netdev - Re: [PATCH] ifb: add multi-queue support

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Message-ID: <4AF946BF.30800@gmail.com>
Date:	Tue, 10 Nov 2009 11:55:59 +0100
From:	Eric Dumazet <eric.dumazet@...il.com>
To:	Changli Gao <xiaosuo@...il.com>
CC:	Patrick McHardy <kaber@...sh.net>,
	"David S. Miller" <davem@...emloft.net>, netdev@...r.kernel.org,
	Tom Herbert <therbert@...gle.com>
Subject: Re: [PATCH] ifb: add multi-queue support

Changli Gao a écrit :
> On Tue, Nov 10, 2009 at 6:29 PM, Patrick McHardy <kaber@...sh.net> wrote:
>> I'm not sure how this will help, ifb device transmission is
>> still serialized by the ingress queue lock and the mirred lock.
>>
> 
> But not in ifb_thread. For firewall the main routine is after
> netif_rx_ni(). For server applications, the packets belong to the same
> flow are always routed to the same CPU, and the applications can
> benefit with better localization.
> 

Hmm, you know many cache lines already were bringed into cpu receiving
the original softirq ? But yes, this is a possible way to go / try :)

Please submit your future patch on top of net-next-2.6, because
I see you still use dev_get_by_index() :-(

commit 05e8689c9a3a208bf75b60662778d81e23eac460
Author: Eric Dumazet <eric.dumazet@...il.com>
Date:   Sun Nov 1 19:45:16 2009 +0000

    ifb: RCU locking avoids touching dev refcount
    
    Avoids touching dev refcount in hotpath
    
    Signed-off-by: Eric Dumazet <eric.dumazet@...il.com>
    Signed-off-by: David S. Miller <davem@...emloft.net>

commit db519144243de6b17ff0c56c26f06059743110a7
Author: Eric Dumazet <eric.dumazet@...il.com>
Date:   Tue Oct 20 02:35:50 2009 +0000

    ifb: should not use __dev_get_by_index() without locks
    
    At this point (ri_tasklet()), RTNL or dev_base_lock are not held,
    we must use dev_get_by_index() instead of __dev_get_by_index()
    
    Signed-off-by: Eric Dumazet <eric.dumazet@...il.com>
    Signed-off-by: David S. Miller <davem@...emloft.net>


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