[roll] Roll fuchsia [kernel][futex] Improve futex performance of shared processes
Improve futex performance of shared processes by giving FutexContext's
HashTable more buckets.
We've observed that shared processes (think Starnix) tend to have
between 1000 and 2000 active futexes. Furthermore, products that use
shared processes tend to perform many futex operations per second.
Prior to this change, the hash table backing those active futexes had
only 37 buckets, which meant that the average futex operation had to
walk about 27 elements of a linked list (pointer chasing without cache
locality). By giving shared processes more buckets (1031) we bring
that number down to 1 or 2.
Memory usage of a group of shared processes increases by a small
amount (about 8KiB), but keep in mind that the increase is per group,
rather than per process since all members of a group share the same
FutexContext.
No impact to regular (non-shared) processes.
See https://fxbug.dev/382492390 for more details and analysis.
Original-Bug: 382492390
Original-Reviewed-on: https://fuchsia-review.googlesource.com/c/fuchsia/+/1105015
Original-Revision: dc99b5f3eeb40446d9f3f0731313896364b44993
GitOrigin-RevId: 9456a46c2b8831a47448406355f772f63d6b8003
Change-Id: I9f860acf78ed17624884e2a3bfaaf99c24f781fe
diff --git a/stem b/stem
index 6978fed..4a790d1 100644
--- a/stem
+++ b/stem
@@ -11,7 +11,7 @@
githooks="integration/git-hooks"
remote="https://fuchsia.googlesource.com/fuchsia"
gerrithost="https://fuchsia-review.googlesource.com"
- revision="670aea6b9b29e4718ca9d1dc67981db00d752fcc"
+ revision="dc99b5f3eeb40446d9f3f0731313896364b44993"
/>
</projects>
<hooks>
