[Mesa-dev] [PATCH] anv/blorp: Emit depth flush and stall prior to HiZ clears

Chad Versace chadversary at chromium.org
Fri Aug 31 21:58:44 UTC 2018

On Fri 31 Aug 2018, Jason Ekstrand wrote:
> On Fri, Aug 31, 2018 at 4:35 PM Nanley Chery <[1]nanleychery at gmail.com> wrote:
>     If that doesn't fix it, I think it'd be good to comment that we've
>     observed this pipecontrol be necessary for 3DSTATE_WM_HZ_OP.
>  I'm happy to add some comments.  We just need to decide how big of a hammer to
> use.  Like I said above, in GL we pull out a pretty big one.

Speaking from prior experience, I support big flush hammers for hiz.
When a gpu hang happens, it can be incredibly difficult to diagnose it
as a hiz hang. It's better to prevent most of them with a large hammer
rather than diagnose them individually and try to prevent them with
several, single-focus tiny hammers.

Considering the impact of a gpu hang on Chrome (the entire OS may use
a single GL ctx, and for Vulkan it may do the same, using a small number
of  VkDevices), we should err on the side of avoiding the gpu hang
rather than err on the side of "too many flushes are bad".

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