Re: [RFC/SERIOUS] grilling troubled CPUs for fun and profit?

[Pavel Machek <pavel@ucw.cz>]

Hi!

>  > > Another anecdote: Upon fan failure, I once had an athlon MP *completely shatter*
>  > > (as in broke in two pieces) under extreme heat.
>  > > 
>  > > This _does_ happen.
>  > 
>  > If it happens to you... you needed a new cpu anyway. Anything non-historical
>  > *has* thermal protection.
> 
> That's the single dumbest thing I've read today.

Sorry to upset you.

> newsflash: you don't get to dictate when I (or anyone else) buys new hardware.
> Before its accident, that box happily was my home firewall for 3 years, and
> its replacement is actually an /older/ box.  I didn't "need a new cpu" at all.
> 

Yep, it is bad... broken machines die. And while proposed patches
probably will not hurt, I do not think they will help, and I do not think
anyone will ever *test* them.

>  > BTW I doubt those old athlons can be saved by cli; hlt . (Someone willing to try if old
>  > athlon can run cli; hlt code w/o heatsink?).
> 
> you snipped the important part of my mail.
> 
> "cpu_relax() and friends aren't going to save a box"
> 
> We have two completely different things being discussed in this thread.
> 
> 1. Fan failure, and the possibility to keep running.
> IMO, there's nothing we can do here, and nor should we try.

Agreed... so you  know that proposed patch would probably not prevent your old
box from self-destructing?

> 2. Situations where we forcibly lock up and spin the CPU in a tight loop,
> producing heat.  Given there are CPUs that benefit from cpu_relax()
> in such places, adding them so that they don't unnecessarily sit there
> sucking power until someone gets to the datacenter to investigate
> can only be a good thing.

Are you sure that cpu_relax actually does somenthing on pre-pentium-4 machines?

>  > And no, we probably do not want to enter C2 or C3 from doublefault handler.
> 
> I didn't see that being proposed.

Good. 
			Pavel
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