OK, I'll have a try, thank you :) 2015-12-28 17:54 GMT+08:00 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 > >> >> > > >> > > >> > > > > > >
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