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

[Chris Wilson]

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.
-Chris

-- 
Chris Wilson, Intel Open Source Technology Centre