mirror_zfs/module
Alexander Motin edaec84225 Improve logging of 128KB writes
Before my ZIL space optimization few years ago 128KB writes were logged
as two 64KB+ records in two 128KB log blocks.  After that change it
became ~127KB+/1KB+ in two 128KB log blocks to free space in the second
block for another record.  Unfortunately in case of 128KB only writes,
when space in the second block remained unused, that change increased
write latency by unbalancing checksum computation and write times
between parallel threads.  It also didn't help with SLOG space
efficiency in that case.

This change introduces new 68KB log block size, used for both writes
below 67KB and 128KB-sharp writes.  Writes of 68-127KB are still using
one 128KB block to not increase processing overhead.  Writes above
131KB are still using full 128KB blocks, since possible saving there
is small.  Mixed loads will likely also fall back to previous 128KB,
since code uses maximum of the last 16 requested block sizes.

Reviewed-by: Matt Ahrens <matt@delphix.com>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by:  Alexander Motin <mav@FreeBSD.org>
Closes #9409
2020-01-22 13:49:04 -08:00
..
avl Fix typos in module/ 2020-01-22 13:48:59 -08:00
icp Linux 5.0 compat: SIMD compatibility 2020-01-22 13:49:01 -08:00
lua Fix typos in module/ 2020-01-22 13:48:59 -08:00
nvpair Fix typos in module/ 2020-01-22 13:48:59 -08:00
spl Update skc_obj_alloc for spl kmem caches that are backed by Linux 2020-01-22 13:49:03 -08:00
unicode Update build system and packaging 2018-05-29 16:00:33 -07:00
zcommon Fix pool creation with feature@allocation_classes disabled 2020-01-22 13:49:02 -08:00
zfs Improve logging of 128KB writes 2020-01-22 13:49:04 -08:00
.gitignore Prepare SPL repo to merge with ZFS repo 2018-05-29 14:51:39 -07:00
Makefile.in module/Makefile.in: don't run xargs if empty 2020-01-22 13:49:02 -08:00