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Re: [Lse-tech] Re: A common layer for Accounting packages

To: hadi@xxxxxxxxxx
Subject: Re: [Lse-tech] Re: A common layer for Accounting packages
From: Evgeniy Polyakov <johnpol@xxxxxxxxxxx>
Date: Mon, 28 Feb 2005 19:17:59 +0300
Cc: Thomas Graf <tgraf@xxxxxxx>, Andrew Morton <akpm@xxxxxxxx>, Guillaume Thouvenin <guillaume.thouvenin@xxxxxxxx>, kaigai@xxxxxxxxxxxxx, marcelo.tosatti@xxxxxxxxxxxx, "David S. Miller" <davem@xxxxxxxxxx>, jlan@xxxxxxx, lse-tech@xxxxxxxxxxxxxxxxxxxxx, linux-kernel@xxxxxxxxxxxxxxx, netdev@xxxxxxxxxxx, elsa-devel@xxxxxxxxxxxxxxxxxxxxx
In-reply-to: <1109604693.1072.8.camel@jzny.localdomain>
Organization: MIPT
References: <4221E548.4000008@ak.jp.nec.com> <20050227140355.GA23055@logos.cnet> <42227AEA.6050002@ak.jp.nec.com> <1109575236.8549.14.camel@frecb000711.frec.bull.fr> <20050227233943.6cb89226.akpm@osdl.org> <1109592658.2188.924.camel@jzny.localdomain> <20050228132051.GO31837@postel.suug.ch> <1109598010.2188.994.camel@jzny.localdomain> <20050228135307.GP31837@postel.suug.ch> <1109599803.2188.1014.camel@jzny.localdomain> <20050228142551.GQ31837@postel.suug.ch> <1109604693.1072.8.camel@jzny.localdomain>
Reply-to: johnpol@xxxxxxxxxxx
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On 28 Feb 2005 10:31:33 -0500
jamal <hadi@xxxxxxxxxx> wrote:

> On Mon, 2005-02-28 at 09:25, Thomas Graf wrote:
> > * jamal <1109599803.2188.1014.camel@xxxxxxxxxxxxxxxx> 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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