Re: [PATCH RFC] increase ST_MAX_TAPES from 128 to 1024

["Jeff Mahoney" <jeffm@xxxxxxxx>]

The preallocation of cdevs is also addressed in my patch set. I'll send it out as soon as I'm at my notebook again.

-Jeff

--
Jeff Mahoney
(apologies for the top post -- from my mobile)

On Aug 17, 2012, at 4:58 PM, "Rob Evers <revers@xxxxxxxxxx>" <revers@xxxxxxxxxx> wrote:

> On 08/17/2012 11:37 AM, James Bottomley wrote:
>> On Fri, 2012-08-17 at 10:50 -0400, Rob Evers wrote:
>>> Wondering if this would be an acceptable interim solution
>>> to increasing the limit on the number of tape drives
>>> while http://marc.info/?l=linux-scsi&m=134212042809524&w=2
>>> gets sorted out.
>>> 
>>> Signed-off-by: Rob Evers<revers@xxxxxxxxxx>
>>> ---
>>>  drivers/scsi/st.h | 2 +-
>>>  1 file changed, 1 insertion(+), 1 deletion(-)
>>> 
>>> diff --git a/drivers/scsi/st.h b/drivers/scsi/st.h
>>> index b548923..408d24f 100644
>>> --- a/drivers/scsi/st.h
>>> +++ b/drivers/scsi/st.h
>>> @@ -76,7 +76,7 @@ struct st_modedef {
>>>  #define ST_MODE_SHIFT (7 - ST_NBR_MODE_BITS)
>>>  #define ST_MODE_MASK ((ST_NBR_MODES - 1)<<  ST_MODE_SHIFT)
>>> 
>>> -#define ST_MAX_TAPES 128
>>> +#define ST_MAX_TAPES 1024
>> This is going to cause an order 2 GFP_ATOMIC allocation (on 64 bit
>> platforms) for the contiguous scsi_tapes array ... if large numbers of
>> tapes are genuinely required, shouldn't we fix this first and then
>> expand the number quite a bit more?
>> 
>> James
>> 
> 
> Pre allocation of cdevs during init time needs addressing as well
> to increase ST_MAX_TAPES quite a bit more, right?
> 
> Would leaving out Lee's sysfs updates out be ok, if ST_MAX_TAPES were
> significantly increased?
> 
> Rob
> 
> 

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