[kvm-devel] [PATCH 0/2][RFC][v2] Batch writes to MMIO

[Laurent V. <Lau...@bu...>]

These two patches allow to batch writes to MMIO.

When kernel has to send MMIO writes to userspace, it stores them
in memory until it has to pass the hand to userspace for another
reason. This avoids to have too many context switches on operations
that can wait.

These patches introduce an ioctl() to define MMIO allowed to be delayed.

I made some bentchmark with iperf and e1000:

average on 10 runs

WITH            WITHOUT
PATCH		PATCH

257.2 MB/s      193.7 MB/s      33% faster

I've measured host_state_reload on WinXP boot:

WITH            WITHOUT
PATCH		PATCH

561397          739708          24% less

I've measured host_state_reload on a VGA text scroll:

WITH            WITHOUT
PATCH		PATCH

3976242         13779849        70% less...

[PATCH 1/2] kvm: Batch writes to MMIO
	- kernel part

[PATCH 2/2] kvm-userspace: Batch writes to MMIO
	- userspace part

Signed-off-by: Laurent Vivier <Lau...@bu...>