Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755816AbZIULmk (ORCPT ); Mon, 21 Sep 2009 07:42:40 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1755774AbZIULmi (ORCPT ); Mon, 21 Sep 2009 07:42:38 -0400 Received: from mail.gmx.net ([213.165.64.20]:59081 "HELO mail.gmx.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1755520AbZIULmf (ORCPT ); Mon, 21 Sep 2009 07:42:35 -0400 X-Authenticated: #25574588 X-Provags-ID: V01U2FsdGVkX1+PTNECMMyPzL7/tWSOrzMBddY+bWcvMk24VpYRnm OJB4TOjabSypyj Date: Tue, 22 Sep 2009 00:00:48 +1200 From: Johannes Buchner To: Arjan van de Ven Cc: linux-kernel@vger.kernel.org Subject: Re: Influence of optimization level, preemption and scheduler on boot time Message-Id: <20090922000048.0f9aa2b6.buchner.johannes@gmx.at> In-Reply-To: <20090921132059.10b2723d@infradead.org> References: <20090921232553.c97560c7.buchner.johannes@gmx.at> <20090921132059.10b2723d@infradead.org> X-Mailer: Sylpheed 2.6.0 (GTK+ 2.16.6; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: multipart/signed; protocol="application/pgp-signature"; micalg="PGP-SHA1"; boundary="Signature=_Tue__22_Sep_2009_00_00_48_+1200_hNs/AIxmEq1SBRWQ" X-Y-GMX-Trusted: 0 X-FuHaFi: 0.59 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2144 Lines: 61 --Signature=_Tue__22_Sep_2009_00_00_48_+1200_hNs/AIxmEq1SBRWQ Content-Type: text/plain; charset=ISO-8859-1 Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Mon, 21 Sep 2009 13:20:59 +0200 Arjan van de Ven wrote: > On Mon, 21 Sep 2009 23:25:53 +1200 > Johannes Buchner wrote: >=20 > > Hi all. > >=20 > > I measured the kernel (and system) boot times while varying the > > parameters: > > - Optimization level: -Os, -O2 and also -O3 > > - Preemptive model > > - Scheduler: CFQ, Anticipatory, Deadline, Noop > >=20 > > My conclusion was that the optimization level and the preemptive > > model had no significant influence on speed. CFQ let my system boot > > several seconds faster than the other schedulers. > >=20 > > Graphs can be found at: > > http://johannes.jakeapp.com/blog/?p=3D913 > >=20 > > This conclusion may not be true for all situations, but I found it > > interesting that the optimization level is so irrelevant. > >=20 >=20 > it's interesting to see that the IO scheduler mattered..=20 > I would think that (s)readahead makes the IO scheduler irrelevant for > boot time... I did not use (s)readahead though in this measurements. Trying readahead-list with CFQ did not bring me any improvement. Maybe, for the other schedulers, it brings the speed on par with CFQ. --=20 Emails k=F6nnen ge=E4ndert, gef=E4lscht und eingesehen werden. Signiere oder versch=FCssele deine Mails mit GPG. http://web.student.tuwien.ac.at/~e0625457/pgp.html --Signature=_Tue__22_Sep_2009_00_00_48_+1200_hNs/AIxmEq1SBRWQ Content-Type: application/pgp-signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.11 (GNU/Linux) iEYEARECAAYFAkq3avMACgkQ7X1+MfqVcr2VJACeL5NZ0y7xzW51spnpJgCfbyeR Sx4AnidNIpldcCV3BsyxbFDWxYjj+cpY =wWlc -----END PGP SIGNATURE----- --Signature=_Tue__22_Sep_2009_00_00_48_+1200_hNs/AIxmEq1SBRWQ-- -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/