[Intel-gfx] sna: Experimental support for write-combining mmaps (wc-mmap)

[Sedat Dilek]

On Fri, Nov 7, 2014 at 11:43 AM, Chris Wilson <chris at chris-wilson.co.uk> wrote:
> On Fri, Nov 07, 2014 at 11:35:01AM +0100, Sedat Dilek wrote:
>> On Fri, Nov 7, 2014 at 11:29 AM, Chris Wilson <chris at chris-wilson.co.uk> wrote:
>> > On Fri, Nov 07, 2014 at 11:08:41AM +0100, Sedat Dilek wrote:
>> >> Hi,
>> >>
>> >> I am playing with wc-mmap [1]... (and sent a trivial patch [0]).
>> >>
>> >> Inspecting my logs...
>> >>
>> >> $ egrep 'wc|mmap'
>> >> logs/build-and-install-log_XF86-Video-Intel-v2-99-916-137-g0aa2edb_WCMMAP_llvm-3-4-2.txt
>> >>   Experimental support: TearFree mmap(wc)
>> >>
>> >> $ egrep -i 'wc|mmap|write|comb' /var/log/Xorg.0.log
>> >> [ EMPTY ]
>> >>
>> >> TearFree [1] can be set via an option in xorg.conf.
>> >> Doing a very quick look into the sources, such a flag/option is not recognized.
>> >>
>> >> How do I see if wc-mmap is enabled/active on my desktop?
>> >
>> > Er, hopefully you don't notice anything except it speeds up certain
>> > operations (quite considerably) :). You have to enable the DBG output to
>> > see it in action, as it is quite a lowlevel feature (i.e. how we
>> > interact with the kernel) and should not add any user visible features.
>> > However, it does also require the kernel patch for it to be enabled.
>>
>> Can you point me to that kernel-patch?
>> Is Linux v3.18-rc2+ good enough or do I need d-i-l-n / d-i-n?
>

Hmm... against which trees are those patches?

> http://patchwork.freedesktop.org/patch/35049/
"drm/i915: Broaden application of set-domain(GTT)"

...is not applicable against d-i-f or d-i-n.

> http://patchwork.freedesktop.org/patch/35471/
"drm/i915: Support creation of unbound wc user mappings for objects"

That's good for both.

- Sedat -