Re: Strange TCP behavior

Andi Kleen (ak@muc.de)
09 Aug 1998 01:09:14 +0200


Bernd Paysan <bernd.paysan@gmx.de> writes:

[...]
> so it seems to be connected with an 128K limit (I tried other values, and
> indeed, once you fill 128k with small chunks, the kernel seems urged to
> wait).
>
> Is this a bug/feature? Has anybody an idea why there is an 128k limit, and
> why it doesn't matter once the chunk size is 1024 bytes or larger? I don't
> think it affects real world benchmarks, but who knows.

Seems to be a buffer management problem. When one changes the default
buffer sizes to 128K (in /proc/sys/net/core/[rw]mem_{max,default}) then
the degradation is at the start, not in the middle. I does not seem to
be prune_queue() related too - prune_queue is never called.

-Andi

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