Re: [Discuss][i386] Platform SMIs and their interferance with tscbased delay calibration

[Linus Torvalds]

On Fri, 28 Jan 2005, Venkatesh Pallipadi wrote:
>
> Current tsc based delay_calibration can result in significant errors in
> loops_per_jiffy count when the platform events like SMIs (System
> Management Interrupts that are non-maskable) are present. This could
> lead to potential kernel panic(). This issue is becoming more visible
> with 2.6 kernel (as default HZ is 1000) and on platforms with higher SMI
> handling latencies. During the boot time, SMIs are mostly used by BIOS
> (for things like legacy keyboard emulation).

Hmm. I see the problem, but I don't know that I'm 100% happy with this
patch, though.

In particular, I don't see why you didn't just put this in the generic 
calibrate_delay() routine. You seem to have basically duplicated it, and 
added the "guess from an external timer" code - and I don't see what's 
non-generic about that, except for some trivial "what's the current timer" 
lookup.

		Linus
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