From mboxrd@z Thu Jan 1 00:00:00 1970 From: Eric Dumazet Subject: Re: Loopback performance from kernel 2.6.12 to 2.6.37 Date: Tue, 09 Nov 2010 07:42:13 +0100 Message-ID: <1289284933.2790.91.camel@edumazet-laptop> References: <1288954189.28003.178.camel@firesoul.comx.local> <1288988955.2665.297.camel@edumazet-laptop> <1289213926.15004.19.camel@firesoul.comx.local> <1289214289.2820.188.camel@edumazet-laptop> <1289228785.2820.203.camel@edumazet-laptop> <1289280152.2790.23.camel@edumazet-laptop> <1289283797.2790.84.camel@edumazet-laptop> <1289284715.2790.87.camel@edumazet-laptop> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: QUOTED-PRINTABLE Cc: Jesper Dangaard Brouer , netdev To: Andrew Hendry Return-path: Received: from mail-ww0-f44.google.com ([74.125.82.44]:62131 "EHLO mail-ww0-f44.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752786Ab0KIGmZ (ORCPT ); Tue, 9 Nov 2010 01:42:25 -0500 Received: by wwi18 with SMTP id 18so452994wwi.1 for ; Mon, 08 Nov 2010 22:42:24 -0800 (PST) In-Reply-To: <1289284715.2790.87.camel@edumazet-laptop> Sender: netdev-owner@vger.kernel.org List-ID: Le mardi 09 novembre 2010 =C3=A0 07:38 +0100, Eric Dumazet a =C3=A9crit= : > Hmm, your clock source is HPET, that might explain the problem on a > scheduler intensive workload. >=20 And if a packet sniffer (dhclient for example) makes all packets being timestamped, it also can explain a slowdown, even if there is no scheduler artifacts. cat /proc/net/packet > My HP dev machine > # grep . /sys/devices/system/clocksource/clocksource0/* > /sys/devices/system/clocksource/clocksource0/available_clocksource:ts= c hpet acpi_pm=20 > /sys/devices/system/clocksource/clocksource0/current_clocksource:tsc >=20 > My laptop: > $ grep . /sys/devices/system/clocksource/clocksource0/* > /sys/devices/system/clocksource/clocksource0/available_clocksource:ts= c hpet acpi_pm=20 > /sys/devices/system/clocksource/clocksource0/current_clocksource:tsc >=20