Phased updater and weekends

[Adrien Nader]

On Thu, Jan 09, 2025, Julian Andres Klode wrote:
> After some quick chat, I'd like to propose that we extend the
> policy to not release SRUs from Fri-Sun to the phased updates
> and not phase them to a 100% at those times.
> 
> Cautious users configure their systems to not install phased updates,
> so they will only see new updates once they reach 100% and that
> happening on weekends is not particularly helpful.
> 
> I propose that essentially when the phased-updater is started
> between
> 
>     Friday 00:00 UTC and Monday 12:00 UTC
> 
> that it never increments the value to 100.
> 
> The second aspect of the weekend question is whether to increment
> the phased update percentage at all, that is should people using
> the defaults be exposed to new updates over the weekend?
> 
> To recall, a phased update is usually installed if
> 
> Phased-Update-Percentage > rng(seeded with:
>                                 name-version-machineId).randint(0,100)
> 
> 
> When increasing from 10% to 20%, that means 10% more users will
> receive the update such that a total of 20% of machines received
> it.
> 
> Or default policies are:
> 
> - low: 10 points per run (2.5 days to complete)
> - medium: 5 points per run (5 days to complete)
> - slow: 1 point per run (25 days to complete)
> 
> These likely would need adjusting, as we run the phased
> updater only for 3.5 instead of 7 days. Particularly, the
> slow policy would now take 7 weeks instead of 3.5 (25/7=3.5),
> which is too slow, accordingly slow should receive a bump
> to receive 2 points per run.
> 
> Medium may be worthwhile to increase it a bit, such that it
> takes 4 days to complete, this avoids it skipping over 2
> weekends (the last released update should be half a day in
> the current week + 3.5 days the next week = 4 days).
> 
> It may make sense to add an adjustment factor for a weekend
> to scale non-linearly after to "catch up". If the update was
> phased at 50% over the weekend, that's very different from
> an update that was phased at 10% over the weekend and it
> could move to 100% faster.

Medium is a level I asked for specifically for openssl. It's pretty
recent and its speed was scientifically chosen as between low and slow,
and that's it. Feel free to change it (although it's possible that some
other packages use the same level).

As for the topic as a whole, not updating on week-ends may delay updates
for non-entreprise users who may be more active during week-ends and
that may be a loss. You could also frame that as "not disturbing
people's week-ends" however.

-- 
Adrien