• Christian Borntraeger's avatar
    KVM: s390: set halt polling to 80 microseconds · c4a8de35
    Christian Borntraeger authored
    on s390 we disabled the halt polling with commit 920552b2
    ("KVM: disable halt_poll_ns as default for s390x"), as floating
    interrupts would let all CPUs have a successful poll, resulting
    in much higher CPU usage (on otherwise idle systems).
    
    With the improved selection of polls we can now retry halt polling.
    Performance measurements with different choices like 25,50,80,100,200
    microseconds showed that 80 microseconds seems to improve several cases
    without increasing the CPU costs too much. Higher values would improve
    the performance even more but increased the cpu time as well.
    So let's start small and use this value of 80 microseconds on s390 until
    we have a better understanding of cost/benefit of higher values.
    Acked-by: default avatarCornelia Huck <cornelia.huck@de.ibm.com>
    Signed-off-by: default avatarChristian Borntraeger <borntraeger@de.ibm.com>
    Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
    c4a8de35
kvm_host.h 18.7 KB