[Pvfs2-developers] BMI questions

[Scott Atchley]

On Nov 30, 2006, at 2:16 PM, Scott Atchley wrote:

>>> I am thinking about how to handle BMI_mx_memalloc(). I might be  
>>> able to assist the reg cache in MX if I do things a certain way.
>>
>> I mention this below, on the server we always call BMI_memalloc to  
>> allocate buffers and post them to BMI_post_send/BMI_post_recv.  On  
>> the client that's not always the case, the user buffer is usually  
>> passed directly to BMI_post_send/BMI_post_recv.  Would it help you  
>> to know in advance of the post (or all posts) what the maximum  
>> size of a buffer for BMI_post_send/BMI_post_recv is going to be?   
>> We might be able to add a BMI info option that other methods could  
>> ignore.  We do limit it, but its all above the BMI interface that  
>> this is done.
>
> Knowing the max size in advance helps iff the buffers are allocated  
> using BMI_memalloc(). If not, it does not matter.

I have changed my mind on this. ;-)

It would be helpful to have an info option to give the largest size.  
Even if I do not rely on MX's reg cache, being able to pre-allocate a  
small pool of buffers makes a huge difference in performance.

Scott