Document metaslab_aliquot.

Signed-off-by: Etienne Dechamps <etienne@edechamps.fr>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>

diff --git a/module/zfs/metaslab.c b/module/zfs/metaslab.c
index 86bf3c1970fe3d2cac75c63b4cb5dd1025d813ad..15859908f00710d14cfefc90f55e92f7dcea5067 100644 (file)
--- a/module/zfs/metaslab.c
+++ b/module/zfs/metaslab.c
@@ -53,7 +53,14 @@
 #define        METASLAB_ACTIVE_MASK            \
        (METASLAB_WEIGHT_PRIMARY | METASLAB_WEIGHT_SECONDARY)
 
+/*
+ * Metaslab granularity, in bytes. This is roughly similar to what would be
+ * referred to as the "stripe size" in traditional RAID arrays. In normal
+ * operation, we will try to write this amount of data to a top-level vdev
+ * before moving on to the next one.
+ */
 uint64_t metaslab_aliquot = 512ULL << 10;
+
 uint64_t metaslab_gang_bang = SPA_MAXBLOCKSIZE + 1;    /* force gang blocks */
 
 /*