Bug 733416
Summary: | netfront MTU drops to 1500 after domain migration | |||
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Product: | Red Hat Enterprise Linux 5 | Reporter: | Paolo Bonzini <pbonzini> | |
Component: | kernel-xen | Assignee: | Paolo Bonzini <pbonzini> | |
Status: | CLOSED ERRATA | QA Contact: | Virtualization Bugs <virt-bugs> | |
Severity: | high | Docs Contact: | ||
Priority: | high | |||
Version: | 5.6 | CC: | dhoward, drjones, jzheng, leiwang, lersek, mrezanin, pasik, pbonzini, plyons, qguan, qwan, xen-maint, yuzhang | |
Target Milestone: | rc | Keywords: | ZStream | |
Target Release: | --- | |||
Hardware: | All | |||
OS: | Linux | |||
Whiteboard: | ||||
Fixed In Version: | kernel-2.6.18-284.el5 | Doc Type: | Bug Fix | |
Doc Text: |
This update introduces support for jumbo frames in the Xen networking backend. However, old guests will still revert to a 1500-byte MTU after migration. This update also changes how the guest will probe the backend's Scatter/Gather I/O functionality. As long as a recent enough kernel is installed in the destination host, this will ensure that the guest will keep a large MTU even after migration.
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Story Points: | --- | |
Clone Of: | 697021 | |||
: | 733651 (view as bug list) | Environment: | ||
Last Closed: | 2012-02-21 03:53:40 UTC | Type: | --- | |
Regression: | --- | Mount Type: | --- | |
Documentation: | --- | CRM: | ||
Verified Versions: | Category: | --- | ||
oVirt Team: | --- | RHEL 7.3 requirements from Atomic Host: | ||
Cloudforms Team: | --- | Target Upstream Version: | ||
Embargoed: | ||||
Bug Depends On: | 697021, 720347 | |||
Bug Blocks: | 514489, 738392 |
Description
Paolo Bonzini
2011-08-25 16:27:01 UTC
This request was evaluated by Red Hat Product Management for inclusion in a Red Hat Enterprise Linux maintenance release. Product Management has requested further review of this request by Red Hat Engineering, for potential inclusion in a Red Hat Enterprise Linux Update release for currently deployed products. This request is not yet committed for inclusion in an Update release. > - on both machines, ensure the Xen bridge has its MTU set to 9000, for example > by adding this (huge hack) to /etc/init.d/xend at the end of function > await_daemons_up > > sleep 5 > ip link set mtu 9000 dev vif0.1 > ip link set mtu 9000 dev peth0 > ip link set mtu 9000 dev xenbr0 This is not necessary if you have the patch for bug 733417. Patch(es) available in kernel-2.6.18-284.el5 You can download this test kernel (or newer) from http://people.redhat.com/jwilson/el5 Detailed testing feedback is always welcomed. Patch(es) available in kernel-2.6.18-284.el5 You can download this test kernel (or newer) from http://people.redhat.com/jwilson/el5 Detailed testing feedback is always welcomed. Technical note added. If any revisions are required, please edit the "Technical Notes" field accordingly. All revisions will be proofread by the Engineering Content Services team. New Contents: This update introduces support for jumbo frames in the Xen networking backend. However, old guests will still revert to a 1500-byte MTU after migration. This update also changes how the guest will probe the backend's Scatter/Gather I/O functionality. As long as a recent enough kernel is installed in the destination host, this will ensure that the guest will keep a large MTU even after migration. Tested with the same steps as bug 738608 comment 6, host is kernel-xen-2.6.18-297.el5 x86_64. Guest is RHEL5.8 20111030.0 i386 and x86_64 PV DomU (kernel-xen-2.6.18-294.el5), the netfront device keeps the MTU=9000 configuration after guest migration, so the fix works well. Change this bug to VERIFIED. (In reply to comment #11) > Tested with the same steps as bug 738608 comment 6, host is > kernel-xen-2.6.18-297.el5 x86_64. Guest is RHEL5.8 20111030.0 i386 and x86_64 > PV DomU (kernel-xen-2.6.18-294.el5), the netfront device keeps the MTU=9000 > configuration after guest migration, so the fix works well. Change this bug to > VERIFIED. Xen userspace is xen-3.0.3-135.el5 which has the userspace fix (bug 733417) included. Since the problem described in this bug report should be resolved in a recent advisory, it has been closed with a resolution of ERRATA. For information on the advisory, and where to find the updated files, follow the link below. If the solution does not work for you, open a new bug report. http://rhn.redhat.com/errata/RHSA-2012-0150.html |