UHD 630 # mesa-intel: warning: Performance support disabled, consider sysctl dev.i915.perf_stream_paranoid=0

https://forum.manjaro.org/t/cant-change-dev-i915-perf-stream-paranoid-to-0/66339/9

That says "Yes ‘consider’ is a typo" [someone wrote 'sudo consider sysctl ...']

I know that "consider" is for the human operator, not a shell command.
That's why I asked,
 Q2: What advantages and disadvantages should *I* consider?

I did try to extract more information from that page, there seems to be some troubleshooting using
systemctl status systemd-sysctl.service
however on my system the output is brief:

# systemctl status systemd-sysctl.service
● systemd-sysctl.service - Apply Kernel Variables
     Loaded: loaded (/lib/systemd/system/systemd-sysctl.service; static)
     Active: active (exited) since Sun 2022-04-17 21:28:23 HKT; 1 day 1h ago
       Docs: man:systemd-sysctl.service(8)
             man:sysctl.d(5)
   Main PID: 502 (code=exited, status=0/SUCCESS)
        CPU: 2ms

Apr 17 21:28:23 localhost systemd[1]: Finished Apply Kernel Variables.

I also tried the following and obtained merely:
# journalctl -xefu systemd-sysctl.service
Apr 17 21:28:23 localhost systemd[1]: Finished Apply Kernel Variables.
░░ Subject: A start job for unit systemd-sysctl.service has finished successfully
░░ Defined-By: systemd
░░ Support: http://www.ubuntu.com/support
░░
░░ A start job for unit systemd-sysctl.service has finished successfully.
░░
░░ The job identifier is ...

In particular, in the recommended link, someone asked, without receiving a reply,

"That’s great, but what does consider sysctl dev.i915.perf_stream_paranoid=0 actually mean and do? Can someone shed any light on this?"

and the final comment addresses something that worked for a particular Manjaro system which seems to do things differently than Ubuntu (there is no /etc/mkinitcpio.conf, etc)

This seems to be relevant; I will try it out:

https://www.intel.com/content/www/us/en/developer/articles/technical/enabling-vulkan-vk-intel-performance-query-extension-in-ubuntu.html

On boot, the i915 kernal module enables the paranoid performance collection mode by default. To use the VK_INTEL_performance_query extension, this paranoid mode must be disabled.

    A manual approach to do this is to perform the following command:

    sudo sysctl -w dev.i915.perf_stream_paranoid=0

    An automated approach to do this is to add a cron job that executes whenever the platform reboots, as follows:

    sudo crontab -e # Add the following line at the end or as the 1st no comment line:
    @reboot /sbin/sysctl -w dev.i915.perf_stream_paranoid=0

    After manually performing 7.1 or doing 7.2 and a later reboot, the "0" perf_stream_paranoid mode change can be confirmed by using the following command:

    sysctl -n dev.i915.perf_stream_paranoid

https://www.intel.com/content/www/us/en/developer/articles/technical/enabling-vulkan-vk-intel-performance-query-extension-in-ubuntu.html

sudo sysctl -w dev.i915.perf_stream_paranoid=0

does make the message go away (for current boot).
I've added it to crontab as shown above, will report if it does not work for future boots.

Q: Are there any problems this might cause, that users should be on the lookout for?

I thought the link explained how to add the text. Thanks Philip for explaining a little more.

Just look out for weird system behaviour or performance issues. Should be OK though. I suggest you add the link to your favourites or make a script to populate the files if you need to reinstall again

Conclusion: See post #4. The intel link is informative and the recommendation works after reboot.

Thank you @andrew-woodhead666 for your comments and suggestions!

I would suggest that you edit /etc/sysctl.conf or /etc/sysctl.d/99-sysctl.conf (the latter is a symlink to the former in my case) rather than adding it to crontab.

The line should read:
dev.i915.perf_stream_paranoid=0