Date: Thu, 1 Mar 2012 16:15:53 +0200 From: Konstantin Belousov <kostikbel@gmail.com> To: Pawel Jakub Dawidek <pjd@FreeBSD.org> Cc: Attilio Rao <attilio@FreeBSD.org>, arch@FreeBSD.org, Gleb Kurtsou <gleb.kurtsou@gmail.com> Subject: Re: Prefaulting for i/o buffers Message-ID: <20120301141553.GT55074@deviant.kiev.zoral.com.ua> In-Reply-To: <20120301141247.GE1336@garage.freebsd.pl> References: <20120203193719.GB3283@deviant.kiev.zoral.com.ua> <CAJ-FndABi21GfcCRTZizCPc_Mnxm1EY271BiXcYt9SD_zXFpXw@mail.gmail.com> <20120225151334.GH1344@garage.freebsd.pl> <CAJ-FndBBKHrpB1MNJTXx8gkFXR2d-O6k5-HJeOAyv2DznpN-QQ@mail.gmail.com> <20120225194630.GI1344@garage.freebsd.pl> <20120301111624.GB30991@reks> <20120301141247.GE1336@garage.freebsd.pl>
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--nlOp58TzLcTjnOVc Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Thu, Mar 01, 2012 at 03:12:47PM +0100, Pawel Jakub Dawidek wrote: > On Thu, Mar 01, 2012 at 01:16:24PM +0200, Gleb Kurtsou wrote: > > On (25/02/2012 20:46), Pawel Jakub Dawidek wrote: > > > - "Every file system needs cache. Let's make it general, so that all = file > > > systems can use it!" Well, for VFS each file system is a separate > > > entity, which is not the case for ZFS. ZFS can cache one block only > > > once that is used by one file system, 10 clones and 100 snapshots, > > > which all are separate mount points from VFS perspective. > > > The same block would be cached 111 times by the buffer cache. > >=20 > > Hmm. But this one is optional. Use vop_cachedlookup (or call > > cache_entry() on your own), add a number of cache_prune calls. It's > > pretty much library-like design you describe below. >=20 > Yes, namecache is already library-like, but I was talking about the > buffer cache. I managed to bypass it eventually with suggestions from > ups@, but for a long time I was sure it isn't at all possible. I am quite curious, in which way buffer layer is mandatory ? --nlOp58TzLcTjnOVc Content-Type: application/pgp-signature Content-Disposition: inline -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.12 (FreeBSD) iEYEARECAAYFAk9PhJkACgkQC3+MBN1Mb4gPEACgz/9StyTUKFfToGQFVaUgJWpq SI8An0aCnA/fz8EySQ7u1IrO3JxLSIRr =4S1J -----END PGP SIGNATURE----- --nlOp58TzLcTjnOVc--
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