Re: 3w-9xxx status in kernel

[Miquel van Smoorenburg]

In article <e2558p$o5f$2@xxxxxxxxxxxxx>,
Martin Honermeyer  <maze@xxxxxxxxxxxxxxxxx> wrote:
>Hi,
>
>same problem over here. Why does the newest kernel contain an old version of
>the 3w-9xxx driver? 
>
>We are having performance problems using a 9550SX controller. Read
>throughput (measured with hdparm) is worse than on a Desktop system. We are
>considering trying to replace it with the newest driver from 3ware.com.

The default settings for the 3w9xxx cards suck.

You need to make sure that the nr_requests (kernel request queue)
is at least twice the size of queue_depth (hardware requests queue).
Also the deadline or cfq i/o schedulers work a bit better for
database-like workloads.

Try something like this, replacing sda with the device name
of your 3ware controller.

	# Limit queue depth somewhat
	echo 128 > /sys/block/sda/device/queue_depth

	# Increase nr_requests
	echo 256 > /sys/block/sda/queue/nr_requests

	# Don't use as for database-like loads
	echo deadline > /sys/block/sda/queue/scheduler

CFQ seems to like larger nr_requests, so if you use CFQ, try 254
(maximum hardware size) for queue_depth and 512 or 1024 for nr_requests.

Oh, remember, if you have just created a RAID array on
the disks, wait with testing until the whole array has been
rebuild..

Mike.

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