[openib-general] A new simple ulp (SPTS)

[Talpey, Thomas]

At 12:43 PM 6/22/2005, Jeff Carr wrote:
>On 06/21/2005 12:50 PM, Roland Dreier wrote:
>
>> What happens if you try replacing the send_flags line with the one you
>> have commented out?
>> 
>> +	// send_wr.send_flags = IB_SEND_SIGNALED;
>
>Thanks, you are correct. IB_SEND_SIGNALED gives me the behavior I was
>expecting.

By the way, unsignaled sends can work very well indeed, but you have to be
sure to poll for completions at regular intervals. Basically, what you're doing
is ensuring that software (mthca) gets control from time to time, either via
an interrupt (signaled) or poll (unsignaled).

It's quite a challenge to get the polling right, but the reduction in interrupts
can be a win. The NFS/RDMA module does this, but it takes the approach
of "occasionally" posting a signaled send. The trick is getting the value of
"occasionally" right. :-)

Tom.