Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758949AbXKLN0d (ORCPT ); Mon, 12 Nov 2007 08:26:33 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1758378AbXKLN0Z (ORCPT ); Mon, 12 Nov 2007 08:26:25 -0500 Received: from viefep18-int.chello.at ([213.46.255.22]:9348 "EHLO viefep14-int.chello.at" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1758260AbXKLN0Y (ORCPT ); Mon, 12 Nov 2007 08:26:24 -0500 Subject: Re: iozone write 50% regression in kernel 2.6.24-rc1 From: Peter Zijlstra To: "Zhang, Yanmin" Cc: LKML In-Reply-To: <1194861112.20251.124.camel@ymzhang> References: <1194601672.20251.60.camel@ymzhang> <1194602064.6289.157.camel@twins> <1194833640.20251.80.camel@ymzhang> <1194860728.7179.6.camel@twins> <1194861112.20251.124.camel@ymzhang> Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="=-COOLTh5X0xXPQdAeAAAy" Date: Mon, 12 Nov 2007 14:26:20 +0100 Message-Id: <1194873980.7179.31.camel@twins> Mime-Version: 1.0 X-Mailer: Evolution 2.12.0 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2772 Lines: 97 --=-COOLTh5X0xXPQdAeAAAy Content-Type: text/plain Content-Transfer-Encoding: quoted-printable Single socket, dual core opteron, 2GB memory Single SATA disk, ext3 x86_64 kernel and userland (dirty_background_ratio, dirty_ratio) tunables ---- (5,10) - default 2.6.23.1-42.fc8 #1 SMP 524288 4 59580 60356 524288 4 59247 61101 524288 4 61030 62831 2.6.24-rc2 #28 SMP PREEMPT 524288 4 49277 56582 524288 4 50728 61056 524288 4 52027 59758 524288 4 51520 62426 ---- (20,40) - similar to your 8GB 2.6.23.1-42.fc8 #1 SMP 524288 4 225977 447461 524288 4 232595 496848 524288 4 220608 478076 524288 4 203080 445230 2.6.24-rc2 #28 SMP PREEMPT 524288 4 54043 83585 524288 4 69949 516253 524288 4 72343 491416 524288 4 71775 492653 ---- (60,80) - overkill 2.6.23.1-42.fc8 #1 SMP 524288 4 208450 491892 524288 4 216262 481135 524288 4 221892 543608 524288 4 202209 574725 524288 4 231730 452482 2.6.24-rc2 #28 SMP PREEMPT 524288 4 49091 86471 524288 4 65071 217566 524288 4 72238 492172 524288 4 71818 492433 524288 4 71327 493954 While I see that the write speed as reported under .24 ~70MB/s is much lower than the one reported under .23 ~200MB/s, I find it very hard to believe my poor single SATA disk could actually do the 200MB/s for longer than its cache 8/16 MB (not sure). vmstat shows that actual IO is done, even though the whole 512MB could fit in cache, hence my suspicion that the ~70MB/s is the most realistic of the two. I'll have to look into what iozone actually does though and why this patch makes the output different. FWIW - because its a single backing dev it does get to 100% of the dirty limit after a few runs, so not sure what makes the difference. --=-COOLTh5X0xXPQdAeAAAy Content-Type: application/pgp-signature; name=signature.asc Content-Description: This is a digitally signed message part -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.6 (GNU/Linux) iD8DBQBHOFR8XA2jU0ANEf4RAoSnAJ99Xf+uRmISFCItACuI2JKQ1D2rfwCfRqAO qLual9eQV++mQb15Kj58+rg= =TWAj -----END PGP SIGNATURE----- --=-COOLTh5X0xXPQdAeAAAy-- - 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/