Re: Performance figure for sx8 driver

[Jeff Garzik <jgarzik@pobox.com>]

kallol@nucleodyne.com wrote:
> Does anyone have performace figure for sx8 driver which is for promise SATAII150
> 8 port PCI-X adapter?
> 
> Someone reports that on a platform with sx8 driver, multiple hdparms on
> different disks those are connected to the same adapter (there are 8 ports) can
> not get more than 45MB/sec in total, whereas a SCSI based driver for the same
> adapter gets around 150MB/sec.
> 
> Any comment on this?

Known.  Early firmwares for SX8 had problems that forced the driver to 
limit the number of outstanding requests, for all ports, to _one_.

Later firmwares have fixed this, but the driver has not been updated to 
detect newer(fixed) firmwares.

You may update drivers/block/sx8.c as such:

- CARM_MAX_Q              = 1,               /* one command at a time */
+ CARM_MAX_Q              = 30,              /* 30 commands at a time */

if you have a newer firmware, to obtain much better performance.

	Jeff