1. 30 1月, 2017 4 次提交
  2. 23 11月, 2016 2 次提交
    • C
      KVM: s390: handle floating point registers in the run ioctl not in vcpu_put/load · e1788bb9
      Christian Borntraeger 提交于
      Right now we switch the host fprs/vrs in kvm_arch_vcpu_load and switch
      back in kvm_arch_vcpu_put. This process is already optimized
      since commit 9977e886 ("s390/kernel: lazy restore fpu registers")
      avoiding double save/restores on schedule. We still reload the pointers
      and test the guest fpc on each context switch, though.
      
      We can minimize the cost of vcpu_load/put by doing the test in the
      VCPU_RUN ioctl itself. As most VCPU threads almost never exit to
      userspace in the common fast path, this allows to avoid this overhead
      for the common case (eventfd driven I/O, all exits including sleep
      handled in the kernel) - making kvm_arch_vcpu_load/put basically
      disappear in perf top.
      
      Also adapt the fpu get/set ioctls.
      Signed-off-by: NChristian Borntraeger <borntraeger@de.ibm.com>
      Reviewed-by: NCornelia Huck <cornelia.huck@de.ibm.com>
      Signed-off-by: NChristian Borntraeger <borntraeger@de.ibm.com>
      e1788bb9
    • C
      KVM: s390: handle access registers in the run ioctl not in vcpu_put/load · 31d8b8d4
      Christian Borntraeger 提交于
      Right now we save the host access registers in kvm_arch_vcpu_load
      and load them in kvm_arch_vcpu_put. Vice versa for the guest access
      registers. On schedule this means, that we load/save access registers
      multiple times.
      
      e.g. VCPU_RUN with just one reschedule and then return does
      
      [from user space via VCPU_RUN]
      - save the host registers in kvm_arch_vcpu_load (via ioctl)
      - load the guest registers in kvm_arch_vcpu_load (via ioctl)
      - do guest stuff
      - decide to schedule/sleep
      - save the guest registers in kvm_arch_vcpu_put (via sched)
      - load the host registers in kvm_arch_vcpu_put (via sched)
      - save the host registers in switch_to (via sched)
      - schedule
      - return
      - load the host registers in switch_to (via sched)
      - save the host registers in kvm_arch_vcpu_load (via sched)
      - load the guest registers in kvm_arch_vcpu_load (via sched)
      - do guest stuff
      - decide to go to userspace
      - save the guest registers in kvm_arch_vcpu_put (via ioctl)
      - load the host registers in kvm_arch_vcpu_put (via ioctl)
      [back to user space]
      
      As the kernel does not use access registers, we can avoid
      this reloading and simply piggy back on switch_to (let it save
      the guest values instead of host values in thread.acrs) by
      moving the host/guest switch into the VCPU_RUN ioctl function.
      We now do
      
      [from user space via VCPU_RUN]
      - save the host registers in kvm_arch_vcpu_ioctl_run
      - load the guest registers in kvm_arch_vcpu_ioctl_run
      - do guest stuff
      - decide to schedule/sleep
      - save the guest registers in switch_to
      - schedule
      - return
      - load the guest registers in switch_to (via sched)
      - do guest stuff
      - decide to go to userspace
      - save the guest registers in kvm_arch_vcpu_ioctl_run
      - load the host registers in kvm_arch_vcpu_ioctl_run
      
      This seems to save about 10% of the vcpu_put/load functions
      according to perf.
      
      As vcpu_load no longer switches the acrs, We can also loading
      the acrs in kvm_arch_vcpu_ioctl_set_sregs.
      Suggested-by: NFan Zhang <zhangfan@linux.vnet.ibm.com>
      Reviewed-by: NCornelia Huck <cornelia.huck@de.ibm.com>
      Signed-off-by: NChristian Borntraeger <borntraeger@de.ibm.com>
      31d8b8d4
  3. 16 9月, 2016 1 次提交
  4. 08 9月, 2016 3 次提交
  5. 29 8月, 2016 1 次提交
  6. 26 8月, 2016 1 次提交
  7. 25 8月, 2016 1 次提交
  8. 12 8月, 2016 2 次提交
  9. 18 7月, 2016 1 次提交
  10. 01 7月, 2016 1 次提交
  11. 21 6月, 2016 11 次提交
  12. 20 6月, 2016 5 次提交
  13. 16 6月, 2016 1 次提交
  14. 13 6月, 2016 1 次提交
  15. 10 6月, 2016 5 次提交