From: David Miller <davem@davemloft.net>
To: eric.dumazet@gmail.com
Cc: bhutchings@solarflare.com, netdev@vger.kernel.org
Subject: Re: [PATCH] net: force dst_default_metrics to const section
Date: Wed, 08 Aug 2012 16:00:51 -0700 (PDT) [thread overview]
Message-ID: <20120808.160051.2296746021327619852.davem@davemloft.net> (raw)
In-Reply-To: <1344372945.28967.165.camel@edumazet-glaptop>
From: Eric Dumazet <eric.dumazet@gmail.com>
Date: Tue, 07 Aug 2012 22:55:45 +0200
> [PATCH v2] net: force dst_default_metrics to const section
>
> While investigating on network performance problems, I found this little
> gem :
>
> $ nm -v vmlinux | grep -1 dst_default_metrics
> ffffffff82736540 b busy.46605
> ffffffff82736560 B dst_default_metrics
> ffffffff82736598 b dst_busy_list
>
> Apparently, declaring a const array without initializer put it in
> (writeable) bss section, in middle of possibly often dirtied cache
> lines.
>
> Since we really want dst_default_metrics be const to avoid any possible
> false sharing and catch any buggy writes, I force a null initializer.
>
> ffffffff818a4c20 R dst_default_metrics
>
> Signed-off-by: Eric Dumazet <edumazet@google.com>
> Cc: Ben Hutchings <bhutchings@solarflare.com>
Applied, thanks.
next prev parent reply other threads:[~2012-08-08 23:00 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-08-07 16:11 [PATCH] net: force dst_default_metrics to const section Eric Dumazet
2012-08-07 20:15 ` Ben Hutchings
2012-08-07 20:55 ` Eric Dumazet
2012-08-07 22:12 ` Ben Hutchings
2012-08-07 22:34 ` Eric Dumazet
2012-08-07 22:44 ` Ben Hutchings
2012-08-07 22:56 ` Eric Dumazet
2012-08-07 23:17 ` David Miller
2012-08-08 23:00 ` David Miller [this message]
2012-08-07 21:55 ` David Miller
2012-08-07 22:09 ` Eric Dumazet
2012-08-07 22:11 ` Eric Dumazet
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