From owner-svn-src-all@FreeBSD.ORG Sat Aug 2 07:52:17 2014 Return-Path: Delivered-To: svn-src-all@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) (using TLSv1 with cipher ADH-AES256-SHA (256/256 bits)) (No client certificate requested) by hub.freebsd.org (Postfix) with ESMTPS id 1A0DFEB7; Sat, 2 Aug 2014 07:52:17 +0000 (UTC) Received: from aslan.scsiguy.com (mail.scsiguy.com [70.89.174.89]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by mx1.freebsd.org (Postfix) with ESMTPS id D32C72EED; Sat, 2 Aug 2014 07:52:16 +0000 (UTC) Received: from [192.168.0.61] (jt-mbp.home.scsiguy.org [192.168.0.61]) (authenticated bits=0) by aslan.scsiguy.com (8.14.8/8.14.8) with ESMTP id s727q9Cn017947 (version=TLSv1/SSLv3 cipher=AES128-SHA bits=128 verify=NO); Sat, 2 Aug 2014 01:52:10 -0600 (MDT) (envelope-from gibbs@scsiguy.com) Content-Type: multipart/signed; boundary="Apple-Mail=_E8F869C3-89C8-4548-ADEE-570FA3BAEF62"; protocol="application/pgp-signature"; micalg=pgp-sha1 Mime-Version: 1.0 (Mac OS X Mail 7.3 \(1878.6\)) Subject: Re: svn commit: r269404 - head/sys/cddl/compat/opensolaris/sys From: "Justin T. Gibbs" In-Reply-To: <53DC96E9.9020805@delphij.net> Date: Sat, 2 Aug 2014 01:51:56 -0600 Message-Id: References: <201408012233.s71MXNIx051919@svn.freebsd.org> <57D656EF-5D6B-428B-9DCE-7FA360B1407F@scsiguy.com> <53DC96E9.9020805@delphij.net> To: d@delphij.net X-Mailer: Apple Mail (2.1878.6) X-Content-Filtered-By: Mailman/MimeDel 2.1.18 Cc: svn-src-head@freebsd.org, svn-src-all@freebsd.org, src-committers@freebsd.org, Xin LI , "mav >> Alexander Motin" X-BeenThere: svn-src-all@freebsd.org X-Mailman-Version: 2.1.18 Precedence: list List-Id: "SVN commit messages for the entire src tree \(except for " user" and " projects" \)" List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sat, 02 Aug 2014 07:52:17 -0000 --Apple-Mail=_E8F869C3-89C8-4548-ADEE-570FA3BAEF62 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset=windows-1252 On Aug 2, 2014, at 1:44 AM, Xin Li wrote: > Signed PGP part > On 8/1/14 8:59 PM, Justin T. Gibbs wrote: > > On Aug 1, 2014, at 4:33 PM, Xin LI wrote: > > > >> Author: delphij Date: Fri Aug 1 22:33:23 2014 New Revision: > >> 269404 URL: http://svnweb.freebsd.org/changeset/base/269404 > >> > >> Log: Split gethrtime() and gethrtime_waitfree() and make the > >> former use nanouptime() instead of getnanouptime(). > >> nanouptime(9) provides more precise result at expense of being > >> slower. > >> > >> In r269223, gethrtime() is used as creation time of dbuf, which > >> in turn acts as portion of lookup key to maintain AVL invariant > >> where there can not be duplicate items. Before this change, > >> gethrtime() have preferred better execution time by sacrificing > >> precision, which may lead to panic on busy systems with: > >> > >> panic: avl_find() succeeded inside avl_add() > > > > I don=92t believe that r269223 requires a temporal ordering of the > > dbufs in the AVL, just unique entries. So why use an expensive > > operation like getting high resolution time? Can=92t we just use a > > PCPU counter and tag the dbufs with "CPU# << 48 | PCPU_counter=94? >=20 > What do you think about D521? (Alexander suggested similar > implementation). >=20 > https://phabric.freebsd.org/D521 >=20 > Cheers, Seems reasonable to me. =97 Justin --Apple-Mail=_E8F869C3-89C8-4548-ADEE-570FA3BAEF62 Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=signature.asc Content-Type: application/pgp-signature; name=signature.asc Content-Description: Message signed with OpenPGP using GPGMail -----BEGIN PGP SIGNATURE----- Comment: GPGTools - http://gpgtools.org iQEcBAEBAgAGBQJT3JipAAoJED9n8CuvaSf4OrIIAIgaHjhkdbFyBf1gO7xIIeAj iV4Ylsv3spZtzF8S3QIpdKgQzCjA1FWcMnKE2DV7INWU5AnHU3vsw0UyCCefId1I nhru8VEh66L2YekUfDWPSydtJYdvhHI6oQFFh7hFjrBXgpBLdk4QwAP+IebegKYf 9DnukM4F508KldjedulqcIPPkzrXpArMxC4rFLtGXsYQGYZgM/R6Hj5mYFDFiZQB Tcf3mSE8/q9NrKiyZZFDKDdj6ta/kvLEopNiLR4d/K1fb7QBK6gVaLrNHRIZWRp5 dAJ8iFYPopj89AmyuX9eblT48lEIT7wScyyVvyi4LWGHdL0GUiCYWtTLMwtfM0U= =mJml -----END PGP SIGNATURE----- --Apple-Mail=_E8F869C3-89C8-4548-ADEE-570FA3BAEF62--