T6917: fix RPS ethernet settings for CPUs with more than 32 cores

[sever-sever]

Change Summary

The maximum value that could be written for the 'rpc_cpu' is 4294967295 or 0xffffffff
Ensure that the bitmask size doesn't exceed 32 bits, even if the system has more CPUs.

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Code style update (formatting, renaming)
• Refactoring (no functional changes)
• Migration from an old Vyatta component to vyos-1x, please link to related PR inside obsoleted component
• Other (please describe):

Related Task(s)

• https://vyos.dev/T6917

Related PR(s)

Component(s) name

ethernet, rps

Proposed changes

How to test

The system with 96 CPUs

vyos@r-wan# lscpu
Architecture:             x86_64
  CPU op-mode(s):         32-bit, 64-bit
  Address sizes:          40 bits physical, 48 bits virtual
  Byte Order:             Little Endian
CPU(s):                   96
  On-line CPU(s) list:    0-95

Try to configure offload RPS

# set interfaces ethernet eth1 offload rps
[edit]
# commit
[ interfaces ethernet eth1 ]
VyOS had an issue completing a command.

OSError: [Errno 75] Value too large for defined data type

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/usr/libexec/vyos/conf_mode/interfaces_ethernet.py", line 433, in <module>
    apply(c)
  File "/usr/libexec/vyos/conf_mode/interfaces_ethernet.py", line 410, in apply
    e.update(ethernet)
  File "/usr/lib/python3/dist-packages/vyos/ifconfig/ethernet.py", line 430, in update
    self.set_rps(dict_search('offload.rps', config) != None)
  File "/usr/lib/python3/dist-packages/vyos/ifconfig/ethernet.py", line 328, in set_rps
    self._write_sysfs(f'/sys/class/net/{self.ifname}/queues/rx-{i}/rps_cpus', f'{rps_cpus:x}')
  File "/usr/lib/python3/dist-packages/vyos/ifconfig/control.py", line 130, in _write_sysfs
    write_file(filename, str(value))
  File "/usr/lib/python3/dist-packages/vyos/utils/file.py", line 69, in write_file
    raise e
  File "/usr/lib/python3/dist-packages/vyos/utils/file.py", line 61, in write_file
    with open(fname, 'w' if not append else 'a') as f:
OSError: [Errno 75] Value too large for defined data type

noteworthy:
cmd 'ethtool --features eth1 lro on'
returned (out):

returned (err):
Could not change any device features

[[interfaces ethernet eth1]] failed
Commit failed

Try to configure 33 CPUs and get the error Value too large for defined data type

>>> hex((1 << 33) -1)
'0x1ffffffff'
>>> 

root@r-wan:/home/vyos# echo 1ffffffff > /sys/class/net/eth0/queues/rx-0/rps_cpus
bash: echo: write error: Value too large for defined data type
root@r-wan:/home/vyos# 

Try 32 CPUs (for the chunk):

>>> hex((1 << 32) -1)
'0xffffffff'
>>> 
>>> (1 << 32) -1
4294967295
>>> 

root@r-wan:/home/vyos# echo ffffffff > /sys/class/net/eth0/queues/rx-0/rps_cpus
root@r-wan:/home/vyos# 
root@r-wan:/home/vyos# cat /sys/class/net/eth0/queues/rx-0/rps_cpus
00000000,00000000,ffffffff
root@r-wan:/home/vyos# 

After the fix:

vyos@r-wan# set interfaces ethernet eth0 offload rps 
[edit]
vyos@r-wan# commit
[edit]
vyos@r-wan# 
[edit]
vyos@r-wan# cat /sys/class/net/eth0/queues/rx-0/rps_cpus 
fffffffe,ffffffff,ffffffff
[edit]
vyos@r-wan# 

Smoketest result

Checklist:

• I have read the CONTRIBUTING document
• I have linked this PR to one or more Phabricator Task(s)
• I have run the components SMOKETESTS if applicable
• My commit headlines contain a valid Task id
• My change requires a change to the documentation
• I have updated the documentation accordingly

[github-actions]

👍
No issues in PR Title / Commit Title

[c-po]

What happens on:

echo 00000000,00000001,ffffffff > /sys/class/net/eth0/queues/rx-0/rps_cpus

[sever-sever]

What happens on:

echo 00000000,00000001,ffffffff > /sys/class/net/eth0/queues/rx-0/rps_cpus

Interesting thing

root@r-wan:/home/vyos# echo 00000000,00000001,ffffffff > /sys/class/net/eth0/queues/rx-0/rps_cpus
root@r-wan:/home/vyos# 
root@r-wan:/home/vyos# cat /sys/class/net/eth0/queues/rx-0/rps_cpus
00000000,00000001,ffffffff
root@r-wan:/home/vyos# 

[sever-sever]

@c-po I updated PR and logic

vyos@r-wan# cat /sys/class/net/eth0/queues/rx-0/rps_cpus 
00000000,00000000,00000000
[edit]
vyos@r-wan# 
[edit]
vyos@r-wan# set interfaces ethernet eth0 offload rps 
[edit]
vyos@r-wan# commit
[edit]
vyos@r-wan# 
[edit]
vyos@r-wan# 
[edit]
vyos@r-wan# cat /sys/class/net/eth0/queues/rx-0/rps_cpus 
fffffffe,ffffffff,ffffffff
[edit]
vyos@r-wan# 

[github-actions]

CI integration ❌ failed!

Details

CI logs

• CLI Smoketests (no interfaces) ❌ failed
• CLI Smoketests (interfaces only) ❌ failed
• Config tests ❌ failed
• RAID1 tests ❌ failed
• TPM tests ❌ failed

[dmbaturin]

os.cpu_count() still returns numbers un-adjusted for SMT like Intel Hyper-Threading. We have a function that returns physical CPUs only in (vyos.utils.cpu).

I'm not completely sure if the distinction can be truly important here, but maybe use that.

[sever-sever]

As we do not know which cores are real cores it is useless
In this case we interested in total cores and calculate a bit mask for CPU’s
And it is not new, we used this before

this way it could be the worse thing if you have 4 CPU and 2 threads
For example real cores could be 0,2,4,6 and logical cores 1,3,5,7. What will be if you calculate only 4 cores (which is mix in this case of real/logical cores)?
In this case it will process by 2 real and 2 logical cores instead of all cores.