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From: | Dirk Ziegelmeier |
Subject: | Re: [lwip-devel] [bug #49218] pbuf_clen() overflow as a result of tcp_write concatenation |
Date: | Fri, 30 Sep 2016 12:54:52 +0200 |
Follow-up Comment #6, bug #49218 (project lwip):
> And that was my point: I don't expect you have a scatter-gather-MAC that
supports TX frames with that many chunks. Being like that, you probably end up
copying all bytes per CPU anyway. Thus, I don't see the advantage of doing it
with ref pbufs. On the contrary, it's probably less performant.
That is correct, and that is the other side of why I think the ideal solution
is to merge multiple consecutive buffer-local references. In that case we do
eliminate an extra memory copy for all data in such circumstances, while
keeping the number of chunks very low. As such I'll most probably be adding
support for that locally in any case. If you think that is (in principle)
something that is worthwhile might also be merged into lwIP itself, I'd be
happy to make a proper patch out of it and submit it..
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