Date: Wed, 3 Sep 2008 15:25:12 +0400 From: Igor Sysoev <is@rambler-co.ru> To: Sujit Karataparambil <sjt.kar@gmail.com> Cc: freebsd-stable@freebsd.org Subject: Re: vfs.ffs.rawreadahead Message-ID: <20080903112512.GB62541@rambler-co.ru> In-Reply-To: <921ca19c0809030333u6accf415l80ec5bfb4a984ce1@mail.gmail.com> References: <20080903095352.GA62541@rambler-co.ru> <921ca19c0809030333u6accf415l80ec5bfb4a984ce1@mail.gmail.com>
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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 <is@rambler-co.ru> 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/
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