From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:56158) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1WzBQc-00036Q-3h for qemu-devel@nongnu.org; Mon, 23 Jun 2014 17:05:30 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1WzBQX-0004rm-O1 for qemu-devel@nongnu.org; Mon, 23 Jun 2014 17:05:26 -0400 Received: from mx1.redhat.com ([209.132.183.28]:22897) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1WzBQX-0004rX-Fc for qemu-devel@nongnu.org; Mon, 23 Jun 2014 17:05:21 -0400 Message-ID: <53A89683.4030707@redhat.com> Date: Mon, 23 Jun 2014 15:05:07 -0600 From: Eric Blake MIME-Version: 1.0 References: <1403533836-28589-1-git-send-email-pl@kamp.de> <53A84391.7040904@redhat.com> <439D6F63-2D86-4ABC-9796-4298179201AB@kamp.de> In-Reply-To: <439D6F63-2D86-4ABC-9796-4298179201AB@kamp.de> Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="Nt7NnTV7ghc03WI17P9bRUTTia2Qhwe51" Subject: Re: [Qemu-devel] [PATCH] block/nfs: add knob to set readahead List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Peter Lieven Cc: kwolf@redhat.com, pbonzini@redhat.com, stefanha@redhat.com, qemu-devel@nongnu.org, ronniesahlberg@gmail.com This is an OpenPGP/MIME signed message (RFC 4880 and 3156) --Nt7NnTV7ghc03WI17P9bRUTTia2Qhwe51 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable On 06/23/2014 02:47 PM, Peter Lieven wrote: >>> +#ifdef LIBNFS_FEATURE_READAHEAD >>> + } else if (!strcmp(qp->p[i].name, "readahead")) { >>> + nfs_set_readahead(client->context, atoi(qp->p[i].value))= ; >>> +#endif >> >> I'm not a fan of adding even more special-casing to the file-name URI >> without also adding it to the QAPI schema for use in the blockdev-add >> command. Of course, we don't have structured nfs options for >> blockdev-add yet, but maybe it's time to start thinking about that >> addition before we do this addition. >=20 > I would like to leave this for a follow-up and I promise to take care o= f this. > If you could give me a pointer of an existing driver that does this as = a reference > I would be grateful. A good example of a recent conversion to structured options would be the blkdebug and blkverify backends (look around commit 1bf20b82), or proposed addition of new backends (such as archipelego, https://lists.gnu.org/archive/html/qemu-devel/2014-06/msg05309.html). It may be a bigger task than you anticipate, and certainly won't make the 2.1 timeframe, but it's worth doing so if you're up to the task, more power to you :) >=20 > For the read ahead parameter its likely not needed as (at least in my u= se case) > the read ahead makes only sense when converting a compressed QCOW2 Temp= late File > which lives on an NFS Share to a RAW Device. So I use it with qemu-img.= > For a Container File that is used as a VM hard drive I would likely not= use read ahead > as the operating system itself will implement some sort of read ahead a= lready. Even if qemu-img is likely to be the only one ever specifying the option, it still makes sense to expose it via QMP, as we are gradually trying to move qemu-img over to more exclusive use of QMP (or at least the underlying functions reached by QMP) rather than ad-hoc code. For example, https://lists.gnu.org/archive/html/qemu-devel/2014-06/msg01822.html). --=20 Eric Blake eblake redhat com +1-919-301-3266 Libvirt virtualization library http://libvirt.org --Nt7NnTV7ghc03WI17P9bRUTTia2Qhwe51 Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- Version: GnuPG v1 Comment: Public key at http://people.redhat.com/eblake/eblake.gpg Comment: Using GnuPG with Thunderbird - http://www.enigmail.net/ iQEcBAEBCAAGBQJTqJaDAAoJEKeha0olJ0NqxSkH/ipkm0s4F78Vnx0vSgZz1FQ5 0oHDWqEdKDzbjlN+zGslyOoaDrzagIjnlVOB0aTToneqLZTQDRypa5emXP2PmeS+ YioukUKy54WC8EwbGcjLSqzt6X22/WmHaGfRhWfcP5b91ujri87dS0g54FE+8ty6 YVZ8nxR2Uo2cnxE8A4bGHlUb4McjJafoB7tJyr2OCO78TByfWVyRTUBkN/pTuPew R0rwSpDMMrrVmsKU5d/x8FJ21fGKsOla/IDh2TvPoXUeRPp4clXB5vTFxDWGq047 pj6uibVwSXTGlmnv4c4LWCWYvUBri85PZl6GVSv98IkgExuabUuV5lIykUrVys0= =9E8C -----END PGP SIGNATURE----- --Nt7NnTV7ghc03WI17P9bRUTTia2Qhwe51--