From mboxrd@z Thu Jan 1 00:00:00 1970 From: Doug Ledford Subject: Re: [PATCH] IB/ipoib: Change To max_cm_mtu when changing mode to connected Date: Tue, 09 Jun 2015 09:38:55 -0400 Message-ID: <1433857135.90034.13.camel@redhat.com> References: <1433673371-5355-1-git-send-email-erezsh@mellanox.com> <20150608164224.GA2499@obsidianresearch.com> <1433797482.90034.2.camel@redhat.com> Mime-Version: 1.0 Content-Type: multipart/signed; micalg="pgp-sha256"; protocol="application/pgp-signature"; boundary="=-MCfQb6fOegXSm7zPuT0O" Return-path: In-Reply-To: Sender: linux-rdma-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Erez Shitrit Cc: Jason Gunthorpe , Erez Shitrit , "linux-rdma-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" , Or Gerlitz , vlad-VPRAkNaXOzVWk0Htik3J/w@public.gmane.org, ELi Cohen List-Id: linux-rdma@vger.kernel.org --=-MCfQb6fOegXSm7zPuT0O Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable On Tue, 2015-06-09 at 09:06 +0300, Erez Shitrit wrote: > On Tue, Jun 9, 2015 at 12:04 AM, Doug Ledford wrote= : > > On Mon, 2015-06-08 at 10:42 -0600, Jason Gunthorpe wrote: > >> On Sun, Jun 07, 2015 at 01:36:11PM +0300, Erez Shitrit wrote: > >> > > >> > When switching between modes (datagram / connected) change the MTU > >> > accordingly. > >> > datagram mode up to 4K, connected mode up to (64K - 0x10). > >> > >> Is this a bug fix (describe the user visible impact)? Should it go to > >> -stable? Add a Fixes: line? > > > > I'm not sure I would call it a bug. Setting the MTU to max > > automatically is a policy decision more than anything else. Currently, > > you have to enable connected mode, then set the MTU. Both initscripts > > and NetworkManager do this for you on Red Hat, so the user sees no > > difference here. I can't speak to other OSes. I'm OK with setting >=20 > The only real reason for a user to switch to CM mode is for the > performance he can get, and this is only by the huge MTU the CM gives, > so it somehow should be part of the "mode setting". > As you said RH does it (in the new versions of its OS's only) No, we do it in all versions of our OS, but you have to set the MTU parameter, we don't default it to anything for you (but this is no different than setting CM). This is normal device setup. Just like we don't default Ethernet interfaces to jumbo frames, the user needs to set the MTU on that interface. And the user gets benefit at MTUs less than jumbo size. > via > scripting outside of the driver code, other vendor doesn't. >=20 > > connected mode MTU to max by default once we get the scatter/gather > > support for IPoIB added. >=20 > OK, great. Thanks. >=20 > > -- > > Doug Ledford > > GPG KeyID: 0E572FDD > > > -- > To unsubscribe from this list: send the line "unsubscribe linux-rdma" in > the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org > More majordomo info at http://vger.kernel.org/majordomo-info.html --=20 Doug Ledford GPG KeyID: 0E572FDD --=-MCfQb6fOegXSm7zPuT0O Content-Type: application/pgp-signature; name="signature.asc" Content-Description: This is a digitally signed message part Content-Transfer-Encoding: 7bit -----BEGIN PGP SIGNATURE----- Version: GnuPG v2 iQIcBAABCAAGBQJVduxvAAoJELgmozMOVy/d5pQQAIwMJh0U4p5ZsPdeWZpyKMEA wDZVMqz9oDaV7PfZMBBlKgSvJz4JLcdS98/KOtTC5Q2EIhXJnELfAQF+Jf1WnQnb sKhVHRAijduIHGOXbk8ALMREjhhYrIOMZprhV03pBxlsYPxau3TXXA6Eolj5K5pp 80xhi/E8VJVIuwu6yAyNRsGq/VISoZ8I6MJ2CNbeeVsatY1pB2T4ZNa/s1UaEyTX hbNQbm+fX7KsDGB/txLKElgS8Ku855jV4rxykHKmv0/cE+GicUIgLfehi4KVrb5G Bvia25CsbHvbi5F3XlZRsVW3MMOBzhumnULdNDOuxLUnGwPXgWDZyYq6lJfykV9d v5JnyCh+CC3U7MfK/pZUPjiZ1lqp1gc13qAEsoGrbIyZMiLtPbCnuGc1IrByiDfx Z0/N41oQxwvTUDClghMPySWKk1Ygrpk1fo19s98OZVtNSZESIyMPp7LQunOeO6/I X7DzjOBRwjydeXYAGQOp3WXn4QUzurfqPNnqS+IUKZPFqz0IwLqltLp8YVPnxele FGATCfBHtnAkjIymcDNCa6Gr+RywwrCgvN00dtN+hT0S7J8Q10/B3nteEhRueynL CkRYIK7FQ7n2C+zO1hJfEdWqpe8NwQ09viUiVK798YfzsEcFzbbidBGopAxqsQZD kEi/CXYNLdje0bmrkgeo =CcCy -----END PGP SIGNATURE----- --=-MCfQb6fOegXSm7zPuT0O-- -- To unsubscribe from this list: send the line "unsubscribe linux-rdma" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html