[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>
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@ -97,16 +97,18 @@ static char version[] __devinitdata =
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*/
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*/
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static int max_speed = IEEE1394_SPEED_MAX;
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static int max_speed = IEEE1394_SPEED_MAX;
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module_param(max_speed, int, 0644);
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module_param(max_speed, int, 0644);
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MODULE_PARM_DESC(max_speed, "Force max speed (3 = 800mb, 2 = 400mb default, 1 = 200mb, 0 = 100mb)");
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MODULE_PARM_DESC(max_speed, "Force max speed (3 = 800mb, 2 = 400mb, 1 = 200mb, 0 = 100mb)");
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/*
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/*
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* Set serialize_io to 1 if you'd like only one scsi command sent
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* Set serialize_io to 1 if you'd like only one scsi command sent
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* down to us at a time (debugging). This might be necessary for very
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* down to us at a time (debugging). This might be necessary for very
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* badly behaved sbp2 devices.
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* badly behaved sbp2 devices.
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*
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* TODO: Make this configurable per device.
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*/
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*/
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static int serialize_io;
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static int serialize_io = 1;
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module_param(serialize_io, int, 0444);
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module_param(serialize_io, int, 0444);
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MODULE_PARM_DESC(serialize_io, "Serialize all I/O coming down from the scsi drivers (default = 0)");
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MODULE_PARM_DESC(serialize_io, "Serialize I/O coming from scsi drivers (default = 1, faster = 0)");
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/*
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/*
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* Bump up max_sectors if you'd like to support very large sized
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* Bump up max_sectors if you'd like to support very large sized
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@ -2857,7 +2859,8 @@ static int sbp2_module_init(void)
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/* Module load debug option to force one command at a time (serializing I/O) */
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/* Module load debug option to force one command at a time (serializing I/O) */
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if (serialize_io) {
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if (serialize_io) {
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SBP2_ERR("Driver forced to serialize I/O (serialize_io = 1)");
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SBP2_INFO("Driver forced to serialize I/O (serialize_io=1)");
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SBP2_INFO("Try serialize_io=0 for better performance");
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scsi_driver_template.can_queue = 1;
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scsi_driver_template.can_queue = 1;
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scsi_driver_template.cmd_per_lun = 1;
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scsi_driver_template.cmd_per_lun = 1;
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}
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}
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