Date: Mon, 28 Feb 2005 19:17:59 +0300
From: Evgeniy Polyakov <johnpol@2ka.mipt.ru>
To: hadi@cyberus.ca
Cc: Thomas Graf <tgraf@suug.ch>, Andrew Morton <akpm@osdl.org>,
       Guillaume Thouvenin <guillaume.thouvenin@bull.net>,
       kaigai@ak.jp.nec.com, marcelo.tosatti@cyclades.com,
       "David S. Miller" <davem@redhat.com>, jlan@sgi.com,
       lse-tech@lists.sourceforge.net, linux-kernel@vger.kernel.org,
       netdev@oss.sgi.com, elsa-devel@lists.sourceforge.net
Subject: Re: [Lse-tech] Re: A common layer for Accounting packages
Message-ID: <20050228191759.6f7b656e@zanzibar.2ka.mipt.ru>
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On 28 Feb 2005 10:31:33 -0500
jamal <hadi@cyberus.ca> wrote:

> On Mon, 2005-02-28 at 09:25, Thomas Graf wrote:
> > * jamal <1109599803.2188.1014.camel@jzny.localdomain> 2005-02-28 09:10
> [..]
> > > To justify writting the new code, I am assuming someone has actually sat
> > > down and in the minimal stuck their finger in the air
> > > and said "yes, there is definetely wind there".
> > 
> > I did, not for this problem though. The code this idea comes from sends
> > batched events 
> 
> I would bet the benefit you are seeing has to do with batching rather
> than such an optimization flag. Different ballgame.
> I relooked at their code snippet, they dont even have skbs built nor
> even figured out what sock or PID. That work still needs to be done it
> seems in cn_netlink_send(). So probably all they need to do is move the
> check in cn_netlink_send() instead. This is assuming they are not
> scratching their heads with some realted complexities.
> 
> I am gonna disapear for a while; hopefully the original posters have
> gathered some ideas from what we discussed.

As connector author, I still doubt it worth copying several lines 
from netlink_broadcast() before skb allocation in cn_netlink_send().
Of course it is easy and can be done, but I do not see any profit here.
Atomic allocation is fast, if it succeds,  but there are no groups/socket to send,
skb will be freed, if allocation fails, then group check is useless.

I would prefer Guillaume Thouvenin as fork connector author to test
his current implementation and show that connector's cost is negligible
both with and without userspace listeners.
As far as I remember it is first entry in fork connector's TODO list.

> cheers,
> jamal
> 


	Evgeniy Polyakov

Only failure makes us experts. -- Theo de Raadt
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