netdev - Re: [PATCH 2/2] net: dummy: allocate devices with alloc_netdev

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Message-Id: <20110606.203851.1325136360346365091.davem@davemloft.net>
Date:	Mon, 06 Jun 2011 20:38:51 -0700 (PDT)
From:	David Miller <davem@...emloft.net>
To:	eric.dumazet@...il.com
Cc:	lucian.grijincu@...il.com, netdev@...r.kernel.org
Subject: Re: [PATCH 2/2] net: dummy: allocate devices with alloc_netdev_id

From: Eric Dumazet <eric.dumazet@...il.com>
Date: Tue, 07 Jun 2011 05:19:25 +0200

> Le mardi 07 juin 2011 à 04:39 +0300, Lucian Adrian Grijincu a écrit :
>> The most like case is that no one else is registering devices with a
>> name like "dummy%d".
>> 
>> We can bring the complexity down by replacing:
>> - alloc_netdev_id which is O(N) with
>> - alloc_netdev_id which, on the average case, is O(1).
>> 
>> $ time modprobe dummy numdummies=5000
>> - with alloc_netdev   : 9.50s
>> - with alloc_netdev_id: 3.50s
>> 
>> NOTE: Stats generated on a heavily patched 3.0-rc1 which replaces the
>>       current O(N^2) sysctl algorithm with a better one.
> 
> Yes, and disabled hotplug I guess.
> 
> Dont try this on a random computer ;)
> 
> # time modprobe dummy numdummies=5000
> 
> real	4m45.646s
> user	0m0.000s
> sys	0m12.440s
> # uptime
>  05:13:46 up 13:30,  3 users,  load average: 11221.41, 6918.70, 3101.12

ROFL
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