[PATCH] sg driver for large page_size, lk 2.6.18

[PATCH] sg driver for large page_size, lk 2.6.18

[Douglas Gilbert]

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This sg driver patch addresses the problem with larger
page sizes reported by Brian King in this post:
http://marc.theaimsgroup.com/?l=linux-scsi&m=115867718623631&w=2
Some other related matters are also addressed. Some of these
prevent oopses when the SG_SCATTER_SZ or scatter_elem_sz are
set to inappropriate values.

The scatter_elem_sz has been tested up to 4 MB which should
make the largest data transfer with one SCSI command, 32 MB
less one block, achievable with a relatively small number
of elements in the scatter gather list.

For consideration in lk 2.6.19 . The patch is against lk 2.6.18 .

  ChangeLog:
    - add scatter_elem_sz boot time parameter and sysfs module
      parameter that is initialized to SG_SCATTER_SZ
    - the driver will then adjust scatter_elem_sz to be the
      max(given(scatter_elem_sz), PAGE_SIZE)
      It will also round it up, if necessary, to be a power
      of two
    - clean up sg.h header, correct bad urls and some statements
      that are no longer valid
    - make the def_reserved_size sysfs module attribute writable

Signed-off-by: Douglas Gilbert <dougg@torque.net>

Doug Gilbert


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Re: [PATCH] sg driver for large page_size, lk 2.6.18

[Brian King]

Douglas Gilbert wrote:
> This sg driver patch addresses the problem with larger
> page sizes reported by Brian King in this post:
> http://marc.theaimsgroup.com/?l=linux-scsi&m=115867718623631&w=2

This fixes the oops I was seeing on PPC64 with 64k pages
enabled.

Brian


> Some other related matters are also addressed. Some of these
> prevent oopses when the SG_SCATTER_SZ or scatter_elem_sz are
> set to inappropriate values.
> 
> The scatter_elem_sz has been tested up to 4 MB which should
> make the largest data transfer with one SCSI command, 32 MB
> less one block, achievable with a relatively small number
> of elements in the scatter gather list.
> 
> For consideration in lk 2.6.19 . The patch is against lk 2.6.18 .
> 
>   ChangeLog:
>     - add scatter_elem_sz boot time parameter and sysfs module
>       parameter that is initialized to SG_SCATTER_SZ
>     - the driver will then adjust scatter_elem_sz to be the
>       max(given(scatter_elem_sz), PAGE_SIZE)
>       It will also round it up, if necessary, to be a power
>       of two
>     - clean up sg.h header, correct bad urls and some statements
>       that are no longer valid
>     - make the def_reserved_size sysfs module attribute writable
> 
> Signed-off-by: Douglas Gilbert <dougg@torque.net>
> 
> Doug Gilbert
> 


-- 
Brian King
eServer Storage I/O
IBM Linux Technology Center