netdev - Re: [PATCH v2 net-next] tcp: shrink tcp6_timewait

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Message-Id: <20131003.174357.89621984330679119.davem@davemloft.net>
Date:	Thu, 03 Oct 2013 17:43:57 -0400 (EDT)
From:	David Miller <davem@...emloft.net>
To:	eric.dumazet@...il.com
Cc:	netdev@...r.kernel.org
Subject: Re: [PATCH v2 net-next] tcp: shrink tcp6_timewait_sock by one
 cache line

From: Eric Dumazet <eric.dumazet@...il.com>
Date: Thu, 03 Oct 2013 14:27:25 -0700

> From: Eric Dumazet <edumazet@...gle.com>
> 
> While working on tcp listener refactoring, I found that it
> would really make things easier if sock_common could include
> the IPv6 addresses needed in the lookups, instead of doing
> very complex games to get their values (depending on sock
> being SYN_RECV, ESTABLISHED, TIME_WAIT)
> 
> For this to happen, I need to be sure that tcp6_timewait_sock
> and tcp_timewait_sock consume same number of cache lines.
> 
> This is possible if we only use 32bits for tw_ttd, as we remove
> one 32bit hole in inet_timewait_sock
> 
> inet_tw_time_stamp() is defined and used, even if its current
> implementation looks like tcp_time_stamp : We might need finer
> resolution for tcp_time_stamp in the future.
> 
> Before patch : sizeof(struct tcp6_timewait_sock) = 0xc8
> 
> After patch : sizeof(struct tcp6_timewait_sock) = 0xc0
> 
> Signed-off-by: Eric Dumazet <edumazet@...gle.com>
> ---
> v2: add a inet_tw_time_stamp() helper, per David request.

Looks great, applied, thanks Eric.
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