Re: [PATCH] nvme: lower default APST max latency to 25ms

[Ferran Duarri <ferran.duarri@me.com>]

Alexey - thanks, that's a real point I hadn't considered: if EXLAT is
deliberately inflated to keep Windows on ps3, the 100ms default isn't a bug,
it's aligned with what vendors actually tuned for.

The measurement itself I think still holds - it's reading what the drive's
live APST table targets, not just trusting the label, and the wake cost at
ps4 was real regardless of why 43ms is the number on the tin. But that's a
different question from whether Linux should default away from it.

What's the OEM precedent you mentioned - did lowering the bound before break
something specific, or was it more general pushback? Trying to understand if
this needs to stay a boot-time opt-in (which it already is via
default_ps_max_latency_us) rather than ever being a compiled default, on any
hardware.

Also - sorry for the fourth copy of this patch landing in your inbox on the
28th. That was a bookkeeping failure on my end, not a deliberate re-post; it
went out after your reply had already arrived and should not have.

Cheers,
Ferran