** Changed in: linux (Ubuntu Jammy)
Status: In Progress => Fix Committed
** Changed in: linux (Ubuntu Kinetic)
Status: In Progress => Fix Committed
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https://bugs.launchpad.net/bugs/2012335
Title:
Ubuntu 22.04 raise abnormal NIC MSI-X requests with larger CPU cores
(256)
Status in linux package in Ubuntu:
Fix Released
Status in linux source package in Jammy:
Fix Committed
Status in linux source package in Kinetic:
Fix Committed
Bug description:
SRU Justification:
[Impact]
There is a user reporting errors in setup with their Intel E810 NIC with
error messages saying that the driver cannot allocate enough MSI-X vectors
on their 256 cpu-count system.
It seems the ICE ethernet driver has an all or nothing approach to
allocating MSI-X vectors and could request more MSI-X vectors than it
finds available, which could lead to the driver failing to initialize and
start.
[Fix]
The patch that fixes this allocates as many MSI-X vectors as it can to
continue
functionality by reducing the number of requested MSI-X vectors if it does
not have enough to do full allocation.
[Backport]
In Jammy we do not carry patches for switchdev support in the driver so do not
allocate the switchdev MSI-X vector for it. Also in Jammy use the older
way of checking RDMA support by testing the RDMA bit is set as opposed to the
newer
ice_is_rdma_ena that the patch uses.
[Test Plan]
Install and startup Ice driver with an Intel 800 series NIC and check that we
do not have the failure:
Not enough device MSI-X vectors, requested = 260, available = 253
and check that everything works as expected.
The backported patch for Jammy has been tested by the original user who
submited the bug report with their high cpu count system and confirmed no
errors.
[Where problems could occur]
There could be problems with the logic of reducing the MSI-X vector
usage leading to more errors in the driver, but otherwise minimal
regression potential as the code is mostly refactoring initial MSI-X
setup.
----------------------------------
System Configuration
OS: Ubuntu 22.04 LTS
Kernel: 5.15.0-25-generic
CPUs: 256
NIC: Intel E810 NIC with 512 MSIx vectors each function
Errors
Not enough device MSI-X vectors, requested = 260, available = 253
Findings
(1) the current ice kernel driver (ice_main.c) will pre-allocate all
required number of msix (even it's not enough for big core CPUs)
(2) the commit
https://github.com/torvalds/linux/commit/ce4626131112e1d0066a890371e14d8091323f99
has improved this logic, and it seems merged into kernel version from v6.1
So for supporting the new CPUs with more than 252 vCPUs, will Ubuntu
kernel backport above patch to the current kernel (v5.15) ?
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