netdev - Re: [PATCH net-next] tcp: shrink tcp6_timewait

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Date:	Thu, 03 Oct 2013 12:47:22 -0700
From:	Eric Dumazet <eric.dumazet@...il.com>
To:	David Miller <davem@...emloft.net>
Cc:	netdev@...r.kernel.org
Subject: Re: [PATCH net-next] tcp: shrink tcp6_timewait_sock by one cache
 line

On Thu, 2013-10-03 at 15:31 -0400, David Miller wrote:

> Eric just use tcp_time_stamp in all of these locations, then you can
> lose the casts and still achieve your stated objective.

I thought about this, but this would break if tcp_time_stamp was no
longer tied to jiffies.

Van Jacobson had the idea of using finer resolution tcp_time_stamp for
TCP flows in data centers, for better RTT estimation and and cwin
control, but also for better diagnostics.

Note we used this (u32)jiffies thing in net/ipv4/inetpeer.c in the past,
and tp->tso_deferred is also a u32 value.

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