Hi
following an email from John Adams <johna@xxxxxxxxxxxx> 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...
Thanks
Guennadi
---
Guennadi Liakhovetski
Signed-off-by: Guennadi Liakhovetski <g.liakhovetski@xxxxxx>
Enable clustering on tmscsim by default, but allow switching it off with a
module parameter. In a test it increased throughput by 10% and reduced CPU
load by another 10%.
diff -u -p a/drivers/scsi/tmscsim.c b/drivers/scsi/tmscsim.c
--- a/drivers/scsi/tmscsim.c 8 Feb 2006 23:08:48 -0000
+++ b/drivers/scsi/tmscsim.c 30 Sep 2006 19:10:53 -0000
@@ -280,6 +280,10 @@ static void dc390_ResetDevParam(struct d
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};
@@ -2300,7 +2304,7 @@ static struct scsi_host_template driver_
.this_id = 7,
.sg_tablesize = SG_ALL,
.cmd_per_lun = 1,
- .use_clustering = DISABLE_CLUSTERING,
+ .use_clustering = ENABLE_CLUSTERING,
};
/***********************************************************************
@@ -2526,6 +2530,8 @@ static int __devinit dc390_probe_one(str
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;
@@ -2661,6 +2667,10 @@ 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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