These changes remove unnecessary heap allocations in the XCOPY
READ/WRITE dispatch loop.
Synthetic benchmarks on my laptop using the libiscsi iscsi-dd utility
(--xcopy --max 1 --blocks 65535 src=dst) against a target backed by an
8G zram (DEBUG_KMEMLEAK=y) iblock backstore (avg across four runs) show:
before: 5.30845G/s
after: 5.99056G/s (approx. +12.8%)
Changes since v2:
- 5/5: incorporate Christoph's clean up suggestions
Changes since v1:
- drop RFC
- rework 3/5 and 5/5 following Christoph's feedback
Feedback appreciated.
Cheers, David
----------------------------------------------------------------
David Disseldorp (5):
scsi: target: use #def for xcopy descriptor len
scsi: target: drop xcopy DISK BLOCK LENGTH debug
scsi: target: avoid per-loop XCOPY buffer allocations
scsi: target: increase XCOPY I/O size
scsi: target: use the stack for XCOPY passthrough cmds
drivers/target/target_core_xcopy.c | 187 ++++++++++-------------------
drivers/target/target_core_xcopy.h | 9 +-
2 files changed, 64 insertions(+), 132 deletions(-)
