netdev - Re: [PATCH net-next] tcp: increase size at which tcp_bound_to_half_wnd bounds to > TCP_MSS

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Message-ID: <1467115090.6850.202.camel@edumazet-glaptop3.roam.corp.google.com>
Date:	Tue, 28 Jun 2016 13:58:10 +0200
From:	Eric Dumazet <eric.dumazet@...il.com>
To:	"Seymour, Shane M" <shane.seymour@....com>
Cc:	"netdev@...r.kernel.org" <netdev@...r.kernel.org>
Subject: Re: [PATCH net-next] tcp: increase size at which
 tcp_bound_to_half_wnd bounds to > TCP_MSS_DEFAULT

On Tue, 2016-06-28 at 04:33 +0000, Seymour, Shane M wrote:
> In previous commit 01f83d69844d307be2aa6fea88b0e8fe5cbdb2f4
> the following comments were added:
> 
> "When peer uses tiny windows, there is no use in packetizing to sub-MSS
> pieces for the sake of SWS or making sure there are enough packets in
> the pipe for fast recovery."
> 
> The test should be > TCP_MSS_DEFAULT not >= 512. This allows low end
> devices that send an MSS of 536 (TCP_MSS_DEFAULT) to see better network
> performance by sending it 536 bytes of data at a time instead of bounding
> to half window size (268). Other network stacks work this way, e.g. HP-UX.


Trying to cope with ridiculous windows these days is really a waste of
time, as we perform this check for all tcp sendmsg() calls :(

Anyway, your patch is reversed.