Re: [pve-devel] applied: [PATCH manager] ui: RRD graphs: display PSI as percent

[Friedrich Weber <f.weber@proxmox.com>]

On 31/07/2025 16:00, Thomas Lamprecht wrote:
> On Thu, 31 Jul 2025 15:51:42 +0200, Friedrich Weber wrote:
>> Pressure stall information are actually in percent. This is not
>> mentioned explicitly in the documentation, but e.g. in the kernel
>> source [1]:
>>
>>> The percentage of wall clock time spent in those compound stall
>>> states gives pressure numbers between 0 and 100 for each resource,
>>> where the SOME percentage indicates workload slowdowns and the FULL
>>> percentage indicates reduced CPU utilization:
>>>
>>> 	%SOME = time(SOME) / period
>>> 	%FULL = time(FULL) / period
>>
>> [...]
> 
> This was a bit strange for me, I seemingly ingrained some wrong knownledge when
> getting first exposed to PSI when that was a new thing back in 2019 or so,
> either the docs where worded a bit differently or I just read a bit to much
> into the wording (more likely), anyhow thanks for clarifying this, one thing
> that I'm still wondering is this then percent for real (i.e. * 100 already) or
> a ratio? Or would we need to do *= 100 scaling?

I think it's fine now -- at least for /proc/pressure/*, the range is
0..100, e.g. when running a fio in parallel:

# cat /proc/pressure/io
some avg10=39.42 avg60=21.00 avg300=5.98 total=49530229
full avg10=39.41 avg60=20.94 avg300=5.96 total=48766096

And this is also correctly displayed in the GUI now.

> 
> Anyway, as this restores the status quo with rationale it's already an
> improvement as is, so: Applied, thanks!

Thanks!

> 
> [1/1] ui: RRD graphs: display PSI as percent
>       commit: 2753e104a1e6effa4a0ae995f13636a02f3557af



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