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

["Shannon Sterz" <s.sterz@proxmox.com>]

On Thu Jul 31, 2025 at 3:56 PM CEST, 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?
>
> Anyway, as this restores the status quo with rationale it's already an
> improvement as is, so: Applied, thanks!

if i remember correctly and read the kernel documentation correctly,
this is proper percent (%) [1]. so no additional multiplying necessary.

> The ratios (in %) are tracked as recent trends over ten, sixty, and
> three hundred second windows, which gives insight into short term
> events as well as medium and long term trends.

also did i quick check here on my machine (by compiling pbs):

> ==> /proc/pressure/cpu <==
> some avg10=10.63 avg60=3.66 avg300=0.87 total=54165853

so the `avg10=10.63` should be percent.

[1]: https://www.kernel.org/doc/html/latest/accounting/psi.html

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