On 16/03/2016 07:22, Suravee Suthikulpanit wrote: > This is mainly causing a large number of VMEXIT due to NPF. Got it, it's here in the manual: "System software is responsible for setting up a translation in the nested page table granting guest read and write permissions for accesses to the vAPIC Backing Page in SPA space. AVIC hardware walks the nested page table to check permissions, but does not use the SPA address specified in the leaf page table entry. Instead, AVIC hardware finds this address in the AVIC_BACKING_PAGE pointer field of the VMCB". Strictly speaking the address of the 0xFEE00000 translation is unnecessary and it could be all zeroes, but I suggest that you set up an APIC access page like Intel does (4k only), using the special memslot. The AVIC backing page can then point to lapic->regs. Thanks for the explanation! Paolo > CASE1: Using x86_set_memory_region() for AVIC backing page > > # ./perf-vmexit.sh 10 > [ perf record: Woken up 1 times to write data ] > [ perf record: Captured and wrote 2.813 MB perf.data.guest (30356 > samples) ] > > > Analyze events for all VMs, all VCPUs: > > VM-EXIT Samples Samples% Time% Min Time Max > Time Avg time > > interrupt 10042 66.30% 81.33% 0.43us > 202.50us 7.43us ( +- 1.20% ) > msr 5004 33.04% 15.76% 0.73us > 12.21us 2.89us ( +- 0.43% ) > pause 58 0.38% 0.18% 0.56us > 5.88us 2.92us ( +- 6.43% ) > npf 35 0.23% 2.01% 6.41us > 207.78us 52.70us ( +- 23.67% ) > nmi 4 0.03% 0.02% 2.31us > 4.67us 3.49us ( +- 14.26% ) > io 3 0.02% 0.70% 82.75us > 360.90us 214.28us ( +- 37.64% ) > avic_incomp_ipi 1 0.01% 0.00% 2.17us > 2.17us 2.17us ( +- 0.00% ) > > Total Samples:15147, Total events handled time:91715.78us. > > > CASE2: Using the lapic regs page for AVIC backing page. > > # ./perf-vmexit.sh 10 > [ perf record: Woken up 255 times to write data ] > [ perf record: Captured and wrote 509.202 MB perf.data.guest (5718856 > samples) ] > > > Analyze events for all VMs, all VCPUs: > > VM-EXIT Samples Samples% Time% Min Time Max > Time Avg time > > npf 1897710 99.33% 98.08% 1.09us > 243.22us 1.67us ( +- 0.04% ) > interrupt 7818 0.41% 1.44% 0.44us > 216.55us 5.97us ( +- 1.92% ) > msr 5001 0.26% 0.45% 0.68us > 12.58us 2.89us ( +- 0.50% ) > pause 25 0.00% 0.00% 0.71us > 4.23us 2.03us ( +- 10.76% ) > io 4 0.00% 0.03% 73.91us > 337.29us 206.74us ( +- 26.38% ) > nmi 1 0.00% 0.00% 5.92us > 5.92us 5.92us ( +- 0.00% ) > > Total Samples:1910559, Total events handled time:3229214.64us. > > Thanks, > Suravee > -- > To unsubscribe from this list: send the line "unsubscribe kvm" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html > -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
