[pnfs] [PATCH] Increase maximum buffer size for layouts to 4 KB

[Dean Hildebrand]

Benny Halevy wrote:
> William A. (Andy) Adamson wrote:
>   
>> hi benny
>>
>> should be ok.
>> are you expecting to have a large number of 4KB layouts? are you 
>> combining a bunch of layout ranges in the 4KB layout return?
>>     
> not necessarily...
> we just have big data structures.
> are we going to keep this static?
> If so I will check what;s the largest size we can anticipate
>
>
>   
The patch below definitely can't go in as is since 4kb layouts will need 
to come off the heap.  I'm assuming you are using a 64 bit machine or 
8kb stacksize to make this patch work.

Do we want to
a) malloc 4kb on every layoutget
b) use a layout buffer pool
c) malloc a buffer on every layoutget, but retrieve the size of the 
buffer (the max layout size) from the layout driver
d) other ways?

Dean

>   
>> -->Andy
>>
>> On 11/28/06, *Benny Halevy* <bhalevy at panasas.com 
>> <mailto:bhalevy at panasas.com>> wrote:
>>
>>     We need a bigger buffer size for our layouts.  Since we're
>>     still using a statically sized buffer, is it ok with everybody
>>     to increase its size to 4 KB as in the patch below?
>>
>>     Benny
>>
>>     Increase maximum buffer size for layouts to 4 KB.
>>
>>     Signed-off-by: Benny Halevy bhalevy at panasas.com
>>     <mailto:bhalevy at panasas.com>
>>
>>     ==== //depot/pub/pnfs/include/linux/pnfs_xdr.h#1 -
>>     /home/bhalevy/p4.local/pub-pnfs/include/linux/pnfs_xdr.h ====
>>     diff -Npu /tmp/tmp.12239.0
>>     /home/bhalevy/p4.local/pub-pnfs/include/linux/pnfs_xdr.h -L
>>     a/include/linux/pnfs_xdr.h -L b/include/linux/pnfs_xdr.h
>>     --- a/include/linux/pnfs_xdr.h
>>     +++ b/include/linux/pnfs_xdr.h
>>     @@ -14,7 +14,7 @@
>>
>>       #include <linux/nfs4.h>
>>
>>     -#define PNFS_LAYOUT_MAXSIZE 1024
>>     +#define PNFS_LAYOUT_MAXSIZE 4096
>>       #define PNFS_MAX_NUM_LAYOUT_TYPES 2
>>
>>       enum layoutreturn_type {
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>>
>>
>>     
>
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-- 
Dean Hildebrand
Ph.D. Candidate
University of Michigan