From 05cc7390735c49357b9ae67bf97f1c1579547f5b Mon Sep 17 00:00:00 2001 From: Yi Zou Date: Tue, 25 Aug 2009 13:59:03 -0700 Subject: [PATCH] [SCSI] fcoe: Add sysfs parameter to fcoe for minimum DDP read I/O size This adds fcoe_ddp_min as a module parameter for fcoe module to: /sys/module/fcoe/parameters/ddp_min It is observed that for some hardware, particularly Intel 82599, there is too much overhead in setting up context for direct data placement (DDP) read when the requested read I/O size is small. This is added as a module parameter for performance tuning and is set as 0 by default and user can change this based on their own hardware. Signed-off-by: Yi Zou Signed-off-by: Robert Love Signed-off-by: James Bottomley --- drivers/scsi/fcoe/fcoe.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-) diff --git a/drivers/scsi/fcoe/fcoe.c b/drivers/scsi/fcoe/fcoe.c index e32a0ed..a39d370 100644 --- a/drivers/scsi/fcoe/fcoe.c +++ b/drivers/scsi/fcoe/fcoe.c @@ -49,6 +49,12 @@ MODULE_AUTHOR("Open-FCoE.org"); MODULE_DESCRIPTION("FCoE"); MODULE_LICENSE("GPL v2"); +/* Performance tuning parameters for fcoe */ +static unsigned int fcoe_ddp_min; +module_param_named(ddp_min, fcoe_ddp_min, uint, S_IRUGO | S_IWUSR); +MODULE_PARM_DESC(ddp_min, "Minimum I/O size in bytes for " \ + "Direct Data Placement (DDP)."); + /* fcoe host list */ LIST_HEAD(fcoe_hostlist); DEFINE_RWLOCK(fcoe_hostlist_lock); @@ -414,7 +420,8 @@ static int fcoe_shost_config(struct fc_lport *lp, struct Scsi_Host *shost, */ bool fcoe_oem_match(struct fc_frame *fp) { - return fc_fcp_is_read(fr_fsp(fp)); + return fc_fcp_is_read(fr_fsp(fp)) && + (fr_fsp(fp)->data_len > fcoe_ddp_min); } /** -- 2.7.4