zvol_os.c: Increase optimal IO size

Since zvol read and write can process up to (DMU_MAX_ACCESS / 2) bytes in a single operation, the current optimal I/O size is too low. SCST directly reports this value as the optimal transfer length for the target SCSI device. Increasing it from the previous volblocksize results in performance improvement for large block parallel I/O workloads. Reviewed-by: Brian Behlendorf <[email protected]> Reviewed-by: Alexander Motin <[email protected]> Signed-off-by: Ameer Hamza <[email protected]> Closes openzfs#16750
behlendorf · Nov 15, 2024 · 4c9f2ce · 4c9f2ce
1 parent ee3677d
commit 4c9f2ce
Showing 1 changed file with 1 addition and 1 deletion.
diff --git a/module/os/linux/zfs/zvol_os.c b/module/os/linux/zfs/zvol_os.c
@@ -1176,7 +1176,7 @@ zvol_queue_limits_init(zvol_queue_limits_t *limits, zvol_state_t *zv,
 		limits->zql_max_segment_size = UINT_MAX;
 	}
 
-	limits->zql_io_opt = zv->zv_volblocksize;
+	limits->zql_io_opt = DMU_MAX_ACCESS / 2;
 
 	limits->zql_physical_block_size = zv->zv_volblocksize;
 	limits->zql_max_discard_sectors =