Etienne Dechamps 5d7a86d114 Use the slog even with logbias=throughput. ... In the current code, logbias=throughput implies the following: 1) All synchronous writes are logged in indirect mode. 2) The slog is not used. (1) makes sense because it avoids writing the data twice, which is obviously a good thing when the user wants maximum pool throughput. (2), however, is a surprising decision. Considering all writes are indirect, the log record doesn't contain the actual data, only pointers to DMU blocks. As a result, log records written in logbias=throughput mode are quite small, and as such, it doesn't make any sense to write them to the main pool since slogs are usually optimized for small synchronous writes. In fact, the current behavior is actually harmful for performance, because log blocks and data blocks from dmu_sync() seldom have the same allocation size and as a result are usually allocated from different metaslabs. This means that if a spindle has to write both log blocks and DMU blocks (which is likely to happen under heavy load), it will have to seek between the two. Allocating the log blocks from the slog pool instead of the main pool avoids these unnecessary seeks. This commit makes ZFS use the slog on datasets with logbias=throughput. Real-life performance testing shows a 50% synchronous write performance increase with some large commit sizes, and no negative effect in other cases. Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov> Issue #1013		2012-10-17 08:56:46 -07:00
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avl	Add script for builtin module building.	2012-07-26 13:45:09 -07:00
nvpair	Add script for builtin module building.	2012-07-26 13:45:09 -07:00
unicode	Add script for builtin module building.	2012-07-26 13:45:09 -07:00
zcommon	Illumos #1948: zpool list should show more detailed pool info	2012-09-19 13:39:05 -07:00
zfs	Use the slog even with logbias=throughput.	2012-10-17 08:56:46 -07:00
zpios	Add script for builtin module building.	2012-07-26 13:45:09 -07:00
.gitignore	Add .gitignore files to exclude build products	2010-01-08 11:35:17 -08:00
Makefile.in	Add script for builtin module building.	2012-07-26 13:45:09 -07:00