Re: 3ware queue depth [was: Re: HIGHMEM4G config for 1GB RAM ondesktop?]

From: Miquel van Smoorenburg
Date: Wed Sep 01 2004 - 06:10:14 EST

On 2004.09.01 12:09, Christoph Hellwig wrote:
On Wed, Sep 01, 2004 at 09:58:55AM +0000, Miquel van Smoorenburg wrote:
> On 2004.09.01 11:33, Matt Heler wrote:
> >
> > I have a 3ware 7000-2 card. And I noticed the same problem. > > > > Actually what I just did now was change the max luns from 254 to 64. > > Recompiled and booted up. This seems to fix all my problems, and the speed > > seems to be quite faster then before.
> > Yes, that is because the queue_depth parameter gets set from
> TW_MAX_CMDS_PER_LUN by the 3w-xxxx.c driver ...
> > I found the 3ware patch. The patch below makes the queue depth
> an optional module parameter, makes sure that the initial
> nr_requests is twice the size of the queue_depth, and
> makes queue_depth writable for the 3ware driver.

- the writeable queue_depth sysfs attr is fine,
- the reverse_scan option is vetoed because it can't be supported when
the driver will be converted to the pci_driver interface (soon)

Sure. That was more an experiment (the BIOS of the Tyan mobo I use
detects PCI cards in the reverse order from the kernel ...)

- I'm not so sure about the module parameter, what's the problem of beeing
able to only change the queue depth once sysfs is mounted?

Nothing much, I guess. Just ease of use, or "there's more than one
way to do it". Hey wait, that tunable is already a module parameter
in at least 2.6.9-rc1, only there it's called 'cmds_per_lun'.
Ofcourse cmds_per_lun and queue_depth are the same.

Anyway here's the minimal patch against 2.6.9-rc1

[PATCH] 3w-xxxx.c queue depth

make 3w-xxxx.c queue_depth sysfs parameter writable, adjust initial
queue nr_requests to 2*queue_depth

Signed-off-by: Miquel van Smoorenburg <miquels@xxxxxxxxxx>

--- linux-2.6.9-rc1/drivers/scsi/3w-xxxx.c.orig 2004-08-17 22:07:49.000000000 +0200
+++ linux-2.6.9-rc1/drivers/scsi/3w-xxxx.c 2004-09-01 13:07:32.000000000 +0200
@@ -184,6 +184,8 @@
1.26.00.039 - Fix bug in tw_chrdev_ioctl() polling code.
Fix data_buffer_length usage in tw_chrdev_ioctl().
Update contact information.
+ 1.02.00.XXX - Miquel van Smoorenburg - make queue_depth sysfs parameter
+ writable, adjust initial queue nr_requests to 2*queue_depth
*/

#include <linux/module.h>
@@ -3388,8 +3390,6 @@
{
int max_cmds;

- dprintk(KERN_WARNING "3w-xxxx: tw_slave_configure()\n");
-
if (cmds_per_lun) {
max_cmds = cmds_per_lun;
if (max_cmds > TW_MAX_CMDS_PER_LUN)
@@ -3399,6 +3399,10 @@
}
scsi_adjust_queue_depth(SDptr, MSG_ORDERED_TAG, max_cmds);

+ /* make sure blockdev queue depth is at least 2 * scsi depth */
+ if (SDptr->request_queue->nr_requests < 2 * max_cmds)
+ SDptr->request_queue->nr_requests = 2 * max_cmds;
+
return 0;
} /* End tw_slave_configure() */

@@ -3482,6 +3486,34 @@
outl(control_reg_value, control_reg_addr);
} /* End tw_unmask_command_interrupt() */

+static ssize_t
+tw_store_queue_depth(struct device *dev, const char *buf, size_t count)
+{
+ int depth;
+
+ struct scsi_device *SDp = to_scsi_device(dev);
+ if (sscanf(buf, "%d", &depth) != 1)
+ return -EINVAL;
+ if (depth < 1 || depth > TW_MAX_CMDS_PER_LUN)
+ return -EINVAL;
+ scsi_adjust_queue_depth(SDp, MSG_ORDERED_TAG, depth);
+
+ return count;
+}
+
+static struct device_attribute tw_queue_depth_attr = {
+ .attr = {
+ .name = "queue_depth",
+ .mode = S_IWUSR,
+ },
+ .store = tw_store_queue_depth,
+};
+
+static struct device_attribute *tw_dev_attrs[] = {
+ &tw_queue_depth_attr,
+ NULL,
+};
+
static Scsi_Host_Template driver_template = {
.proc_name = "3w-xxxx",
.proc_info = tw_scsi_proc_info,
@@ -3499,6 +3531,7 @@
.max_sectors = TW_MAX_SECTORS,
.cmd_per_lun = TW_MAX_CMDS_PER_LUN,
.use_clustering = ENABLE_CLUSTERING,
+ .sdev_attrs = tw_dev_attrs,
.emulated = 1
};
#include "scsi_module.c"


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