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micalg=pgp-sha512; protocol="application/pgp-signature"; boundary="m1R7U2xm5hsa22/E" Content-Disposition: inline In-Reply-To: --m1R7U2xm5hsa22/E Content-Type: text/plain; protected-headers=v1; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: quoted-printable Date: Thu, 18 Aug 2022 10:24:01 -0400 From: Demi Marie Obenour To: Jan Beulich Cc: Wei Liu , Anthony PERARD , Marek =?utf-8?Q?Marczykowski-G=C3=B3recki?= , Xen developer discussion Subject: Re: [PATCH] Use direct I/O for loop devices On Thu, Aug 18, 2022 at 04:12:10PM +0200, Jan Beulich wrote: > On 18.08.2022 16:04, Demi Marie Obenour wrote: > > On Thu, Aug 18, 2022 at 09:02:11AM +0200, Jan Beulich wrote: > >> On 17.08.2022 22:46, Demi Marie Obenour wrote: > >>> --- a/tools/hotplug/Linux/block > >>> +++ b/tools/hotplug/Linux/block > >>> @@ -330,7 +330,7 @@ mount it read-write in a guest domain." > >>> else > >>> roflag=3D'' > >>> fi > >>> - do_or_die losetup $roflag "$loopdev" "$file" > >>> + do_or_die losetup --direct-io=3Don $roflag "$loopdev" "$file" > >> > >> I guess you want to first check (maybe in tools/configure) that losetup > >> actually supports that option. The old-ish one I'm looking at doesn't, > >> according to its --help output at least. > >=20 > > What version are you referring to? >=20 > The tool itself doesn't recognize --version. It originates from > util-linux 2.19.1 from all I can tell. I see. Qubes OS doesn=E2=80=99t need to support such old versions. Are you referring to=20 > > In Qubes OS the current plan is to use a block =E2=80=9Cscript=E2=80=9D= written in C, to > > improve performance and (when combined with kernel patches) eliminate > > race conditions. This code could be made a wrapper for the C version. >=20 > Is this relevant here in some way I don't recognize, or did you say this > only to provide some further background info? If the C code becomes part of the toolstack it would avoid needing to call into losetup. --=20 Sincerely, Demi Marie Obenour (she/her/hers) Invisible Things Lab --m1R7U2xm5hsa22/E Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQIzBAEBCgAdFiEEdodNnxM2uiJZBxxxsoi1X/+cIsEFAmL+S5QACgkQsoi1X/+c IsESWQ/9HP38OLGHK24PUlxDPb3xI4k5IkCcCRNjO9zhERgHWFZPDxEVN40AAj1V JdcABEkEw+Y3JZ14oOU2/RDEpYVJfJV3bchamiYq+vnOu72NZaQz04FrOo/we1vH a6jXHe9H8ncZmd6RmQnK+ViFh6s9JsBRZ8h1nNrNjKcoNphhnwtIMYIUMRrRicIb qFjXEVULEAyR4e5peF1mxwbQ/sFMB1gArot03S5DGwfUw9o4mS9kIGrL0eX3n5MH uGr7lJzl8hPwnTUtl6x+eYCXEVanQ3AeKsTykYsB8uOwp1ED1F9DAl+LQK/MqNXq AH6O1vcw0QI2xLuLVT+H4mxkE0AeIjcQwwpkxJCvXtsI7w/C+lQjQyFSz9WTTYT2 +5c/JGF3U4naa/TRkXAx7vOFW/9O19VrhkHs3HrrbnPsPl36wG9quwUNA8bA2pXG 9F6kkALzU03Lw8HIR3cnPQGRnJXurJ6utjvToSPE7mMrIB4s1iEnTXd2PtAZc+eI JrXsdIDHMJtXqLZmKU9a+N3ixdKr2Pf4wIqR4Lz2Owa+tWJJeAdU15MI4zZujOto L+9t5W1YYIxFV2MwRq7epg9T3WDRVnsPF3Oa2F+9yw539bj41cfixqUawbycvHOt wXzbGGl4htiXAFadv4WnH8n21fMQP5oSKyFi+1mZ6u0kMepSeoA= =UMum -----END PGP SIGNATURE----- --m1R7U2xm5hsa22/E--