Re: [PATCH 0/9] [RFC] fair-lru eviction

[Chris Wilson <chris@chris-wilson.co.uk>]

On Tue, 18 May 2010 23:11:42 +0200, Daniel Vetter <daniel.vetter@ffwll.ch> wrote:
> Hi all,
> 
> This patch series implements the fair-lru eviction Chris Wilson already
> posted with a twist. It's essentially the same idea & algorithm.
> Differnences versus his patch:
> - Doesn't do any allocations while scanning.
> - Implemented in drm_mm.c
> 
> In other words, this should also be usable by ttm. The idea is simple:
> Scan through the lru, marking objects as evictable until there is a
> large area of memory free/free-able. Then walk through all the scanned
> objects in reverse, checking which ones fall into this hole. Finally
> evicting them.
> 
> Comments, ideas highly welcome.

The next adaptation I did was to clean up evict_something to add objects
from the inactive, active&&!pinned&&!write, flushing&&!pinned,
active&&!pinned&&write lists. This reduces the logic in evict_something to
a single scan over the available objects in LRU order.

We still need the move-to-inactive-tail upon access by the CPU, and I
think it is acceptable to maintain our preference of the GPU over the CPU.
Recovering memory from the CPU is comparatively cheap.

Comparing 'while :; do yes > /tmp/yes; done & cairo-perf-trace', there is
no significant delta between the fair LRU and current. I'll rebase my
evict_something() on top of your drm_mm, and rerun the tests.

-- 
Chris Wilson, Intel Open Source Technology Centre