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

Anthony Liguori wrote:

quoted

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.

kernbench is a little different.  It does a find over the kernel 
source tree to attempt to get as much of the kernel in the page cache 
as possible.  It also uses -j4 by default.

quoted

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

I agree.  Do you know what's missing at this point?  There isn't a 
whole lot of state saving going on for the light weight exit paths for 
SVM.

The SVM code doesn't even have a lightweight vmexit path.  For every 
vmexit, it does the entire thing, including vmload/vmsave, fpu switch 
(if needed), segment reloading, and msr reloading.  It could use a lot 
of work.

For kbuild vs. kernbench, I suspect that -j4 causes the shadow page 
table cache to thrash.  1024 pages may be enough for a single instance 
but not -j4.  Hopefully replacing the eviction algorithm (currently 
FIFO) will help.  Otherwise we'll need to resize the cache again.

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


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