Re: [RFC] VMX CR3 cache

Gerd Hoffmann
2008-01-30T12:05:55Z

Avi Kivity wrote:

> [fairly amazing results. how do they compare to xen?]

Didn't benchmark it side-by-side yet. Most likely xenner is still
noticeable slower on 64bit (32bit should be roughly comparable). I also
wouldn't surprised if you see different results on different workloads.

xen mangles page table flags alot to make guests run fast despite the
frequent cr3 switches. It sets the global flag for userspace mappings
(which are identical in kernel/userspace page table tree) to avoid them
being flushed from tlb on every syscall enter/exit. I havn't tried to
do similar things in xenner because I don't track page tables in the
first place. I hope to get it to speed comparable to xen using
virtualization hardware features instead.

cheers,
Gerd

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