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

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Date:	Tue, 07 Jun 2011 05:19:25 +0200
From:	Eric Dumazet <eric.dumazet@...il.com>
To:	Lucian Adrian Grijincu <lucian.grijincu@...il.com>
Cc:	netdev@...r.kernel.org, "David S. Miller" <davem@...emloft.net>
Subject: Re: [PATCH 2/2] net: dummy: allocate devices with alloc_netdev_id

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
# uptime
 05:18:45 up 13:35,  3 users,  load average: 12159.82, 10277.39, 5623.19



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