tree 1d0351afc0542f8f709f9ed7f6a445474b137a9e
parent d85dc283fa87353be10b11b463196d10eb49ca41
author aliguori <aliguori@c046a42c-6fe2-441c-8c8c-71466251a162> 1228853397 +0000
committer aliguori <aliguori@c046a42c-6fe2-441c-8c8c-71466251a162> 1228853397 +0000

KVM: Coalesced MMIO support

MMIO exits are more expensive in KVM or Xen than in QEMU because they 
involve, at least, privilege transitions.  However, MMIO write 
operations can be effectively batched if those writes do not have side 
effects.

Good examples of this include VGA pixel operations when in a planar 
mode.  As it turns out, we can get a nice boost in other areas too.  
Laurent mentioned a 9.7% performance boost in iperf with the coalesced 
MMIO changes for the e1000 when he originally posted this work for KVM.

Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>


git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@5961 c046a42c-6fe2-441c-8c8c-71466251a162