Re: [PATCH 4/5] KVM: Add hypercall queue for paravirt_ops implementation

Anthony Liguori wrote:

Avi Kivity wrote:

quoted

Anthony Liguori wrote:

quoted

Implemented a hypercall queue that can be used when paravirt_ops 
lazy mode
is enabled.  This patch enables queueing of MMU write operations and CR
updates.  This results in about a 50% bump in kernbench performance.
  

Nice!  But 50%? a kernel build is at native-25%, so we're now 25% 
faster than native?

Well, I haven't measured KVM to be 25% of native with kernbench :-)  
On my LS21 (AMD), I get:

I did, but using kbuild (a simple 'make' with defconfig), not 
kernbench.  I get (elapsed time) 308 sec for kvm and 243 sec for native.

Intel however is much faster than AMD due to the recent optimizations, 
and I guess we get some pagetable thrashing with kernbench vs. kbuild.

KVM
Elapsed Time 1054.39 (25.8237)
User Time 371.844 (8.57204)
System Time 682.61 (17.7778)
Percent CPU 99.8 (0.447214)  Sleeps 50115 (475.693)

KVM PV
Elapsed Time 595.85 (13.7058)
User Time 360.99 (9.56093)
System Time 234.704 (4.21283)
Percent CPU 99 (0)
Context Switches 46989.8 (328.277)
Sleep 47882.8 (242.583)

NATIVE
Elapsed Time 328.602 (0.212415)
User Time 304.364 (0.353171)
System Time 23.99 (0.325192)
Percent CPU 99 (0)
Context Switches 39785.2 (159.796)
Sleeps 46398.6 (311.466)

With Intel, we're still only about 60% of native to start out with.  
The PV patches take us to about 72%.

These numbers are pretty bad.  I'd like to improve them, even without PV.


-- 
error compiling committee.c: too many arguments to function


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