[Cerowrt-devel] looking over ampdu stats

Sujith Manoharan sujith at msujith.org
Mon Jan 20 10:35:02 EST 2014

David P. Reed wrote:
> It's worth remembering that while aggregation of data in single units might
> reduce overhead, end to end latency is far more critical to most Internet
> apps.
> Focusing on optimizing throughput for the last few percent in corner cases is
> NOT desirable.  In fact, it is the cause of pervasive buffer bloated designs,
> and the creator of "Daddy broke the Internet" scenarios.
> Since LTE is badly configured in the field for Internet use, causing denial of
> service to many users because of bloated (multisecond to drain) queues, I
> would stop focusing on this, which is only a 10 percent issue.  Multisecond
> bloat is a disaster. You are fiddling while Rome burns imo.

Well, the 10 percent is with a 1x1 card. It becomes worse with 2x2 and with 3x3,
it's really bad - about 180 Mbps when it should be close to 290 Mbps. Using more
parallel threads appears to improve things, but I don't see this behavior with
a windows client, where a single iperf stream gives good results, unlike ath9k.


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