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

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

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
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
>