Re: [PATCH] [SCSI] sym53c8xx: increase sg_tablesize for larger data transfers

[Tony Battersby <tonyb@cybernetics.com>]

James Bottomley wrote:
> On Thu, 2007-11-15 at 10:06 -0500, Tony Battersby wrote:
>   
>> This patch increases the sg_tablesize for sym53c8xx from 96 to 128,
>> which enables commands to transfer larger amounts of data (e.g. 512 KB
>> instead of 384 KB, assuming 4 KB non-adjacent pages).
>>
>> In the current design of sym53c8xx, SYM_CONF_MAX_SG must be set low
>> enough so that (sym_fw1.a_size <= PAGE_SIZE) && (sym_fw2.a_size <=
>> PAGE_SIZE).  With SYM_CONF_MAX_SG == 128, sym_fw1.a_size == 3940 and
>> sym_fw2.a_size == 3576 (plus or minus a few bytes depending on other
>> configuration options).  The a_size values increase by 16 for every
>> additional sg vector, so SYM_CONF_MAX_SG cannot be set much higher than
>> 128 without making more intrusive changes.
>>     
>
> This has been suggested before.  I thought the problem was there were
> some cards of the 875 ilk that choke on a sg table larger than 96?  If I
> recall the conversation correctly, the claim was made, but no-one
> managed to turn up the errata that showed it.
>
> James
>
>
>   
I will try to get ahold of some 875's to test.

Tony