[Intel-gfx] [PATCH 1/2] drm/i915: ignore posting read when using vgpu

[Li, Weinan Z]

I am not sure if native driver still need POSTING_READ action. But for guest we can remove it directly.
Search the code, there are still upon 270 hints use POSTING_READ. 
For guest OS, one frequent POSTING_READ_FW action is in irq handler, it will impact the performance if there is heavy interrupts(like media reference usage.)

Thanks.
Best Regards.
Weinan, LI


> -----Original Message-----
> From: Chris Wilson [mailto:chris at chris-wilson.co.uk]
> Sent: Wednesday, January 25, 2017 3:13 PM
> To: Li, Weinan Z <weinan.z.li at intel.com>
> Cc: intel-gfx at lists.freedesktop.org; intel-gvt-dev at lists.freedesktop.org
> Subject: Re: [Intel-gfx] [PATCH 1/2] drm/i915: ignore posting read when
> using vgpu
> 
> On Wed, Jan 25, 2017 at 02:04:55PM +0800, Weinan Li wrote:
> > No need to do posting read when vgpu actived.
> 
> No. This is bloat for no gain. Almost all of those posting reads are superfluous
> anyway.
> -Chris
> 
> --
> Chris Wilson, Intel Open Source Technology Centre