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From: David Miller <davem@davemloft.net>
To: bigeasy@linutronix.de
Cc: netdev@vger.kernel.org, rostedt@goodmis.org, tglx@linutronix.de
Subject: Re: [PATCH] net: make neigh_priv_len in struct net_device 16bit instead of 8bit
Date: Thu, 12 Dec 2013 15:35:26 -0500 (EST)	[thread overview]
Message-ID: <20131212.153526.1142755230387840010.davem@davemloft.net> (raw)
In-Reply-To: <1386839759-24042-1-git-send-email-bigeasy@linutronix.de>

From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Date: Thu, 12 Dec 2013 10:15:59 +0100

> neigh_priv_len is defined as u8. With all debug enabled struct
> ipoib_neigh has 200 bytes. The largest part is sk_buff_head with 96
> bytes and here the spinlock with 72 bytes.
> The size value still fits in this u8 leaving some room for more.
> 
> On -RT struct ipoib_neigh put on weight and has 392 bytes. The main
> reason is sk_buff_head with 288 and the fatty here is spinlock with 192
> bytes. This does no longer fit into into neigh_priv_len and gcc
> complains.
> 
> This patch changes neigh_priv_len from being 8bit to 16bit. Since the
> following element (dev_id) is 16bit followed by a spinlock which is
> aligned, the struct remains with a total size of 3200 (allmodconfig) /
> 2048 (with as much debug off as possible) bytes on x86-64.
> On x86-32 the struct is 1856 (allmodconfig) / 1216 (with as much debug
> off as possible) bytes long. The numbers were gained with and without
> the patch to prove that this change does not increase the size of the
> struct.
> 
> Cc: Steven Rostedt <rostedt@goodmis.org>
> Cc: Thomas Gleixner <tglx@linutronix.de>
> Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>

This is fine, applied, thanks.

      parent reply	other threads:[~2013-12-12 20:35 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2013-12-12  9:15 [PATCH] net: make neigh_priv_len in struct net_device 16bit instead of 8bit Sebastian Andrzej Siewior
2013-12-12 15:57 ` Steven Rostedt
2013-12-12 17:56   ` Arnaldo Carvalho de Melo
2013-12-12 20:35 ` David Miller [this message]

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