Hi all, I''ve got Xen 3.0 (stock as available on CentOS 5.6). I''m trying to use jumbo frames, but when Xen creates vifX.Y interfaces, it uses 1500. This brings the xenbrX bridges down to 1500, and effectively messes up anything thinking that it can use the larger packet size. So how can I make sure that all vifX.Y interfaces created by Xen are set to a given MTU? I''ve grepped the files under /etc/xen, but haven''t seen a specific place to set it. Thanks! -- Digimer E-Mail: digimer@alteeve.com AN!Whitepapers: http://alteeve.com Node Assassin: http://nodeassassin.org _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
Pasi Kärkkäinen
2011-Apr-15 10:12 UTC
Re: [Xen-users] Setting vifX.Y''s MTU automatically in Xen 3
On Wed, Apr 13, 2011 at 07:33:49AM -0400, Digimer wrote:> Hi all, > > I''ve got Xen 3.0 (stock as available on CentOS 5.6). I''m trying to use > jumbo frames, but when Xen creates vifX.Y interfaces, it uses 1500. This > brings the xenbrX bridges down to 1500, and effectively messes up > anything thinking that it can use the larger packet size. > > So how can I make sure that all vifX.Y interfaces created by Xen are > set to a given MTU? I''ve grepped the files under /etc/xen, but haven''t > seen a specific place to set it. > > Thanks! >I think first I''d try to modify vif-bridge script and make sure MTU of the vif is adjusted before attaching to the bridge. Verify you get that working, and then let''s figure out what''s the best way.. -- Pasi _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
Digimer
2011-Apr-15 11:28 UTC
Re: [Xen-users] Setting vifX.Y''s MTU automatically in Xen 3
On 04/15/2011 06:12 AM, Pasi Kärkkäinen wrote:> On Wed, Apr 13, 2011 at 07:33:49AM -0400, Digimer wrote: >> Hi all, >> >> I''ve got Xen 3.0 (stock as available on CentOS 5.6). I''m trying to use >> jumbo frames, but when Xen creates vifX.Y interfaces, it uses 1500. This >> brings the xenbrX bridges down to 1500, and effectively messes up >> anything thinking that it can use the larger packet size. >> >> So how can I make sure that all vifX.Y interfaces created by Xen are >> set to a given MTU? I''ve grepped the files under /etc/xen, but haven''t >> seen a specific place to set it. >> >> Thanks! >> > > I think first I''d try to modify vif-bridge script and make sure > MTU of the vif is adjusted before attaching to the bridge. > > Verify you get that working, and then let''s figure out what''s the best way.. > > -- PasiThis fails. I tried adding to ''vif-bridge'': ===case "$command" in online) setup_bridge_port "$vif" ifconfig $vif mtu 9000 add_to_bridge "$bridge" "$vif" ;; === Alternatively, I tried adding to ''xen-network-common.sh'': ===add_to_bridge () { local bridge=$1 local dev=$2 # Don''t add $dev to $bridge if it''s already on a bridge. if [ -e "/sys/class/net/${bridge}/brif/${dev}" ]; then ip link set ${dev} up || true return fi ifconfig ${dev} mtu 9000 brctl addif ${bridge} ${dev} ip link set ${dev} up } === Both cases caused the start of the domU to fail, complaining that the scripts failed. http://pastebin.com/xstkgYzx -- Digimer E-Mail: digimer@alteeve.com AN!Whitepapers: http://alteeve.com Node Assassin: http://nodeassassin.org _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
Pasi Kärkkäinen
2011-Apr-15 11:37 UTC
Re: [Xen-users] Setting vifX.Y''s MTU automatically in Xen 3
