963076 - Create a tile pool for tiled layers

Status: RESOLVED FIXED

(Core :: Graphics: Layers, defect)

Description

[Chris Lord [:cwiiis]]

The cost of allocation and deallocation during the display and interaction with an average page is higher than it needs to be when using the tiled layers backend. When a tiled layer buffer changes in size, tiles are discarded and immediately deallocated, and similarly, they are created on-demand. This showed up as a considerably performance hit when using shared memory on Android as opposed to local heap allocated memory (see bug 747811 comment #24).

We could mitigate the cost of allocating and deallocating tiles per transaction by keeping a pool of tiles on the layer manager and only deallocating after either a transaction ends, a threshold is reached, or both.

This will become especially important with gralloc-backed tiles, as the cost of gralloc'ing is usually a lot higher than either standard memory allocation or shm.

Comment 1

[Andreas Gal :gal]

Make sure you hook up the OOM hook. Otherwise sounds good.

Comment 2

[Benoit Girard (:BenWa)]

It would be nice-to-have if once we run out of pooled texture we can batch the allocations in a single IPC call. This would make a miss in this cache much cheaper.

Comment 3

[Chris Lord [:cwiiis]]

https://hg.mozilla.org/mozilla-central/rev/8394fed3332e