tree 844a174fc1140a03dc4f92ef21afc83642bc2e71
parent 5de8b416be37ee384d8f012c3f67ec99a9350e2a
author He Gao <hegao@google.com> 1750291279 +0000
committer Cloud Image Release <cloud-image-release@prod.google.com> 1750374183 -0700

bcache: process fewer btree nodes in incremental GC cycles

Current incremental GC processes a minimum of 100 btree nodes per cycle,
followed by a 100ms sleep. For NVMe cache devices, where the average node
processing time is ~1ms, this leads to front-side I/O latency potentially
reaching tens or hundreds of milliseconds during GC execution.

This commit resolves this latency issue by reducing the minimum node processing
count per cycle to 10 and the inter-cycle sleep duration to 10ms. It also
integrates a check of existing GC statistics to re-scale the number of nodes
processed per sleep interval when needed, ensuring GC finishes well before the
next GC is due.

BUG=b/425991664
TEST=presubmit
RELEASE_NOTE=Added kernel patch to address bcache latency.

cos-patch: bug
Change-Id: I6b7df47543f120a3d88c275a9384676a22d64ca7
Signed-off-by: Robert Pang <robertpang@google.com>
Reviewed-on: https://cos-review.googlesource.com/c/third_party/kernel/+/105438
Tested-by: Cusky Presubmit Bot <presubmit@cos-infra-prod.iam.gserviceaccount.com>
Main-Branch-Verified: Cusky Presubmit Bot <presubmit@cos-infra-prod.iam.gserviceaccount.com>
Reviewed-by: Robert Kolchmeyer <rkolchmeyer@google.com>
Reviewed-on: https://cos-review.googlesource.com/c/third_party/kernel/+/105408