[Intel-gfx] [PATCH] drm/i915: Disable shrinker for non-swapped backed objects

[Daniel Vetter]

On Tue, Nov 24, 2015 at 11:17:38PM +0000, Chris Wilson wrote:
> On Tue, Nov 24, 2015 at 06:15:47PM +0100, Daniel Vetter wrote:
> > On Mon, Nov 23, 2015 at 09:20:24AM +0000, Chris Wilson wrote:
> > > If the system has no available swap pages, we cannot make forward
> > > progress in the shrinker by releasing active pages, only by releasing
> > > purgeable pages which are immediately reaped. Take total_swap_pages into
> > > account when counting up available objects to be shrunk and subsequently
> > > shrinking them. By doing so, we avoid unbinding objects that cannot be
> > > shrunk and so wasting CPU cycles flushing those objects from the GPU to
> > > the system and then immediately back again (as they will more than
> > > likely be reused shortly after).
> > > 
> > > Based on a patch by Akash Goel.
> > > 
> > > Reported-by: Akash Goel <akash.goel at intel.com>
> > > Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
> > > Cc: Akash Goel <akash.goel at intel.com>
> > > Cc: sourab.gupta at intel.com
> > 
> > Cc: linux-mm at kvack.org should be done on this one, just in case they have
> > ideas for proper interfaces for this. Which might be, given that Jerome
> > Glisse is working on swaput-to-vram and other fun stuff like that.
> > 
> > Also, how does stuff like zswap (or whatever "compress my swap in memory"
> > is called again) factor in here? Iirc Android very much does use that.
> 
> It doesn't. We would need
> 
> #include <linux/frontswap.h>
> 
> static bool swap_available(void)
> {
> 	return total_swap_pages || frontswap_enabled;
> }
> 
> But if that then returns true for Android it seems the primary usecase
> is invalidated.

Well swapping to frontswap should be ok. Trashing not so much, and if we
do that I suspect there's something really loopsided with memory usage
balancing going on ... Does the android workload have your "only shrink
inactive" patch already?
-Daniel
-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch