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

[Chris Wilson]

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?

http://patchwork.freedesktop.org/patch/35049/
http://patchwork.freedesktop.org/patch/35471/
-Chris

-- 
Chris Wilson, Intel Open Source Technology Centre