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authorJody McIntyre <scjody@steamballoon.com>2005-09-30 11:59:07 -0700
committerLinus Torvalds <torvalds@g5.osdl.org>2005-09-30 12:41:19 -0700
commit2bab359a5009f330b12a4ed09a57d3d2ac6b3483 (patch)
treedfce66056747d41b3594860a681ba53fb94fe798
parentabd559b1052e28d8b9c28aabde241f18fa89090b (diff)
downloadop-kernel-dev-2bab359a5009f330b12a4ed09a57d3d2ac6b3483.zip
op-kernel-dev-2bab359a5009f330b12a4ed09a57d3d2ac6b3483.tar.gz
[PATCH] sbp2: default to serialize_io=1
Set serialize_io=1 by default. This is safer and required by seemingly more and more hardware. It causes little or no performance loss for S400 devices. Performance of S800 1394b devices may drop by 25...30%. Therefore make the parameter's description and dmesg message clearer about performance impact. Update description of the max_speed parameter too. IEEE1394_SPEED_MAX is currently S800. Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de> Signed-off-by: Jody McIntyre <scjody@steamballoon.com> Cc: Ben Collins <bcollins@debian.org> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
-rw-r--r--drivers/ieee1394/sbp2.c11
1 files changed, 7 insertions, 4 deletions
diff --git a/drivers/ieee1394/sbp2.c b/drivers/ieee1394/sbp2.c
index 5d86b03..12cec7c 100644
--- a/drivers/ieee1394/sbp2.c
+++ b/drivers/ieee1394/sbp2.c
@@ -97,16 +97,18 @@ static char version[] __devinitdata =
*/
static int max_speed = IEEE1394_SPEED_MAX;
module_param(max_speed, int, 0644);
-MODULE_PARM_DESC(max_speed, "Force max speed (3 = 800mb, 2 = 400mb default, 1 = 200mb, 0 = 100mb)");
+MODULE_PARM_DESC(max_speed, "Force max speed (3 = 800mb, 2 = 400mb, 1 = 200mb, 0 = 100mb)");
/*
* Set serialize_io to 1 if you'd like only one scsi command sent
* down to us at a time (debugging). This might be necessary for very
* badly behaved sbp2 devices.
+ *
+ * TODO: Make this configurable per device.
*/
-static int serialize_io;
+static int serialize_io = 1;
module_param(serialize_io, int, 0444);
-MODULE_PARM_DESC(serialize_io, "Serialize all I/O coming down from the scsi drivers (default = 0)");
+MODULE_PARM_DESC(serialize_io, "Serialize I/O coming from scsi drivers (default = 1, faster = 0)");
/*
* Bump up max_sectors if you'd like to support very large sized
@@ -2857,7 +2859,8 @@ static int sbp2_module_init(void)
/* Module load debug option to force one command at a time (serializing I/O) */
if (serialize_io) {
- SBP2_ERR("Driver forced to serialize I/O (serialize_io = 1)");
+ SBP2_INFO("Driver forced to serialize I/O (serialize_io=1)");
+ SBP2_INFO("Try serialize_io=0 for better performance");
scsi_driver_template.can_queue = 1;
scsi_driver_template.cmd_per_lun = 1;
}
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