shares is full operational > using 2 cores, having 6 allocated to the vm. > > I am now using whole controllers to the vm, but i was using a simple .raw > file before, and i never had any problem of debian lags. Can you provide > the xml file? or any other information about how you start the vm? > > > -- > Deldycke Quentin > > > On 29 December 2015 at 11:52, thibaut noah <[email protected]> wrote: > >> Actually i have a lvm using the ssd for fedora os and a harddrive for the >> swap. >> >> 2015-12-29 11:50 GMT+01:00 thibaut noah <[email protected]>: >> >>> Sure but how do i do that? >>> I can check the memory usage on the guest using rivaturner ( i don't use >>> more than 9gB of ram, i have 16), may the problem come from the balloon >>> option at the end of the xml ? Dunno how to check the rest though. >>> >>> For disk io i use a separate ssd for the vm and all other disks are not >>> mount when i launch it (it will fail otherwise if i remember correctly). >>> But talking about swap i need to check where the swap for fedora is, >>> maybe there is something worth checking here. >>> >>> I already reduced the memory i assign to the windows vm because >>> otherwise it would fail, apparently fedora likes to take a lot of ram of >>> nothing. >>> >>> 2015-12-29 11:38 GMT+01:00 Karsten Elfenbein < >>> [email protected]>: >>> >>>> If it takes time to recover after exiting the VM I think you have a >>>> different problem than CPU pinning. >>>> While my Windows VM is idle all CPU cores are idle on the host as well. >>>> >>>> Time to recover sounds more like a system that swapped out memory to >>>> make room for the VM. After exiting it needs the swapped out process >>>> memory which takes time. >>>> Can you check the memory/swap/disk io usage? >>>> >>>> 2015-12-29 11:13 GMT+01:00 thibaut noah <[email protected]>: >>>> > I'll try to set the topology tonight. >>>> > Fedora still takes time to be fully operationnal after exiting >>>> windows, and >>>> > i use windows only not putting more load on fedora, weird. >>>> > My goal by tweaking the vcpu is to get the best possible performance >>>> i can >>>> > reach without crippling the host os. >>>> > dual xeon are indeed expensive, specially those with 3+ghz, dunno if >>>> i need >>>> > that much cpu for windows though i'm not sure, i can try by just using >>>> > 2physical cores and see how it goes for both os, would be nice if i >>>> could >>>> > apply the new patch to move my keyboard from guest to host T_T >>>> > >>>> > 2015-12-28 10:54 GMT+01:00 Karsten Elfenbein < >>>> [email protected]>: >>>> >> >>>> >> It just hands the layout of your CPU to the guest. So apps can decide >>>> >> on threading. >>>> >> >>>> >> Pinning the CPU to avoid CPU 0 and 4 will reduce the performance a >>>> bit >>>> >> as a complete physical core is reserved for the host OS. >>>> >> There are faster Desktop CPUs to compensate if needed but dual Xeon >>>> >> that can keep up in single thread performance are expensive and you >>>> >> would need 2 CPU + memory + board. >>>> >> >>>> >> >>>> >> >>>> >> 2015-12-28 10:24 GMT+01:00 Eddie Yen <[email protected]>: >>>> >> > >>>> >> > This should provide the guest some details of the provided vCPUs: >>>> >> > >>>> >> > <topology sockets='1' cores='3' threads='2'/> >>>> >> > >>>> >> > >>>> >> > I tested this method before, using the 4820K. >>>> >> > The result I got is the performance not get better that set whole >>>> >> > threads as >>>> >> > cores when tested 3DMark. >>>> >> > But I didn't pinning 0 and 4 thread to host. >>>> >> > >>>> >> > I'll test it again soon. >>>> >> > >>>> >> > 2015-12-28 17:13 GMT+08:00 Karsten Elfenbein >>>> >> > <[email protected]>: >>>> >> >> >>>> >> >> Hi, >>>> >> >> >>>> >> >> that looks good. Processors 0 and 4 are not used in pinning and >>>> remain >>>> >> >> on the host OS. https://en.wikipedia.org/wiki/Hyper-threading >>>> >> >> Basically as soon as you load one OS CPU on a physical core the >>>> other >>>> >> >> HT core will be able to perform a lot less stuff. >>>> >> >> >>>> >> >> This should provide the guest some details of the provided vCPUs: >>>> >> >> <topology sockets='1' cores='3' threads='2'/> >>>> >> >> >>>> >> >> >>>> >> >> 2015-12-28 6:55 GMT+01:00 thibaut noah <[email protected]>: >>>> >> >> > So is this the right emulation? If i understand correctly what >>>> i'm >>>> >> >> > trying to >>>> >> >> > get is a 3cores with 2threads per core ? (so 6cores pinned?) >>>> >> >> > I don't have that much knowledge in cpu so i'm kinda lost here. >>>> >> >> > >>>> >> >> > <cputune> >>>> >> >> > <vcpupin vcpu='0' cpuset='1'/> >>>> >> >> > <vcpupin vcpu='1' cpuset='2'/> >>>> >> >> > <vcpupin vcpu='2' cpuset='3'/> >>>> >> >> > <vcpupin vcpu='3' cpuset='5'/> >>>> >> >> > <vcpupin vcpu='4' cpuset='6'/> >>>> >> >> > <vcpupin vcpu='5' cpuset='7'/> >>>> >> >> > </cputune> >>>> >> >> > >>>> >> >> > 2015-12-26 18:53 GMT+01:00 Karsten Elfenbein >>>> >> >> > <[email protected]>: >>>> >> >> >> >>>> >> >> >> check that the 2 cores for the host OS are on the same >>>> physical core >>>> >> >> >> and that the VM does not use those 2 processors with the same >>>> core >>>> >> >> >> id >>>> >> >> >> >>>> >> >> >> cat /proc/cpuinfo | grep -e processor -e 'core id' >>>> >> >> >> >>>> >> >> >> CPU 0-3 should be the core 0-3 >>>> >> >> >> CPU 4-7 should be the core 0-3 again with HT >>>> >> >> >> >>>> >> >> >> so leaving out CPU 0 and 4 should keep core 0 idle and the >>>> host OS >>>> >> >> >> responsive >>>> >> >> >> >>>> >> >> >> taskset 1-3,5-7 startVM.sh >>>> >> >> >> >>>> >> >> >> Karsten >>>> >> >> >> >>>> >> >> >> 2015-12-26 12:56 GMT+01:00 Eddie Yen <[email protected]>: >>>> >> >> >> > Pining CPU can reduce the happening that host and guest >>>> using the >>>> >> >> >> > same >>>> >> >> >> > thread at the same time. >>>> >> >> >> > >>>> >> >> >> > And I don't know which program you're using on Fedora, so I >>>> don't >>>> >> >> >> > have >>>> >> >> >> > quite >>>> >> >> >> > answer that 2 threads is enough for host or not. >>>> >> >> >> > It's all depends on your usage case. >>>> >> >> >> > >>>> >> >> >> > 2015-12-26 19:44 GMT+08:00 thibaut noah < >>>> [email protected]>: >>>> >> >> >> >> >>>> >> >> >> >> My cpu is a i7 4790k, is pinning the cpu usefull ? I'll try >>>> to >>>> >> >> >> >> derp >>>> >> >> >> >> a >>>> >> >> >> >> bit >>>> >> >> >> >> with the vcpu thing, just afraid 2 threads aren't enough for >>>> >> >> >> >> fedora >>>> >> >> >> >> :/ >>>> >> >> >> >> >>>> >> >> >> >> 2015-12-26 11:59 GMT+01:00 Eddie Yen <[email protected] >>>> >: >>>> >> >> >> >>> >>>> >> >> >> >>> I forgot your CPU type, so I don't know about your case. >>>> >> >> >> >>> >>>> >> >> >> >>> But, as I'm using 4820K, I usually using 4 to 6 threads >>>> gave to >>>> >> >> >> >>> VM, >>>> >> >> >> >>> only >>>> >> >> >> >>> use 2 threads for Fedora host. >>>> >> >> >> >>> And most important is vCPU tweaks, especially CPU topology >>>> and >>>> >> >> >> >>> Hyper-V. >>>> >> >> >> >>> >>>> >> >> >> >>> For me, I usually set topology as "sockets=1 cores=6 >>>> threads=1" >>>> >> >> >> >>> if >>>> >> >> >> >>> using >>>> >> >> >> >>> 6 threads from host. >>>> >> >> >> >>> Then set cpuset= to let vCPU worked on pointed CPU threads. >>>> >> >> >> >>> >>>> >> >> >> >>> IME, set all threads as vCPU cores can got better >>>> performance on >>>> >> >> >> >>> Windows >>>> >> >> >> >>> 10. >>>> >> >> >> >>> >>>> >> >> >> >>> 2015-12-26 18:00 GMT+08:00 thibaut noah >>>> >> >> >> >>> <[email protected]>: >>>> >> >> >> >>>> >>>> >> >> >> >>>> Hello guys merry christmas ! o/ >>>> >> >> >> >>>> My current issue is vm and host optimization, i use my >>>> windows >>>> >> >> >> >>>> 10 >>>> >> >> >> >>>> vm >>>> >> >> >> >>>> for >>>> >> >> >> >>>> gaming purposes only (like most of us i think), problem >>>> is, to >>>> >> >> >> >>>> keep >>>> >> >> >> >>>> my >>>> >> >> >> >>>> performances on windows high i drain too much ressources >>>> on my >>>> >> >> >> >>>> fedora >>>> >> >> >> >>>> host >>>> >> >> >> >>>> thus making it almost useless (also when leaving the vm i >>>> most >>>> >> >> >> >>>> of >>>> >> >> >> >>>> the >>>> >> >> >> >>>> time >>>> >> >> >> >>>> found myself unable to use fedora at all so i have to >>>> >> >> >> >>>> reboot...). >>>> >> >> >> >>>> So is it possible to improve performances to the max on >>>> the >>>> >> >> >> >>>> guest >>>> >> >> >> >>>> without almost killing the host ? >>>> >> >> >> >>>> Should i consider switching my gear for a bi-xeon? (to >>>> assign >>>> >> >> >> >>>> one >>>> >> >> >> >>>> fully >>>> >> >> >> >>>> to the host and one to the guest) >>>> >> >> >> >>>> I'm actually not sure about what happen here, does anyone >>>> ran >>>> >> >> >> >>>> into >>>> >> >> >> >>>> the >>>> >> >> >> >>>> same sort of issue? >>>> >> >> >> >>>> Have a good day >>>> >> >> >> >>>> >>>> >> >> >> >>>> _______________________________________________ >>>> >> >> >> >>>> vfio-users mailing list >>>> >> >> >> >>>> [email protected] >>>> >> >> >> >>>> https://www.redhat.com/mailman/listinfo/vfio-users >>>> >> >> >> >>>> >>>> >> >> >> >>> >>>> >> >> >> >> >>>> >> >> >> > >>>> >> >> >> > >>>> >> >> >> > _______________________________________________ >>>> >> >> >> > vfio-users mailing list >>>> >> >> >> > [email protected] >>>> >> >> >> > https://www.redhat.com/mailman/listinfo/vfio-users >>>> >> >> >> > >>>> >> >> > >>>> >> >> > >>>> >> > >>>> >> > >>>> > >>>> > >>>> >>> >>> >> >> _______________________________________________ >> vfio-users mailing list >> [email protected] >> https://www.redhat.com/mailman/listinfo/vfio-users >> >> >
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