bcache: reduce gc latency by processing less nodes and sleep less time
[upstream commit: 70bc173ce06be90b026bb00ea175567c91f006e4]
When bcache device is busy for high I/O loads, there are two methods to
reduce the garbage collection latency,
- Process less nodes in eac loop of incremental garbage collection in
btree_gc_recurse().
- Sleep less time between two full garbage collection in
bch_btree_gc().
This patch introduces to hleper routines to provide different garbage
collection nodes number and sleep intervel time.
- btree_gc_min_nodes()
If there is no front end I/O, return 128 nodes to process in each
incremental loop, otherwise only 10 nodes are returned. Then front I/O
is able to access the btree earlier.
- btree_gc_sleep_ms()
If there is no synchronized wait for bucket allocation, sleep 100 ms
between two incremental GC loop. Othersize only sleep 10 ms before
incremental GC loop. Then a faster GC may provide available buckets
earlier, to avoid most of bcache working threads from being starved by
buckets allocation.
The idea is inspired by works from Mingzhe Zou and Robert Pang, but much
simpler and the expected behavior is more predictable.
BUG=b/466158659
TEST=presubmit
RELEASE_NOTE=Backported upstream commit to reduce bcache gc latency.
cos-patch: bug
Change-Id: I8e5a73e1e2bdb8d6bfb6077a59a6f8b72a9722cb
Signed-off-by: Coly Li <colyli@fnnas.com>
Signed-off-by: Robert Pang <robertpang@google.com>
Signed-off-by: Mingzhe Zou <mingzhe.zou@easystack.cn>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Reviewed-on: https://cos-review.googlesource.com/c/third_party/kernel/+/121941
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: Miri Amarilio <mirilio@google.com>
Reviewed-on: https://cos-review.googlesource.com/c/third_party/kernel/+/122026
3 files changed
