Commit 8f6fd19f authored by Guennadi Liakhovetski's avatar Guennadi Liakhovetski Committed by James Bottomley
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[SCSI] enable clustering for tmscsim 



following an email from John Adams <johna@onevista.com> to me with a patch
to enable tmscsim to use blocks up to 1MB and a discussion on linux-scsi,
below is a patch to enable clustering for tmscsim. I made it switchable
with a module parameter, with default "enable" - in case somebody gets
problems with it. Unfortunately, I was not able to check if this alone
lets you use any bigger blocks with a tape, as my tape seems to only
support 1 block size - only "mt setblk 1" is successful, any other value
fails. OTOH, testing on a P-133 showed that enabling clustering alone
improves throughput by 10% and reduces CPU load by another 10%, so, seems
a worthy thing to do. As for setting max_sectors, that might become a
separate patch...

Signed-off-by: default avatarJames Bottomley <James.Bottomley@SteelEye.com>
parent f70cfa9b

drivers/scsi/tmscsim.c

+11 −1
Original line number Diff line number Diff line
@@ -279,6 +279,10 @@ static void dc390_ResetDevParam(struct dc390_acb* pACB); 
static u32	dc390_laststatus = 0;

static u8	dc390_adapterCnt = 0;



static int disable_clustering;

module_param(disable_clustering, int, S_IRUGO);

MODULE_PARM_DESC(disable_clustering, "If you experience problems with your devices, try setting to 1");



/* Startup values, to be overriden on the commandline */

static int tmscsim[] = {-2, -2, -2, -2, -2, -2};
@@ -2299,7 +2303,7 @@ static struct scsi_host_template driver_template = { 
	.this_id		= 7,

	.sg_tablesize		= SG_ALL,

	.cmd_per_lun		= 1,

	.use_clustering		= DISABLE_CLUSTERING,

	.use_clustering		= ENABLE_CLUSTERING,

};



/***********************************************************************
@@ -2525,6 +2529,8 @@ static int __devinit dc390_probe_one(struct pci_dev *pdev, 
	pci_set_master(pdev);



	error = -ENOMEM;

	if (disable_clustering)

		driver_template.use_clustering = DISABLE_CLUSTERING;

	shost = scsi_host_alloc(&driver_template, sizeof(struct dc390_acb));

	if (!shost)

		goto out_disable_device;
@@ -2660,6 +2666,10 @@ static struct pci_driver dc390_driver = { 


static int __init dc390_module_init(void)

{

	if (!disable_clustering)

		printk(KERN_INFO "DC390: clustering now enabled by default. If you get problems load\n"

		       "\twith \"disable_clustering=1\" and report to maintainers\n");



	if (tmscsim[0] == -1 || tmscsim[0] > 15) {

		tmscsim[0] = 7;

		tmscsim[1] = 4;

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