netdev - Re: PATCH net-next-2.6] linkwatch: linkwatch_forget

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Message-ID: <20091116143917.14e4fa4f@s6510>
Date:	Mon, 16 Nov 2009 14:39:17 -0800
From:	Stephen Hemminger <shemminger@...tta.com>
To:	Eric Dumazet <eric.dumazet@...il.com>
Cc:	"David S. Miller" <davem@...emloft.net>,
	Herbert Xu <herbert@...dor.apana.org.au>,
	Linux Netdev List <netdev@...r.kernel.org>
Subject: Re: PATCH net-next-2.6] linkwatch: linkwatch_forget_dev() to
 speedup device dismantle

On Mon, 16 Nov 2009 22:50:48 +0100
Eric Dumazet <eric.dumazet@...il.com> wrote:

> vlan_dev_stop() ->
> 	netif_carrier_off(dev) ->
> 		linkwatch_fire_event(dev) ->
> 			dev_hold() ...
> 
> And __linkwatch_run_queue() runs up to one second later...
> 
> A generic fix to this problem is to add a linkwatch_forget_dev() method
> to unlink the device from the list of watched devices.
> 
> dev->link_watch_next becomes dev->link_watch_list (and use a bit more memory),
> to be able to unlink device in O(1).
> 
> After patch :
> time ip link del eth3.103 ; time ip link del eth3.104 ; time ip link del eth3.105
> 
> real    0m0.024s
> user    0m0.000s
> sys     0m0.000s
> 
> real    0m0.032s
> user    0m0.000s
> sys     0m0.001s
> 
> real    0m0.033s
> user    0m0.000s
> sys     0m0.000s
> 
> 
> Signed-off-by: Eric Dumazet <eric.dumazet@...il.com>

Acked-by: Stephen Hemminger <shemminger@...tta.com>
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