[remote protocol] support for disabling packet acknowledgement

Paul Koning Paul_Koning@dell.com
Thu Jul 10 19:09:00 GMT 2008


>>>>> "Sandra" == Sandra Loosemore <sandra@codesourcery.com> writes:

 Sandra> Paul Koning wrote:
 >> I'm not sure this is a good idea.
 >> 
 >> For one thing, if you want to work on performance, there are much
 >> more dramatic changes to the protocol that could be done that
 >> would help much more.  I can't believe that the cost of acks is
 >> significant compared to all the other bottlenecks.

 Sandra> You'll note the documentation says turning off acks may be
 Sandra> desirable to reduce communication overhead *or* "for other
 Sandra> reasons".  In fact, it is the "other reasons" that motivated
 Sandra> this patch.  We are working on designing the extensions to
 Sandra> the remote protocol to support nonstop mode, and we realized
 Sandra> that we simply cannot do it in combination with using +/-
 Sandra> acks on the asynchronous responses.  If we need a reliable
 Sandra> transport layer to support nonstop mode, we might as well
 Sandra> turn the acks off completely instead of dealing with the
 Sandra> extra complexity of trying to design the nonstop protocol
 Sandra> around them.

Ok, so does that mean the nonstop mode features won't work unless the
remote protocol is layered on TCP?  Given that a lot of the time the
remote link is simply a UART serial link, is there an issue here?  

       paul



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