netdev - Re: Throughput regression with `tcp: refine TSO autosizing`

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Message-ID: <54D4FE63.9020602@hp.com>
Date:	Fri, 06 Feb 2015 09:48:19 -0800
From:	Rick Jones <rick.jones2@...com>
To:	Eric Dumazet <eric.dumazet@...il.com>,
	Michal Kazior <michal.kazior@...to.com>
CC:	Neal Cardwell <ncardwell@...gle.com>,
	linux-wireless <linux-wireless@...r.kernel.org>,
	Network Development <netdev@...r.kernel.org>,
	Eyal Perry <eyalpe@....mellanox.co.il>
Subject: Re: Throughput regression with `tcp: refine TSO autosizing`

> If you increase ability to flood on one flow, then you need to make sure
> receiver has big rcvbuf as well.
>
> echo 2000000 >/proc/sys/net/core/rmem_default
>
> Otherwise it might drop bursts.
>
> This is the kind of things that TCP does automatically, not UDP.

An alternative, if the application involved can make explicit 
setsockopt() calls to set SO_SNDBUF and/or SO_RCVBUF, is to tweak 
rmem_max and wmem_max and then let the application make the setsockopt() 
calls.

Which path one would take would depend on circumstances I suspect.

rick jones
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