Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751227AbaLBIga (ORCPT ); Tue, 2 Dec 2014 03:36:30 -0500 Received: from cantor2.suse.de ([195.135.220.15]:57273 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750991AbaLBIg3 (ORCPT ); Tue, 2 Dec 2014 03:36:29 -0500 Date: Tue, 2 Dec 2014 19:36:18 +1100 From: NeilBrown To: zhangxiao Cc: , , dm-devel@redhat.com Subject: Re: The DM_BUFIO_HASH_BITS is defined as 20, any plan to make it flexible? Message-ID: <20141202193618.6d3adb22@notabene.brown> In-Reply-To: <547D790E.3070803@windriver.com> References: <547D790E.3070803@windriver.com> X-Mailer: Claws Mail 3.10.1-162-g4d0ed6 (GTK+ 2.24.25; x86_64-suse-linux-gnu) MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; boundary="Sig_/iqrv+YBv2YSq+gkIP4eRvf."; protocol="application/pgp-signature" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org --Sig_/iqrv+YBv2YSq+gkIP4eRvf. Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: quoted-printable On Tue, 2 Dec 2014 16:32:14 +0800 zhangxiao wrot= e: > Hi NeilBrown, >=20 > See drivers/md/dm-bufio.c as below: > 50 /* > 51 * Buffer hash > 52 */ > 53 #define DM_BUFIO_HASH_BITS 20 > 54 #define DM_BUFIO_HASH(block) \ > 55 ((((block) >> DM_BUFIO_HASH_BITS) ^ (block)) & \ > 56 ((1 << DM_BUFIO_HASH_BITS) - 1)) > "drivers/md/dm-bufio.c" 1854L, 45375C=20 >=20 >=20 > DM_BUFIO_HASH_BITS was defined as 20 and it maybe not fit for some > use case with limited resources. Do we have any plan to make it more > flexible? Like module parameter or something else? >=20 Thanks, but this question should be address to: DEVICE-MAPPER (LVM) M: Alasdair Kergon M: Mike Snitzer M: dm-devel@redhat.com L: dm-devel@redhat.com W: http://sources.redhat.com/dm Q: http://patchwork.kernel.org/project/dm-devel/list/ T: git git://git.kernel.org/pub/scm/linux/kernel/git/device-mapper/linux-dm= .git T: quilt http://people.redhat.com/agk/patches/linux/editing/ S: Maintained F: Documentation/device-mapper/ F: drivers/md/dm* F: drivers/md/persistent-data/ F: include/linux/device-mapper.h F: include/linux/dm-*.h F: include/uapi/linux/dm-*.h NeilBrown --Sig_/iqrv+YBv2YSq+gkIP4eRvf. Content-Type: application/pgp-signature Content-Description: OpenPGP digital signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v2 iQIVAwUBVH16Ajnsnt1WYoG5AQLYrQ/9GmB7gctdLEMnnmeWEW3xrG0zdylEqsXl bETJLu3sS2NHwY5t0hiYBpTZBy6G1OlpNpVN5Xx47OTYYx76ALCXAgxwDjImEhKo Gm6fJo0M35iMha4CwOttqzvdGVyNPDIC8V1sqICjuwT1UHgbH8vhuV5G8hGy2gRw 2ldHR5pyITyExkLyE/h6OVfjzzSvEx8VVE+q5pWrpVU3pVfj7FYVlvELSxbBEvlW F5bRfYpoIgz7cgz/uL33EJDBlK4j6HnYzPPCJ18N01XYM/Y6c0S15ly+4P0mx3a/ OJQfCECn7uVP6KlFBV7VQnVS2/KbZdbuneDHUKLRBi9ol+8/7oErThAFsanDUZRP 3Y5Ywdsvv3/h109XeV3B3+UuTppzX91vS6ZKA7tIvSSWzuLVGiGEICgCkBdYeRIN 6lwqSn1tWUq/QYIUi72+0lgxqw/uJ/xUVkGfNaVexEho1wfvQ1YauHopyIR6C2St k5CPhJWQTA3F4QxN5gbyLaplV4LdPszsHdq4BOn3ovJzloekquHMaQWaJako/+3X 5za5/7bFfSEDF0wQAvA3iS5UgQBAG6PE9o7J4XIZlgDe84GZ6XzzYrwD9G1cMOPm g1piV8baixvsGUb1EJcYKzkiEhBH6aiyJWQSaYAsCGf+eqSPSujn1FzNjsWTM4wi slvLd7ZEAnw= =Mt2m -----END PGP SIGNATURE----- --Sig_/iqrv+YBv2YSq+gkIP4eRvf.-- -- 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/