Currently the cache just deletes enough items when the cache is
full to make room for the new item being stored. This hasn't
been too much of a problem in practice but for things like running
piglit where we have thousands of unique shaders and all threads
being utilised we end up with a pretty big bottle neck.
With this change rather than just brute forcing our way to having
enough room for the new item, we instead grab 10% of the least
recently used items in the random directory we chose and delete
them all. This should only be around 0.04% of total cache items
but should hopefully releave some of the pressure on system calls
like fstatat().
Acked-by: Pierre-Eric Pelloux-Prayer <pierre-eric.pelloux-prayer@amd.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/11523>
Timothy Arceri
f58e6fee74