Re: Attempted summary of "RT patch acceptance" thread, take 2

[Daniel Walker]

On Mon, 2005-07-11 at 10:19 -0700, Paul E. McKenney wrote:

> OK, interesting point, though this would apply only to interrupt latency,
> not to scheduling latency or to latency for any other system services,
> right?

Only for interrupt latency, that I know of. 

> Do you believe that the 50-us delay measured by Kristian and Karim was
> due to APM or due to hardware (as Karim suspected)?  If the latter,
> any guesses as to the cause of the holdup?  50 us is a -really- long
> time for ~100 instructions on today's hardware, even if each instruction
> misses the cache!

There are ~100 interrupt off critical sections. Those sections can be
variable numbers of instructions. I would imagine that whatever maximum
latency that Kristian and Karim found is the maximum for their hardware.

Daniel

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