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From: Eric Dumazet <eric.dumazet@gmail.com>
To: Rick Jones <rick.jones2@hp.com>
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Cc: Hal Murray <hmurray@megapathdsl.net>, bloat <bloat@lists.bufferbloat.net>
Subject: Re: [Bloat] SO_SNDBUF and SO_RCVBUF
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On Fri, 2015-04-24 at 09:31 -0700, Rick Jones wrote:
> > netperf -t TCP_STREAM" uses a default size of 16384 bytes per sendmsg.
> 
> Under Linux at least, and only because that is the default initial value 
> for SO_SNDBUF for a TCP socket (via tcp_wmem).
> 
> More generally, the default send size used by netperf is the value of 
> SO_SNDBUF for the data socket immediately after its creation.
> 

Yeah, this looks odd.

Note that right after a connect() or accept(), getsocktop(SO_SNDBUF)
might be very different than the 'default=16384'

Otherwise, we could not even send the first 10 packets for IW10 from one
sendmsg(), or a single full packet on loopback interface (MTU=65536)

Anyway, 16384 bytes as default buffer size on netperf is fine.