They're all public because it's a struct, so there's no need to make
them explicit. clang-14 deprecates these.
Signed-off-by: Zygo Blaxell <bees@furryterror.org>
Add some conditionally-compiled debug code, including an in-memory log
of what ExtentWalker does. Dump that log on exceptions.
If we loop too many times in a debug build, kill the process so we can
stack trace. In non-debug builds just throw a normal exception.
Grow the step size instead of shrinking it, to reduce the number of
binary search iterations.
Prevent a bug where the step size bottoms out before positioning the
target extent in the middle of the result vector.
Use the first extent for "first_extent", instead of the 3rd.
Get rid of some redundant checks.
Signed-off-by: Zygo Blaxell <bees@furryterror.org>
ExtentWalker doesn't gain significant benefits from caching, and the
extra SEARCH_V2 ioctls were blamed for a 33% kernel CPU overhead by perf.
Reduce the number of extents to 16 in lieu of fixing the caching.
This gives a significant speed boost on CPU-bound workloads compared
to the original 1024--almost 40% faster on a single SSD with a filesystem
consisting of raw VM images mounted with compress=zstd.
This also seems to reduce LOGICAL_INO overhead. Perhaps SEARCH_V2 and
LOGICAL_INO were trying to lock the same extents, and interfering with
each other?
Signed-off-by: Zygo Blaxell <bees@furryterror.org>
Perf was blaming more than 50% of cycles on TREE_SEARCH_V2. strace
showed 4 TREE_SEARCH_V2 calls for every pread in grow_backward().
Fix by increasing the extent fetch batch size so it is more likely
to include the desired items in the first fetch attempt.
This removes TREE_SEARCH_V2 from the top 10 list of cycle consumers.
Signed-off-by: Zygo Blaxell <bees@furryterror.org>
