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SubjectRe: [patch] Real-Time Preemption, -RT-2.6.12-V0.7.49-00


Esben Nielsen
Work:
Cotas Computer Technology A/S
Paludan Mullersvej 82
8200 Aarhus N
Private
Moellegade 7A, 3., 4
8000 Aarhus C
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+45 86 12 73 79
Mobile:
+45 27 13 10 05


On Tue, 21 Jun 2005, Ingo Molnar wrote:

>
> * Esben Nielsen <simlo@phys.au.dk> wrote:
>
> > I am seeing very high latencies on 2.6.12-RT-V0.7.50-04 with a
> > modified realfeel2: maximum is 246 us. Shouldn't it be in the order of
> > 50 us?
>
> i never got reliable results from realfeel - it should do the kind of
> careful things rtc_wakeup does to avoid false positives.
>
I tried with rtc_wakeup while I was at work (which is on my disk at home)
- but it crashed my machine (one have to be _very_ carefull about what you
do when you run in a task with RT priority!). I have fixed it now (see
below patch) and it is running for the night. Let us see if I get similar
results.

Esben

diff -Naur wakeup.cc~ wakeup.cc
--- wakeup.cc~ 2004-12-10 13:41:59.000000000 +0100
+++ wakeup.cc 2005-06-21 22:28:53.000000000 +0200
@@ -359,8 +359,7 @@
cycles_t last_cycles_count;
double max_jitter = 0;

- struct timespec pause;
- pause.tv_nsec = 10000;
+ struct timespec pause = { 0, 10000};

std::cout.flags(std::ios::fixed);
std::cout << std::setprecision(1);
@@ -428,7 +427,11 @@
if (max_number_of_irqs > 0 && total_num_of_irqs >= max_number_of_irqs)
stopit = true;
}
- nanosleep(&pause,0);
+ if(nanosleep(&pause,0))
+ {
+ perror("nanosleep:");
+ exit(1);
+ }
}
std::cout << "done." << std::endl;
std::cout << "total # of irqs: " << total_num_of_irqs << std::endl;

-
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