From owner-freebsd-fs@FreeBSD.ORG Wed Feb 15 14:02:19 2012 Return-Path: Delivered-To: freebsd-fs@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 1CB59106564A for ; Wed, 15 Feb 2012 14:02:19 +0000 (UTC) (envelope-from freebsd-fs@m.gmane.org) Received: from plane.gmane.org (plane.gmane.org [80.91.229.3]) by mx1.freebsd.org (Postfix) with ESMTP id C12168FC1D for ; Wed, 15 Feb 2012 14:02:18 +0000 (UTC) Received: from list by plane.gmane.org with local (Exim 4.69) (envelope-from ) id 1RxfR2-0007NQ-F3 for freebsd-fs@freebsd.org; Wed, 15 Feb 2012 15:02:16 +0100 Received: from lara.cc.fer.hr ([161.53.72.113]) by main.gmane.org with esmtp (Gmexim 0.1 (Debian)) id 1AlnuQ-0007hv-00 for ; Wed, 15 Feb 2012 15:02:16 +0100 Received: from ivoras by lara.cc.fer.hr with local (Gmexim 0.1 (Debian)) id 1AlnuQ-0007hv-00 for ; Wed, 15 Feb 2012 15:02:16 +0100 X-Injected-Via-Gmane: http://gmane.org/ To: freebsd-fs@freebsd.org From: Ivan Voras Date: Wed, 15 Feb 2012 15:02:06 +0100 Lines: 40 Message-ID: References: <15861.1329298812.1414986334451204096@ffe12.ukr.net> <92617.1329301696.6338962447434776576@ffe5.ukr.net> <96280.1329309582.18313701080496209920@ffe5.ukr.net> Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="------------enigEFAF81B6357F075B35F57CCB" X-Complaints-To: usenet@dough.gmane.org X-Gmane-NNTP-Posting-Host: lara.cc.fer.hr User-Agent: Mozilla/5.0 (X11; FreeBSD amd64; rv:10.0) Gecko/20120213 Thunderbird/10.0 In-Reply-To: <96280.1329309582.18313701080496209920@ffe5.ukr.net> X-Enigmail-Version: 1.3.5 Subject: Re: ZFS and mem management X-BeenThere: freebsd-fs@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Filesystems List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 15 Feb 2012 14:02:19 -0000 This is an OpenPGP/MIME signed message (RFC 2440 and 3156) --------------enigEFAF81B6357F075B35F57CCB Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable On 15/02/2012 13:39, Pavlo wrote: >=20 >=20 >=20 > Unfortunately we can't afford disabling prefetch. It is too much of an > overhead. >=20 > Also I made some tests. I have process that maps file using mmap() and > writes or reads first byte of each page of mapped file with some data. Note that ZFS is designed so that it interacts somewhat badly with mmap() and other kernel services which rely on coherency between VM and IO such as sendfile(). At the very best, you will have two in-kernel copies of all data buffers used with such interfaces, but there have been sporadic reports that there are other bugs with it. If you have a test server, I'd recommend you do the same test on UFS for comparison. --------------enigEFAF81B6357F075B35F57CCB Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.18 (FreeBSD) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org/ iEYEARECAAYFAk87ut4ACgkQldnAQVacBcjuBQCg1GDudjWQbtYC/SbAsepeYOnH gD4AnitS65MVKbGBkXGfjYb7ZpOSsKi9 =fEBM -----END PGP SIGNATURE----- --------------enigEFAF81B6357F075B35F57CCB--