From: Jody McIntyre Date: Fri, 30 Sep 2005 18:59:07 +0000 (-0700) Subject: [PATCH] sbp2: default to serialize_io=1 X-Git-Tag: v2.6.14-rc3~13 X-Git-Url: http://pilppa.com/gitweb/?a=commitdiff_plain;h=2bab359a5009f330b12a4ed09a57d3d2ac6b3483;p=linux-2.6-omap-h63xx.git [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 Signed-off-by: Jody McIntyre Cc: Ben Collins Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- diff --git a/drivers/ieee1394/sbp2.c b/drivers/ieee1394/sbp2.c index 5d86b03979e..12cec7c4a34 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; }