netdev - Re: [PATCH] tcp: sysctl for initial receive window

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Message-ID: <1348248873.3103.57.camel@localhost>
Date:	Fri, 21 Sep 2012 19:34:33 +0200
From:	Jesper Dangaard Brouer <brouer@...hat.com>
To:	Eric Dumazet <eric.dumazet@...il.com>
Cc:	netdev@...r.kernel.org, Nandita Dukkipati <nanditad@...gle.com>
Subject: Re: [PATCH] tcp: sysctl for initial receive window

On Fri, 2012-09-21 at 17:25 +0200, Eric Dumazet wrote:
> On Fri, 2012-09-21 at 10:55 +0200, Jesper Dangaard Brouer wrote:
> > Make it possible to adjust the TCP default initial advertised receive
> > window, via sysctl /proc/sys/net/ipv4/tcp_init_recv_window.
> > 
> > The window size is this value multiplied by the MSS of the connection.
> > The default value is (still) 10, as descibed in commit 356f039822b
> > (TCP: increase default initial receive window.)
> > 
> > Allow minimum value of 1, but recommend against setting value below 2
> > in the documentation.
> > 
> > Its possible to control/override this value per route table entry via
> > the iproute2 option initrwnd.  Having the global default exported via
> > sysctl, helps determine the default setting, and make is easier to
> > adjust.
> 
> I was wondering why its not symmetric :
> 
> If we add a sysctl for initial receive window, we need another one for
> initial send window ?

Yes, that was also part of my plan (I just didn't have time to complete
it).  I'll implement the sysctl for initial congestion window, next
week.

Just wanted some initial feedback, on if this sysctl approach is
acceptable or not.

-- 
Best regards,
  Jesper Dangaard Brouer
  MSc.CS, Sr. Network Kernel Developer at Red Hat
  Author of http://www.iptv-analyzer.org
  LinkedIn: http://www.linkedin.com/in/brouer


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