From: Stephen Hemminger <shemminger@vyatta.com>
To: Dmitry Popov <dp@highloadlab.com>
Cc: "David S. Miller" <davem@davemloft.net>,
William.Allen.Simpson@gmail.com,
"Eric Dumazet" <eric.dumazet@gmail.com>,
"Andreas Petlund" <apetlund@simula.no>,
"Ilpo Järvinen" <ilpo.jarvinen@helsinki.fi>,
"Alexey Kuznetsov" <kuznet@ms2.inr.ac.ru>,
"Pekka Savola (ipv6)" <pekkas@netcore.fi>,
"James Morris" <jmorris@namei.org>,
"Hideaki YOSHIFUJI" <yoshfuji@linux-ipv6.org>,
"Patrick McHardy" <kaber@trash.net>,
"Herbert Xu" <herbert@gondor.hengli.com.au>,
"Gilad Ben-Yossef" <gilad@codefidence.com>,
"Yony Amit" <yony@comsleep.com>, "Zhu Yi" <yi.zhu@intel.com>,
linux-kernel@vger.kernel.org, netdev@vger.kernel.org
Subject: Re: [PATCH] tcp: md5 signature check scaling
Date: Wed, 27 Oct 2010 08:56:03 -0700 [thread overview]
Message-ID: <20101027085603.490e326b@nehalam> (raw)
In-Reply-To: <AANLkTi=U1smX6XXDMyBTicyqbUU5V-t56jmH7qtX2XW5@mail.gmail.com>
On Wed, 27 Oct 2010 16:52:30 +0400
Dmitry Popov <dp@highloadlab.com> wrote:
> From: Dmitry Popov <dp@highloadlab.com>
>
> TCP MD5 signature checking without socket lock.
>
> Each tcp_sock has 2 RCU-protected arrays (tcp[46]_md5sig_info) of
> tcp[46]_md5sig_key address-key pairs.
> Each key (tcp_md5sig_key) has kref struct so that there is no need to
> lock the whole array to work with one key.
>
> MD5 functions were rewritten according to above statement and hash
> check (tcp_v4_inbound_md5_hash) was moved before socket lock.
>
> Signed-off-by: Dmitry Popov <dp@highloadlab.com>
You traded locking for ref counting which may not be as big
a win as your think.
Also, the overhead of RCU here might impact tests that involve
lots of socket creation and destruction.
--
prev parent reply other threads:[~2010-10-27 15:56 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-10-27 12:52 [PATCH] tcp: md5 signature check scaling Dmitry Popov
2010-10-27 13:00 ` Eric Dumazet
2010-10-27 13:18 ` Dmitry Popov
2010-10-27 15:56 ` Stephen Hemminger [this message]
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