commit 34cdc74c114cd7473b38d4ce666eeee6637f6067
author Steinar H. Gunderson <sesse@chromium.org> Mon Sep 26 18:05:58 2022
committer Chromium LUCI CQ <chromium-scoped@luci-project-accounts.iam.gserviceaccount.com> Mon Sep 26 18:05:58 2022
tree de531af59c9b4a02d6fefde99022b95a5b17c609
parent 426e80278328b18ddd5197a899189c6cf4badc85

Do not store self-invalidation sets for classes.

This saves a lot of memory for sites with lots of simple class
selectors, at the cost of self-invalidation for any element that
gets a class added or removed. Note in particular that adding or
removing a style sheet then self-invalidates all DOM nodes that
have a class attribute.

We add a Bloom filter to mitigate this (inserting each such class
name into the Bloom filter), which should be 95% effective at
rejecting the spurious self-invalidations whenever we're below ~2000
such sets, but it will deteriorate if we have a lot of them.
To investigate this on the real web, we put this behind a new Finch
experiment called InvalidationSetClassBloomFilter, since it's
potentially a CPU/RAM tradeoff and we'd like to see exactly how
good/bad it is.

Style perftest, PartitionAlloc memory:

  ECommerce       1388 →  1371 kB (  -17 kB)
  Encyclopedia    6403 →  6259 kB ( -144 kB)
  Extension       6145 →  6141 kB (   -4 kB)
  News            3866 →  3803 kB (  -63 kB)
  Search          1880 →  1763 kB ( -117 kB)
  Social1         5606 →  4589 kB (-1017 kB)
  Social2          488 →   453 kB (  -35 kB)
  Sports          3713 →  3325 kB ( -388 kB)
  Video          11191 → 11058 kB ( -133 kB)

Change-Id: Idf811ae45a5425f6059624589f289b0f4800c1d3
Bug: 1368064
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3913591
Reviewed-by: Anders Hartvoll Ruud <andruud@chromium.org>
Commit-Queue: Steinar H Gunderson <sesse@chromium.org>
Reviewed-by: Kentaro Hara <haraken@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1051296}