From owner-freebsd-stable@FreeBSD.ORG Wed Sep 3 11:33:22 2008 Return-Path: Delivered-To: freebsd-stable@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id AB057106564A for ; Wed, 3 Sep 2008 11:33:22 +0000 (UTC) (envelope-from sjt.kar@gmail.com) Received: from yx-out-2324.google.com (yx-out-2324.google.com [74.125.44.28]) by mx1.freebsd.org (Postfix) with ESMTP id 5E8F58FC0A for ; Wed, 3 Sep 2008 11:33:22 +0000 (UTC) (envelope-from sjt.kar@gmail.com) Received: by yx-out-2324.google.com with SMTP id 8so1521429yxb.13 for ; Wed, 03 Sep 2008 04:33:21 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=domainkey-signature:received:received:message-id:date:from:subject :cc:in-reply-to:mime-version:content-type:content-transfer-encoding :content-disposition:references; bh=SwfeVj2wS9HYv9mRYvwrL1NsopAhUidQ7vzO7z2t72w=; b=rfO/mO73zcHBuxMkmS7XLRkR2NPy2yQrEZl49Tn107I+GvvYbuSpqtVIVgoktgNvEQ EmOusgdf6qUQPb5gRd3/DgXtZgw5YJ9WOjJSWojErUtKj7LNtwiwpWrIKlkx9hR1I6pR IyUNIu/XE8KakTY9YpsE+DAXYwWD1vA7YqnGI= DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=message-id:date:from:subject:cc:in-reply-to:mime-version :content-type:content-transfer-encoding:content-disposition :references; b=Ctp3d77SN6lQHMMCMb8Kzo4SqrIXqSVHJtrKhlk6OSixGm0f0NUiqRHwvabteJc4IL G1N6NUIqBjHU1hXhmQIORCKqcHFp8Mr2DgnGxyslAPPDkYeuVpwhtxUjJWAYQTmsDNQb aL9jMYAwVsA/co4I7i88bqO5LTh91jePiai2w= Received: by 10.150.98.18 with SMTP id v18mr12235115ybb.94.1220441601609; Wed, 03 Sep 2008 04:33:21 -0700 (PDT) Received: by 10.151.78.4 with HTTP; Wed, 3 Sep 2008 04:33:21 -0700 (PDT) Message-ID: <921ca19c0809030433w50e16100rd624cdb4a2e4e947@mail.gmail.com> Date: Wed, 3 Sep 2008 17:03:21 +0530 From: "Sujit Karataparambil" Cc: freebsd-stable@freebsd.org In-Reply-To: <20080903112512.GB62541@rambler-co.ru> MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Content-Disposition: inline References: <20080903095352.GA62541@rambler-co.ru> <921ca19c0809030333u6accf415l80ec5bfb4a984ce1@mail.gmail.com> <20080903112512.GB62541@rambler-co.ru> Subject: Re: vfs.ffs.rawreadahead X-BeenThere: freebsd-stable@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Production branch of FreeBSD source code List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 03 Sep 2008 11:33:22 -0000 These are Journalling File System. Some thing like WAPBL which stands for Write-Ahead Physical Block Logging. These are built on Generic kernel components. On 9/3/08, Igor Sysoev wrote: > On Wed, Sep 03, 2008 at 04:03:59PM +0530, Sujit Karataparambil wrote: > > > The VFS was designed to be Object abtraction of the Berkeley Fast File System. > > This has been since an terminology with journalling filesystem to have > > functionality to added on request. > > In src/sys/ufs/ffs/ffs_rawread.c I see that rawreadahead is used. > However, I do not understand whether rawreadahead starts a second > parallel ahead disk transaction with supplied userland buffer or not. > > > -- > Igor Sysoev > http://sysoev.ru/en/ > > > On 9/3/08, Igor Sysoev wrote: > > > Hi, > > > > > > could anyone tell what does vfs.ffs.rawreadahead enable ? > > > As I understand it's used in DIRECTIO code that allows read data > > > directly to an userland buffer bypassing the buffer cache. > > > What I can not understand where the read ahead data can be placed in ? > > > > > > > > > -- > > > Igor Sysoev > > > http://sysoev.ru/en/ > -- --linux(2.4/2.6),bsd(4.5.x+),solaris(2.5+)