[PATCH v2] drm/i915/gvt: implement per-vm mmio switching optimization

[Zhenyu Wang]

On 2017.05.04 10:52:38 +0800, changbin.du at intel.com wrote:
> From: Changbin Du <changbin.du at intel.com>
> 
> Commit ab9da627906a ("drm/i915: make context status notifier head be
> per engine") gives us a chance to inspect every single request. Then
> we can eliminate unnecessary mmio switching for same vGPU. We only
> need mmio switching for different VMs (including host).
> 
> This patch introduced a new general API intel_gvt_switch_mmio() to
> replace the old intel_gvt_load/restore_render_mmio(). This function
> can be further optimized for vGPU to vGPU switching.
> 
> To support individual ring switch, we track the owner who occupy
> each ring. When another VM or host request a ring we do the mmio
> context switching. Otherwise no need to switch the ring.
> 
> This optimization is very useful if only one guest has plenty of
> workloads and the host is mostly idle. The best case is no mmio
> switching will happen.
> 
> v2:
>   o fix missing ring switch issue. (chuanxiao)
>   o support individual ring switch.
> 
> Signed-off-by: Changbin Du <changbin.du at intel.com>
> Reviewed-by: Chuanxiao Dong <chuanxiao.dong at intel.com>
> ---

Applied on -next, thx!

-- 
Open Source Technology Center, Intel ltd.

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