Re: [patch 2/4] ibmvscsi.c: limit size of I/O requests

[Dave C Boutcher <sleddog@us.ibm.com>]

On Tue, Nov 30, 2004 at 08:54:58AM +0100, Jens Axboe wrote:
> On Mon, Nov 29 2004, Dave C Boutcher wrote:
> > Description: Limit the size of I/O requests sent by the 
> > ibmvscsi adapter.  With better I/O scheduling (and thus larger
> > requests) we were breaking some servers.
> 
> Nack, why can't you use /dev/block/xxx/queue/max_sectors_kb to control
> this?

The basic function of this patch is to set host->max_sectors based
on information from the SCSI target.

There is a default value because two of the existing target implementations
(there are three) don't set the value.

I confess to making the default value a module parameter because I
took a SWAG at the correct value.  I COULD remove the module
parameter part of this patch, though if someone actually cares enough
about performance to tweak it, modprobe.conf seems like a nice place to
set it.

-- 
Dave Boutcher