From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:55564) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZUz7W-0006es-NC for qemu-devel@nongnu.org; Thu, 27 Aug 2015 11:29:43 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1ZUz7V-000148-Oq for qemu-devel@nongnu.org; Thu, 27 Aug 2015 11:29:42 -0400 References: From: Eric Blake Message-ID: <55DF2CDA.1070609@redhat.com> Date: Thu, 27 Aug 2015 09:29:30 -0600 MIME-Version: 1.0 In-Reply-To: Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="GHNcXmlk8gVifNBKTelbL1GCvjSpJpmjv" Subject: Re: [Qemu-devel] hd-geo-test creates 4GB files on FSes that don't support sparse images, doesn't delete them on error List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Peter Maydell , QEMU Developers Cc: John Snow , Markus Armbruster , Qemu-block This is an OpenPGP/MIME signed message (RFC 4880 and 3156) --GHNcXmlk8gVifNBKTelbL1GCvjSpJpmjv Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable On 08/27/2015 09:17 AM, Peter Maydell wrote: > I've noticed recently that tests/hd-geo-test.c creates test disk > images which are 4GB in size, which is a problem if the filesystem > on the host doesn't support sparse files. In particular, OSX's HFS+ > doesn't have sparse file support, and Windows probably doesn't either. Windows NTFS supports sparse files (minimum hole size of 64k), but it can be a pain to set up, and while it saves disk space, it may actually slow your program down. [At one point cygwin created sparse files on windows by default, but because it was demonstrated to hurt performance in dealing with sparse files, because Windows doesn't handle sparse files efficiently, the cygwin defaults were switched so that it now requires an explicit opt-in mount option before even attempting sparse files] > Worse, if the test fails an assertion somewhere the test doesn't > clean up after itself and leaves a 4GB file lying around in /tmp/. >=20 > It would be nice if we could skip these tests on filesystems that > don't have sparse file support... Or even where sparse files are supported but not default. --=20 Eric Blake eblake redhat com +1-919-301-3266 Libvirt virtualization library http://libvirt.org --GHNcXmlk8gVifNBKTelbL1GCvjSpJpmjv 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 Comment: Public key at http://people.redhat.com/eblake/eblake.gpg Comment: Using GnuPG with Thunderbird - http://www.enigmail.net/ iQEcBAEBCAAGBQJV3yzaAAoJEKeha0olJ0NqlU0H+wVkT4FbwRvVrKo4+Q9pb75H sVUOQkxlOBkpbKHtxRpeoi7UeyWRvCcPFIt2lpivPnfpYbQb29AASxoHlXwuAIwc LgQJJSzbaVHuE70EOXPUvOOyAtfZR6heUcdj2XdYXxE3hmxw7DFzuKMSJH1x8dBh 68k9WPmr3KVox8ybJDKPaRSWvt/sS79v09laGobMnL7Dy9gU0myhD1Ah7dx+fp9D nIQ98YkpXNRsdctryR3B1oc6pxBEdKNG+Q2ZxiLJttXVg+IxP05FIvsNmARj+N43 FISC2eEd8pn0isdMCjogf4Q9G0trysTSSY/oeyL+kLPbavSVNIHue6jQYdrpE1M= =AboT -----END PGP SIGNATURE----- --GHNcXmlk8gVifNBKTelbL1GCvjSpJpmjv--