commit fba2f79d582ca4968af2d5ed82a02db0c46b1ccd
author Benoit Lize <lizeb@chromium.org> Wed Mar 15 09:03:43 2023
committer Chromium LUCI CQ <chromium-scoped@luci-project-accounts.iam.gserviceaccount.com> Wed Mar 15 09:03:43 2023
tree 801f8af22460cddb30815887f76186ac42b03c90
parent 15404e5bcdc6727f46dd21a44a45250546072274

[gpu] Add a feature to reclaim GPU memory in background

When a compositor frame is destroyed (for instance to cull old unlocked
frames on the browser side), the path is (browser) frame destruction ->
(GPU) Surface destruction -> (renderer) exported resources are returned
-> (renderer) SharedImages for tiles are destructed -> (GPU) SharedImage
destruction.

All these steps are asynchronous, but with the latest experiments all
enabled, do happen in background as well, as we've added the right
flushes of the various queues and command buffers.

However, with vulkan, the last step which is SharedImage destruction is
itself asynchronous. See DeleteGrBackendTexture() in skia_utils.cc. The
actual deletion is queued with
VulkanFenceHelper::EnqueueCleanupTaskForSubmittedWork(). But when no new
frames are being produced, the queue is never drained, meaning that
resources are never freed.

This CL adds a feature to ensure that the queue is emptied after all the
deferred requests are processed on a given GPU channel, but only when
the application is in background, as this is a heavyweight synchronizing
operation that could compromise performance otherwise (and it is not
believed to be necessary anyway when frames are being produced).

Locally, on a Pixel 6 Pro, when opening google.com/search?q=google,
scrolling a bit, and then going to background, this saves ~100MiB,
according to "adb shell dumpsys meminfo
org.chromium.chrome:privileged_process0".

For more details, see the linked bug, and
https://docs.google.com/document/d/1JnlFS1GcsXAk9_N80G1su89w_Vu_yvJHovRPIwO5zWU/edit#
(Google-internal).

Bug: 1424346
Change-Id: I88b2b3b2e4fbffe30d1554e46b9ad3adb8ae518f
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4335724
Commit-Queue: Benoit Lize <lizeb@chromium.org>
Reviewed-by: Vasiliy Telezhnikov <vasilyt@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1117414}