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linux/arch/s390/kvm
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Wanpeng Li d73eb57b80 KVM: Boost vCPUs that are delivering interrupts 
Inspired by commit 9cac38dd5d (KVM/s390: Set preempted flag during
vcpu wakeup and interrupt delivery), we want to also boost not just
lock holders but also vCPUs that are delivering interrupts. Most
smp_call_function_many calls are synchronous, so the IPI target vCPUs
are also good yield candidates.  This patch introduces vcpu->ready to
boost vCPUs during wakeup and interrupt delivery time; unlike s390 we do
not reuse vcpu->preempted so that voluntarily preempted vCPUs are taken
into account by kvm_vcpu_on_spin, but vmx_vcpu_pi_put is not affected
(VT-d PI handles voluntary preemption separately, in pi_pre_block).

Testing on 80 HT 2 socket Xeon Skylake server, with 80 vCPUs VM 80GB RAM:
ebizzy -M

            vanilla     boosting    improved
1VM          21443       23520         9%
2VM           2800        8000       180%
3VM           1800        3100        72%

Testing on my Haswell desktop 8 HT, with 8 vCPUs VM 8GB RAM, two VMs,
one running ebizzy -M, the other running 'stress --cpu 2':

w/ boosting + w/o pv sched yield(vanilla)

            vanilla     boosting   improved
              1570         4000      155%

w/ boosting + w/ pv sched yield(vanilla)

            vanilla     boosting   improved
              1844         5157      179%

w/o boosting, perf top in VM:

 72.33%  [kernel]       [k] smp_call_function_many
  4.22%  [kernel]       [k] call_function_i
  3.71%  [kernel]       [k] async_page_fault

w/ boosting, perf top in VM:

 38.43%  [kernel]       [k] smp_call_function_many
  6.31%  [kernel]       [k] async_page_fault
  6.13%  libc-2.23.so   [.] __memcpy_avx_unaligned
  4.88%  [kernel]       [k] call_function_interrupt

Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Radim Krčmář <rkrcmar@redhat.com>
Cc: Christian Borntraeger <borntraeger@de.ibm.com>
Cc: Paul Mackerras <paulus@ozlabs.org>
Cc: Marc Zyngier <maz@kernel.org>
Signed-off-by: Wanpeng Li <wanpengli@tencent.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2019-07-20 09:00:45 +02:00
..
diag.c KVM: s390: add vcpu stat counters for many instruction 2018-01-24 16:49:02 +01:00
gaccess.c treewide: Use array_size() in vmalloc() 2018-06-12 16:19:22 -07:00
gaccess.h KVM: s390: Remove redundant license text 2017-12-06 09:18:42 +01:00
guestdbg.c KVM: s390: introduce defines for control registers 2018-05-17 09:02:27 +02:00
intercept.c KVM: s390: add exit io request stats and simplify code 2018-03-14 19:21:11 +00:00
interrupt.c KVM: Boost vCPUs that are delivering interrupts 2019-07-20 09:00:45 +02:00
irq.h KVM: s390: Remove redundant license text 2017-12-06 09:18:42 +01:00
Kconfig * ARM: support for SVE and Pointer Authentication in guests, PMU improvements 2019-05-17 10:33:30 -07:00
kvm-s390.c ARM: 2019-07-12 15:35:14 -07:00
kvm-s390.h KVM: s390: add the GIB and its related life-cyle functions 2019-02-05 14:29:23 +01:00
Makefile KVM: s390: Remove redundant license text 2017-12-06 09:18:42 +01:00
priv.c s390: ap: kvm: add PQAP interception for AQIC 2019-07-02 16:00:27 +02:00
sigp.c KVM: s390: introduce and use kvm_s390_test_cpuflags() 2018-01-24 17:46:42 +01:00
trace-s390.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
trace.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
vsie.c KVM: s390: vsie: Return correct values for Invalid CRYCB format 2019-04-29 09:01:22 +02:00