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From: Eric Dumazet <eric.dumazet@gmail.com>
To: "Timo Teräs" <timo.teras@iki.fi>
Cc: David Miller <davem@davemloft.net>, netdev@vger.kernel.org
Subject: Re: [PATCH] ipv4: synchronize bind() with RTM_NEWADDR notifications
Date: Thu, 21 Oct 2010 13:12:57 +0200	[thread overview]
Message-ID: <1287659577.6871.69.camel@edumazet-laptop> (raw)
In-Reply-To: <4CC01CC0.7090101@iki.fi>

Le jeudi 21 octobre 2010 à 13:58 +0300, Timo Teräs a écrit :
> On 10/21/2010 01:50 PM, David Miller wrote:
> > From: Timo Teräs <timo.teras@iki.fi>
> > Date: Thu, 21 Oct 2010 13:41:37 +0300
> > 
> >> Is inet_bind() called from non-userland context? If yes, then this is a
> >> bad idea. Otherwise I don't think it's that hot path...
> > 
> > It is.
> 
> Yet, almost immediately after that there is lock_sock() which can also
> sleep. How does that work then?
> 

I am not sure I understand your question. Maybe my answer wont be clear.

rtnl_lock() can take ages on some setups, because its using one single
and shared mutex. Its use should be restricted to administrative
purposes.

bind() is a pretty hot path on many workloads, this is hardly what we
call an administrative task.

lock_sock() uses a per socket lock, and it is a _bit_ more scalable, you
can have 4096 cpus all using bind()/recv()/send()/... at the same time,
it just works.




      parent reply	other threads:[~2010-10-21 11:13 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2010-10-21 10:12 [PATCH] ipv4: synchronize bind() with RTM_NEWADDR notifications Timo Teräs
2010-10-21 10:25 ` Eric Dumazet
2010-10-21 10:41   ` Timo Teräs
2010-10-21 10:50     ` David Miller
2010-10-21 10:58       ` Timo Teräs
2010-10-21 11:03         ` David Miller
2010-10-21 11:29           ` Timo Teräs
2010-10-21 11:34             ` David Miller
2010-10-21 11:57               ` Timo Teräs
2010-10-21 13:06                 ` [PATCH v2] " Timo Teräs
2010-10-21 14:10                   ` Eric Dumazet
2010-10-21 19:01                     ` Timo Teräs
2010-10-21 11:12         ` Eric Dumazet [this message]

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