lkml.org 
[lkml]   [2005]   [Jul]   [13]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: Attempted summary of "RT patch acceptance" thread, take 2
On Mon, Jul 11, 2005 at 10:25:28AM -0700, Daniel Walker wrote:
> 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.

Does your ~100-instruction estimate include scheduler_tick() interrupt?
From another thread, I gather that it runs with hardware interrupts
disabled.

Thanx, Paul
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/

\
 
 \ /
  Last update: 2005-07-13 16:32    [W:0.040 / U:0.316 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site