Re: [PATCH] drm/ttm: Fix GPU MM stats during pool shrinking

[Matthew Brost <matthew.brost@intel.com>]

On Fri, May 01, 2026 at 09:12:31PM -0700, Matthew Brost wrote:
> On Fri, May 01, 2026 at 05:05:14PM -0700, Kenneth Crudup wrote:
> > 
> > On 5/1/26 15:30, Matthew Brost wrote:
> > 
> > > TTM pool shrinking frees pages by calling __free_pages() directly,
> > > which bypasses updates to NR_GPU_ACTIVE and leaves GPU MM accounting
> > > out of sync.
> > > 
> > > Introduce a helper, __free_pages_gpu_account(), and use it for all page
> > > frees in ttm_pool.c so GPU MM statistics are updated consistently.
> > 
> > OK, so why/how does "bonnie++" increase the GPU Memory size?
> > 
> 
> Well, it shouldn’t. What bonnie++ does is basically consume system
> memory, triggering reclaim, which in turn will evict GPU BOs that exist
> when the display is open. Thanks for pointing me to bonnie++ - this,
> plus running something like the WebGL Aquarium in Chrome, is a very nice
> test case for Xe/DRM shrinkers.
> 
> > ----
> > SwapTotal:      33554428 kB
> > MemTotal:       32345672 kB
> > GPUReclaim:       621568 kB
> > GPUActive:        453592 kB
> > 
> > SwapTotal:      33554428 kB
> > MemTotal:       32345672 kB
> > GPUActive:       5554976 kB
> > GPUReclaim:        12716 kB
> > 
> > SwapTotal:      33554428 kB
> > MemTotal:       32345672 kB
> > GPUActive:      18407272 kB
> > GPUReclaim:          884 kB
> > 
> > SwapTotal:      33554428 kB
> > MemTotal:       32345672 kB
> > GPUActive:      24022916 kB
> > GPUReclaim:          716 kB
> > 
> > SwapTotal:      33554428 kB
> > MemTotal:       32345672 kB
> > GPUActive:      25258248 kB
> > GPUReclaim:        16032 kB
> > 
> > SwapTotal:      33554428 kB
> > MemTotal:       32345672 kB
> > GPUActive:      28207188 kB
> > GPUReclaim:         3684 kB
> > ----
> > 
> > ... and I'm now not so sure the patch is working ... this after a 2nd bonnie
> > run:
> 
> It doesn’t appear that it is. I can recreate what you’re seeing with
> this patch alone on drm-tip. I originally coded this patch on top of a
> local fix to avoid the TTM shrinker allocating higher-order folios when

s/allocating/spliting

Matt

> reclaiming memory—this is working there. I falsely assumed it would work
> on drm-tip as well. Let me ensure I have a standalone fix for GPUActive
> accounting first, then apply my TTM shrinker fix on top.
> 
> Matt
> 
> > 
> > ----
> > GPUActive:      44357100 kB
> > SwapTotal:      33554428 kB
> > MemTotal:       32345672 kB
> > GPUReclaim:        94864 kB
> > 
> > GPUActive:      44373904 kB
> > SwapTotal:      33554428 kB
> > MemTotal:       32345672 kB
> > GPUReclaim:        94996 kB
> > 
> > GPUActive:      44354940 kB
> > SwapTotal:      33554428 kB
> > MemTotal:       32345672 kB
> > GPUReclaim:        98048 kB
> > 
> > GPUActive:      44769340 kB
> > SwapTotal:      33554428 kB
> > MemTotal:       32345672 kB
> > GPUReclaim:       122996 kB
> > ----
> > 
> > -Kenny
> > 
> > -- 
> > Kenneth R. Crudup / Sr. SW Engineer, Scott County Consulting, Orange County
> > CA
> >