[PATCH 2/2] drm/vram-helper: Alternate between bottom-up and top-down placement

[Christian König]

Hi guys,

one thing you don't seem to have considered yet is that not setting the 
top-down flag also won't get you the bottom-up approach, but rather the 
best fit.

Additional to that the top-down allocations have quite a bit more CPU 
overhead since they don't walk the size tree, but the address tree in 
search for a fitting hole. Nirmoy is currently working on improving this.

Am 23.04.20 um 15:57 schrieb Gerd Hoffmann:
>> But cursor BOs are small, so they don't make much of a difference. What
>> is needed is space for 2 primary framebuffers during pageflips, with one
>> of them pinned. The other framebuffer can be located anywhere.
> The problem isn't the size.  The problem is dynamically allocated cursor
> BOs can also fragment vram, especially if top-bottom allocation is also
> used for large framebuffers so cursor BOs can end up somewhere in the
> middle of vram.

Well maybe instead of a ping/pong approach between top and bottom use a 
size based approach to place small BOs at the top and only the larger 
ones at the bottom (or the other way around).

Cheers,
Christian.