From owner-freebsd-hackers@FreeBSD.ORG Fri Sep 18 07:40:55 2009 Return-Path: Delivered-To: freebsd-hackers@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 464DC106566B for ; Fri, 18 Sep 2009 07:40:55 +0000 (UTC) (envelope-from kostikbel@gmail.com) Received: from mail.zoral.com.ua (skuns.zoral.com.ua [91.193.166.194]) by mx1.freebsd.org (Postfix) with ESMTP id BA57F8FC1F for ; Fri, 18 Sep 2009 07:40:54 +0000 (UTC) Received: from deviant.kiev.zoral.com.ua (root@deviant.kiev.zoral.com.ua [10.1.1.148]) by mail.zoral.com.ua (8.14.2/8.14.2) with ESMTP id n8I7eR0h046250 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO); Fri, 18 Sep 2009 10:40:28 +0300 (EEST) (envelope-from kostikbel@gmail.com) Received: from deviant.kiev.zoral.com.ua (kostik@localhost [127.0.0.1]) by deviant.kiev.zoral.com.ua (8.14.3/8.14.3) with ESMTP id n8I7eRp8077333; Fri, 18 Sep 2009 10:40:27 +0300 (EEST) (envelope-from kostikbel@gmail.com) Received: (from kostik@localhost) by deviant.kiev.zoral.com.ua (8.14.3/8.14.3/Submit) id n8I7eRvY077332; Fri, 18 Sep 2009 10:40:27 +0300 (EEST) (envelope-from kostikbel@gmail.com) X-Authentication-Warning: deviant.kiev.zoral.com.ua: kostik set sender to kostikbel@gmail.com using -f Date: Fri, 18 Sep 2009 10:40:27 +0300 From: Kostik Belousov To: d@delphij.net Message-ID: <20090918074027.GI47688@deviant.kiev.zoral.com.ua> References: <20090917101526.GF57619@rambler-co.ru> <4AB2B7A1.5000601@delphij.net> Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="iWiB/3aOFpG2Ko/s" Content-Disposition: inline In-Reply-To: <4AB2B7A1.5000601@delphij.net> User-Agent: Mutt/1.4.2.3i X-Virus-Scanned: clamav-milter 0.95.2 at skuns.kiev.zoral.com.ua X-Virus-Status: Clean X-Spam-Status: No, score=-4.4 required=5.0 tests=ALL_TRUSTED,AWL,BAYES_00 autolearn=ham version=3.2.5 X-Spam-Checker-Version: SpamAssassin 3.2.5 (2008-06-10) on skuns.kiev.zoral.com.ua Cc: freebsd-hackers@freebsd.org Subject: Re: fcntl(F_RDAHEAD) X-BeenThere: freebsd-hackers@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Technical Discussions relating to FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 18 Sep 2009 07:40:55 -0000 --iWiB/3aOFpG2Ko/s Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Thu, Sep 17, 2009 at 03:26:41PM -0700, Xin LI wrote: > -----BEGIN PGP SIGNED MESSAGE----- > Hash: SHA1 >=20 > Hi, Igor, >=20 > Igor Sysoev wrote: > > Hi, > >=20 > > nginx-0.8.15 can use completely non-blocking sendfile() using SF_NODISK= IO > > flag. When sendfile() returns EBUSY, nginx calls aio_read() to read sin= gle > > byte. The first aio_read() preloads the first 128K part of a file in VM= cache, > > however, all successive aio_read()s preload just 16K parts of the file. > > This makes non-blocking sendfile() usage ineffective for files larger > > than 128K. > >=20 > > I've created a small patch for Darwin compatible F_RDAHEAD fcntl: > >=20 > > fcntl(fd, F_RDAHEAD, preload_size) > >=20 > > There is small incompatibilty: Darwin's fcntl allows just to enable/dis= able > > read ahead, while the proposed patch allows to set exact preload size. > >=20 > > Currently the preload size affects vn_read() code path only and does not > > affect on sendfile() code path. However, it can be easy extended on > > sendfile() part too. The preload size is still limited by sysctl vfs.re= ad_max. > >=20 > > The patch is against FreeBSD 7.2 and was tested on FreeBSD 7.2-STABLE o= nly. >=20 > I have ported this as a patch against -HEAD (should apply on 8.0-R but > it's too late for us to add a new feature) plus a manual page entry > documenting the feature. >=20 > I've used F_READAHEAD as the name, but reading the manual page, it looks > like we can just use F_RDAHEAD since Darwin seems to just distinguish 0 > and !=3D0 case so that programmers won't have to use #ifdef or something > else to get code working on different platform? What I dislike about the patch is the new kernel-private flag that is eaten from the open(2) flags namespace. We do already have FHASLOCK, so far the only such flag. --iWiB/3aOFpG2Ko/s Content-Type: application/pgp-signature Content-Disposition: inline -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.10 (FreeBSD) iEYEARECAAYFAkqzOWsACgkQC3+MBN1Mb4jncwCg9zvfscnUBgH4Jsu1g/vRDRaJ En4An1ZLbdjiRLaEOqhvEUmRoCrP8pq3 =mP+3 -----END PGP SIGNATURE----- --iWiB/3aOFpG2Ko/s--