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[Stephen Finucane <sfinucan@xxxxxxxxxx>]

Public bug reported:

When hyper threading is enabled, the way emulator_threads_policy
allocates the extra cpu resource for emulator is not optimal.

The instance I use for testing is a 6-vcpu VM; before enable this
emulator_threads_policy, I reserve 6 cpu (actually 6 threads since we
enable hyper threading) in nova config,

 vcpu_pin_set=8,10,12,32,34,36

Now when we enable emulator_threads_policy, in stead of adding one more
thread to this vcpu pin list in the nova config, I end up adding two
more sibling threads (on the same core)

 vcpu_pin_set=8,10,12,16,32,34,36,40

So I ended up using 2 more threads, but only of them is used for
emulator and the other thread is wasted.

Originally reported on Bugzilla - https://bugzilla.redhat.com/1534669

** Affects: nova
     Importance: Undecided
         Status: New

** Description changed:

  When hyper threading is enabled, the way emulator_threads_policy
  allocates the extra cpu resource for emulator is not optimal.
  
- The instance I use for testing is a 6-vcpu VM; before enable this emulator_threads_policy, I reserve 6 cpu (actually 6 threads since we enable hyper threading) in nova config,
- vcpu_pin_set=8,10,12,32,34,36
+ The instance I use for testing is a 6-vcpu VM; before enable this
+ emulator_threads_policy, I reserve 6 cpu (actually 6 threads since we
+ enable hyper threading) in nova config,
  
- Now when we enable emulator_threads_policy, in stead of adding one more thread to this vcpu pin list in the nova config, I end up adding two more sibling threads (on the same core)
-  vcpu_pin_set=8,10,12,16,32,34,36,40
+  vcpu_pin_set=8,10,12,32,34,36
+ 
+ Now when we enable emulator_threads_policy, in stead of adding one more
+ thread to this vcpu pin list in the nova config, I end up adding two
+ more sibling threads (on the same core)
+ 
+  vcpu_pin_set=8,10,12,16,32,34,36,40
  
  So I ended up using 2 more threads, but only of them is used for
  emulator and the other thread is wasted.
  
  Originally reported on Bugzilla - https://bugzilla.redhat.com/534669

** Description changed:

  When hyper threading is enabled, the way emulator_threads_policy
  allocates the extra cpu resource for emulator is not optimal.
  
  The instance I use for testing is a 6-vcpu VM; before enable this
  emulator_threads_policy, I reserve 6 cpu (actually 6 threads since we
  enable hyper threading) in nova config,
  
-  vcpu_pin_set=8,10,12,32,34,36
+  vcpu_pin_set=8,10,12,32,34,36
  
  Now when we enable emulator_threads_policy, in stead of adding one more
  thread to this vcpu pin list in the nova config, I end up adding two
  more sibling threads (on the same core)
  
   vcpu_pin_set=8,10,12,16,32,34,36,40
  
  So I ended up using 2 more threads, but only of them is used for
  emulator and the other thread is wasted.
  
- Originally reported on Bugzilla - https://bugzilla.redhat.com/534669
+ Originally reported on Bugzilla - https://bugzilla.redhat.com/1534669

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https://bugs.launchpad.net/bugs/1744965

Title:
  'emulator_threads_policy' doesn't work with 'vcpu_pin_set'

Status in OpenStack Compute (nova):
  New

Bug description:
  When hyper threading is enabled, the way emulator_threads_policy
  allocates the extra cpu resource for emulator is not optimal.

  The instance I use for testing is a 6-vcpu VM; before enable this
  emulator_threads_policy, I reserve 6 cpu (actually 6 threads since we
  enable hyper threading) in nova config,

   vcpu_pin_set=8,10,12,32,34,36

  Now when we enable emulator_threads_policy, in stead of adding one
  more thread to this vcpu pin list in the nova config, I end up adding
  two more sibling threads (on the same core)

   vcpu_pin_set=8,10,12,16,32,34,36,40

  So I ended up using 2 more threads, but only of them is used for
  emulator and the other thread is wasted.

  Originally reported on Bugzilla - https://bugzilla.redhat.com/1534669

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