From mboxrd@z Thu Jan 1 00:00:00 1970 From: Eric Dumazet Subject: Re: [PATCH 2/2] net: dummy: allocate devices with alloc_netdev_id Date: Tue, 07 Jun 2011 05:19:25 +0200 Message-ID: <1307416765.2642.37.camel@edumazet-laptop> References: <1307410786-19110-1-git-send-email-lucian.grijincu@gmail.com> <1307410786-19110-3-git-send-email-lucian.grijincu@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: QUOTED-PRINTABLE Cc: netdev@vger.kernel.org, "David S. Miller" To: Lucian Adrian Grijincu Return-path: Received: from mail-wy0-f174.google.com ([74.125.82.174]:36112 "EHLO mail-wy0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753199Ab1FGDT3 (ORCPT ); Mon, 6 Jun 2011 23:19:29 -0400 Received: by wya21 with SMTP id 21so3245127wya.19 for ; Mon, 06 Jun 2011 20:19:28 -0700 (PDT) In-Reply-To: <1307410786-19110-3-git-send-email-lucian.grijincu@gmail.com> Sender: netdev-owner@vger.kernel.org List-ID: Le mardi 07 juin 2011 =C3=A0 04:39 +0300, Lucian Adrian Grijincu a =C3=A9= crit : > The most like case is that no one else is registering devices with a > name like "dummy%d". >=20 > 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). >=20 > $ time modprobe dummy numdummies=3D5000 > - with alloc_netdev : 9.50s > - with alloc_netdev_id: 3.50s >=20 > 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=3D5000 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, 5623.1= 9