Skip site navigation (1)Skip section navigation (2)
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>

next in thread | previous in thread | raw e-mail | index | archive | help
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--




Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?jhgdsu$k7l$1>