[7138] in linux-scsi channel archive
Re: scsi driver transfer size and sync mode
daemon@ATHENA.MIT.EDU (Marc SCHAEFER)
Sat Sep 4 03:51:16 1999
To: linux-scsi@vger.rutgers.edu
From: Marc SCHAEFER <schaefer@alphanet.ch>
Date: 4 Sep 1999 09:48:49 +0200
Tony Chung <chungto@ampex.com> wrote:
> > Not true. My driver is happy to use S/G segments far larger than 4K in size
> > as long as the segments are physically contiguous. Check the SCSI clustering
[ ... ]
> Thank you for awakening me! I can now get sustained transfer rate of close to 15MB/s
> after only adding these two lines in /etc/conf.modules:
> keep
> options st buffer_kbs=1024 max_sg_segs=128
The risk is there is no guarantee that at time of allocation you can
find enough contiguous 4k buffers. If the st driver allocates the DMA
buffer at boot time, it is going to be always fine. If it's modularized
or if it allocates at open() time, you will have cases where performance
will degrade over time.
> I think currently the st driver is capable to allocate 1024K contingous physical
To my knowledge, this is impossible, except with luck or boot-time
reservation.
-
To unsubscribe from this list: send the line "unsubscribe linux-scsi" in
the body of a message to majordomo@vger.rutgers.edu
