[PATCH RFC] increase ST_MAX_TAPES from 128 to 1024

[PATCH RFC] increase ST_MAX_TAPES from 128 to 1024

[Rob Evers]

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@redhat.com>
---
 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
 #define ST_MAX_TAPE_ENTRIES  (ST_MAX_TAPES << (ST_NBR_MODE_BITS + 1))
 
 /* The status related to each partition */
-- 
1.7.11.2

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

[Jeff Mahoney]

-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1

On 8/17/12 10:50 AM, 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.

I have the updated patch that fixes the tape symlink problem. I'll
send it out in a few.

- -Jeff

> Signed-off-by: Rob Evers <revers@redhat.com> --- 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 #define
> ST_MAX_TAPE_ENTRIES  (ST_MAX_TAPES << (ST_NBR_MODE_BITS + 1))
> 
> /* The status related to each partition */
> 


- -- 
Jeff Mahoney
SUSE Labs
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Re: [PATCH RFC] increase ST_MAX_TAPES from 128 to 1024

[James Bottomley]

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@redhat.com>
> ---
>  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

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

[Rob Evers]

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@redhat.com>
>> ---
>>   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

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

[Jeff Mahoney]

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@redhat.com>" <revers@redhat.com> 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@redhat.com>
>>> ---
>>>  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
> 
>