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Re: [remote protocol] support for disabling packet acknowledgement
- From: Paul Koning <Paul_Koning at dell dot com>
- To: sandra at codesourcery dot com
- Cc: gdb at sourceware dot org, gdb-patches at sourceware dot org, pedro at codesourcery dot com
- Date: Thu, 10 Jul 2008 15:09:18 -0400
- Subject: Re: [remote protocol] support for disabling packet acknowledgement
- References: <48765B8A.6080805@codesourcery.com>
>>>>> "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