Date: Wed, 15 Feb 2012 15:02:06 +0100 From: Ivan Voras <ivoras@freebsd.org> To: freebsd-fs@freebsd.org Subject: Re: ZFS and mem management Message-ID: <jhgdsu$k7l$1@dough.gmane.org> In-Reply-To: <96280.1329309582.18313701080496209920@ffe5.ukr.net> References: <15861.1329298812.1414986334451204096@ffe12.ukr.net> <92617.1329301696.6338962447434776576@ffe5.ukr.net> <CA%2BdUSyqKoqrfD_cgsfupsuZRE0O6dH-4F1roLp_GFaeBKJkN-w@mail.gmail.com> <CA%2BdUSyoRyC5O4D8tQQ9iDH2E87P3cxW_Ay8b6FuvzzbORpSYhA@mail.gmail.com> <96280.1329309582.18313701080496209920@ffe5.ukr.net>
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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--
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