On Fri, Apr 15, 2011 at 07:28:00AM -0400, Digimer wrote:> On 04/15/2011 06:12 AM, Pasi Kärkkäinen wrote: > > On Wed, Apr 13, 2011 at 07:33:49AM -0400, Digimer wrote: > >> Hi all, > >> > >> I''ve got Xen 3.0 (stock as available on CentOS 5.6). I''m trying to use > >> jumbo frames, but when Xen creates vifX.Y interfaces, it uses 1500. This > >> brings the xenbrX bridges down to 1500, and effectively messes up > >> anything thinking that it can use the larger packet size. > >> > >> So how can I make sure that all vifX.Y interfaces created by Xen are > >> set to a given MTU? I''ve grepped the files under /etc/xen, but haven''t > >> seen a specific place to set it. > >> > >> Thanks! > >> > > > > I think first I''d try to modify vif-bridge script and make sure > > MTU of the vif is adjusted before attaching to the bridge. > > > > Verify you get that working, and then let''s figure out what''s the best way.. > > > > -- Pasi > > This fails. I tried adding to ''vif-bridge'': > > ===> case "$command" in > online) > setup_bridge_port "$vif" > ifconfig $vif mtu 9000Try doing it before setup_bridge_port ? Do you need to specify a patch for ifconfig?> add_to_bridge "$bridge" "$vif" > ;; > ===> > Alternatively, I tried adding to ''xen-network-common.sh'': > > ===> add_to_bridge () { > local bridge=$1 > local dev=$2 > > # Don''t add $dev to $bridge if it''s already on a bridge. > if [ -e "/sys/class/net/${bridge}/brif/${dev}" ]; then > ip link set ${dev} up || true > return > fi > ifconfig ${dev} mtu 9000 > brctl addif ${bridge} ${dev} > ip link set ${dev} up > } > ===> > Both cases caused the start of the domU to fail, complaining that the > scripts failed. >Well something goes wrong then..> http://pastebin.com/xstkgYzx >-- Pasi _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
Digimer
2011-Apr-15 13:13 UTC
Re: [Xen-users] Setting vifX.Y''s MTU automatically in Xen 3
On 04/15/2011 07:37 AM, Pasi Kärkkäinen wrote:> Try doing it before setup_bridge_port ?Didn''t help.> Do you need to specify a patch for ifconfig?What patch might that be?> Well something goes wrong then..Heh, yup. :) -- Digimer E-Mail: digimer@alteeve.com AN!Whitepapers: http://alteeve.com Node Assassin: http://nodeassassin.org _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
Pasi Kärkkäinen
2011-Apr-15 13:41 UTC
Re: [Xen-users] Setting vifX.Y''s MTU automatically in Xen 3
On Fri, Apr 15, 2011 at 09:13:14AM -0400, Digimer wrote:> On 04/15/2011 07:37 AM, Pasi Kärkkäinen wrote: > > Try doing it before setup_bridge_port ? > > Didn''t help. >Ok.> > Do you need to specify a patch for ifconfig? > > What patch might that be? >Erm.. I meant ''path'', not ''patch'' :)> > Well something goes wrong then.. > > Heh, yup. :) >On mailinglist archive I''ve seen people using jumbo frames with domUs.. so it''s definitely doable. -- Pasi _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
Pasi Kärkkäinen
2011-Apr-15 18:03 UTC
Re: [Xen-users] Setting vifX.Y''s MTU automatically in Xen 3
On Fri, Apr 15, 2011 at 04:41:02PM +0300, Pasi Kärkkäinen wrote:> On Fri, Apr 15, 2011 at 09:13:14AM -0400, Digimer wrote: > > On 04/15/2011 07:37 AM, Pasi Kärkkäinen wrote: > > > Try doing it before setup_bridge_port ? > > > > Didn''t help. > > > > Ok. > > > > Do you need to specify a patch for ifconfig? > > > > What patch might that be? > > > > Erm.. I meant ''path'', not ''patch'' :) > > > > Well something goes wrong then.. > > > > Heh, yup. :) > > > > On mailinglist archive I''ve seen people using jumbo frames with domUs.. > so it''s definitely doable. >Ok, followup for the list archives.. pvops 2.6.32.x dom0 kernel contains this patch since February 2010: "xen/netback: Allow setting of large MTU before rings have connected": https://git.kernel.org/?p=linux/kernel/git/jeremy/xen.git;a=commitdiff;h=bee2eec2355c4bf4e149a426d5e30527162de566 So changing vif mtu to 9000 before attaching to the bridge works when using pvops 2.6.32 dom0 kernel. Patch for 2.6.18 kernel here: http://lists.xensource.com/archives/html/xen-devel/2011-02/msg00413.html Redhat RHEL5 bugzilla entry for adding that patch to el5 kernel-xen dom0 netback: https://bugzilla.redhat.com/show_bug.cgi?id=697021 -- Pasi _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users