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From: Eric Dumazet <eric.dumazet@gmail.com>
To: Rick Jones <rick.jones2@hp.com>
Cc: Hal Murray <hmurray@megapathdsl.net>,
	bloat <bloat@lists.bufferbloat.net>
Subject: Re: [Bloat] SO_SNDBUF and SO_RCVBUF
Date: Fri, 24 Apr 2015 11:41:17 -0700	[thread overview]
Message-ID: <1429900877.22254.133.camel@edumazet-glaptop2.roam.corp.google.com> (raw)
In-Reply-To: <553A6FF1.7090508@hp.com>

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.



  reply	other threads:[~2015-04-24 18:41 UTC|newest]

Thread overview: 19+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-04-22 19:10 Hal Murray
2015-04-22 19:26 ` Rick Jones
2015-04-22 19:28 ` Dave Taht
2015-04-22 21:02   ` Eric Dumazet
2015-04-22 21:05     ` Rick Jones
2015-04-22 21:46       ` Eric Dumazet
2015-04-22 22:20         ` Simon Barber
2015-04-22 23:08           ` Eric Dumazet
2015-04-24  4:37       ` Dave Taht
2015-04-24  4:40         ` Dave Taht
2015-04-24 13:50           ` Eric Dumazet
2015-04-24 14:34             ` Dave Taht
2015-04-24 16:31             ` Rick Jones
2015-04-24 18:41               ` Eric Dumazet [this message]
2015-04-24  5:23         ` Eric Dumazet
2015-04-22 21:07     ` Steinar H. Gunderson
2015-04-22 21:42       ` Eric Dumazet
2015-04-22 21:47         ` Dave Taht
2015-04-22 22:11         ` Steinar H. Gunderson

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