zvol_os.c: Increase optimal IO size

ixhamza · ixhamza · commit c25ec96fcb8b · 2024-11-13T22:03:45.000+05:00
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 VDIv2 workloads.

Signed-off-by: Ameer Hamza &lt;ahamza@ixsystems.com&gt;
diff --git a/module/os/linux/zfs/zvol_os.c b/module/os/linux/zfs/zvol_os.c
@@ -1193,7 +1193,7 @@ 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 =

Original file line number	Diff line number	Diff line change
`@@ -1193,7 +1193,7 @@ zvol_queue_limits_init(zvol_queue_limits_t limits, zvol_state_t zv,`
`1193`	`1193`	`limits->zql_max_segment_size = UINT_MAX;`
`1194`	`1194`	`}`
`1195`	`1195`
`1196`		`- limits->zql_io_opt = zv->zv_volblocksize;`
	`1196`	`+ limits->zql_io_opt = DMU_MAX_ACCESS/2;`
`1197`	`1197`
`1198`	`1198`	`limits->zql_physical_block_size = zv->zv_volblocksize;`
`1199`	`1199`	`limits->zql_max_discard_sectors =`