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From: David Miller <davem@davemloft.net>
To: roel.kluin@gmail.com
Cc: netdev@vger.kernel.org
Subject: Re: [TCP]: min_t/max_t confusion in tcp_select_initial_window()?
Date: Tue, 22 Dec 2009 19:47:47 -0800 (PST)	[thread overview]
Message-ID: <20091222.194747.193724694.davem@davemloft.net> (raw)
In-Reply-To: <4B3179B8.5000403@gmail.com>

From: Roel Kluin <roel.kluin@gmail.com>
Date: Wed, 23 Dec 2009 03:00:24 +0100

> I could be confused, but in net/ipv4/tcp_output.c:217:
> 
>                 space = max_t(u32, sysctl_tcp_rmem[2], sysctl_rmem_max);
>                 space = min_t(u32, space, *window_clamp);
> ------------------------^^^^^
> 
> shouldn't the min_t and max_t be exchanged? i.e.
> 
>                 space = min_t(u32, sysctl_tcp_rmem[2], sysctl_rmem_max);
>                 space = max_t(u32, space, *window_clamp);

It looks correct to me.

Globally, the largest window we could ever end up advertising
is the maximum of the sysctl_tcp_rmem[2] threshold and
sysctl_rmem_max.

But for this connection, the window clamp is our upper bound.

  reply	other threads:[~2009-12-23  3:47 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2009-12-23  2:00 [TCP]: min_t/max_t confusion in tcp_select_initial_window()? Roel Kluin
2009-12-23  3:47 ` David Miller [this message]
2009-12-23 19:45   ` Ilpo Järvinen
2009-12-23 21:15     ` David Miller
2009-12-23 21:23       ` Ilpo Järvinen
2010-08-18 14:09         ` Hagen Paul Pfeifer

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