On 2016/4/29 11:01, Nadav Amit wrote:
Yang Zhang <yang.zhang.wz@xxxxxxxxx> wrote:
On 2016/4/28 23:32, Radim Krčmář wrote:
I think we are talking about extending KVM's IR-less x2APIC, when
standard x2APIC is the future.
Yes, Since IR is only useful for the external device, and 255 CPUs is enough to handle the interrupts from external devices. Besides, i think virtual VT-d will bring extra performance impaction for devices, so if IR-less X2APIC also works well with more than 255 VCPUs, maybe extending KVM with IR-less x2apic is not a bad idea.
So will you use x2APIC physical mode in this system?
Probably, cluster mode is the better choice.
Try not to send a multicast IPI to 400 cores in the VM...
Yes, a multicast IPI to so many cores is a disaster in VM, like
flush_tlb_others().
--
best regards
yang
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