Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Tue, 26 Mar 2002 21:28:02 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Tue, 26 Mar 2002 21:27:53 -0500 Received: from etpmod.phys.tue.nl ([131.155.111.35]:8239 "EHLO etpmod.phys.tue.nl") by vger.kernel.org with ESMTP id ; Tue, 26 Mar 2002 21:27:39 -0500 Date: Wed, 27 Mar 2002 03:27:37 +0100 From: Kurt Garloff To: Trond Myklebust Cc: Linux kernel list Subject: linux-2.4.18-rpc_tweaks.dif Message-ID: <20020327032736.G15481@gum01m.etpnet.phys.tue.nl> Mail-Followup-To: Kurt Garloff , Trond Myklebust , Linux kernel list Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="N8NGGaQn1mzfvaPg" Content-Disposition: inline User-Agent: Mutt/1.3.22.1i X-Operating-System: Linux 2.4.16-schedJ2 i686 X-PGP-Info: on http://www.garloff.de/kurt/mykeys.pgp X-PGP-Key: 1024D/1C98774E, 1024R/CEFC9215 Organization: TU/e(NL), SuSE(DE) Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org --N8NGGaQn1mzfvaPg Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable Hi Trond, http://www.fys.uio.no/~trondmy/src/2.4.18/linux-2.4.18-rpc_tweaks.dif contains a change that causes devastating NFS client performance: My NFS read performance on a switched 100BaseT went down from >9MB/s to 500kB/s. (NFSv3, rsize=3D8192, 2.4.16 AXP kernel nfsd server) The reason is that xprt_adjust_cwnd() does no longer do what the comment above says it should do: _slowly_ increase cwnd until we start to hit the limit (which we see from timed out requests). Instead cwnd gets bumped very fast resulting in lots of timed out requests. This way you get fast oscillations in cwnd. Putting the old code back for xprt_adjust_cwnd() gave me back the old performance. Except for the missing damping, comparing the functionality with the old code, e.g. this snippet + if (xprt->cong > cwnd) + goto out; also makes me wonder whether it could be correct.=20 Please have a look at it again! Regards, --=20 Kurt Garloff [Eindhoven, NL] Physics: Plasma simulations [TU Eindhoven, NL] Linux: SCSI, Security [SuSE Nuernberg, DE] (See mail header or public key servers for PGP2 and GPG public keys.) --N8NGGaQn1mzfvaPg Content-Type: application/pgp-signature Content-Disposition: inline -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.0.6 (GNU/Linux) Comment: For info see http://www.gnupg.org iD8DBQE8oS4YxmLh6hyYd04RAoc8AKDO9xdbWIu4sHcH/VuLz7OCUDOgAACgqtqg 0vLVr/V058f/ObbzypqXsNU= =7J7i -----END PGP SIGNATURE----- --N8NGGaQn1mzfvaPg-- - 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/