[Xen-devel] [PATCH] VGA acceleration utilizing shadow logdirty functionality

["Huang, Xinmei" <xinmei.huang@xxxxxxxxx>]

Hi all, 

here's a patch for vga acceleration. Can anyone give some suggestions ?

Shadow log dirty mode is enabled to track vram pages dirty status.When
drawing guest graphic screen, VGA dm gets the dirty bitmap of mmio space
through one shadow control hypercall. VGA
dm updates dirty pages of vram according to the dirty bitmap.Hypervisor
marks the vram pages read-only for the guest, in order to log the write
access to these pages from the guest. Once a vram page is written and
logged by hypervisor, it becomes r/w for this guest. After returning the
dirty bitmap to VGA dm, hypervisor re-marks these vram pages read-only
for next round.

This patch would save the heavy overhead of current vram dirty
algorithm(compare between vram and vram copy of last round), albeit
brings overhead of ram page fault for dirty status log. 

Any suggesion will be really appreciated.

Thanks !

Attachment: vga.logdirty.patch
Description: vga.logdirty.patch

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