Thomas,
More info below, I hope it helps.
Iratxo Pichel Ortiz wrote:
Thomas,
Iratxo Pichel Ortiz wrote:
2.6.29-rt16, right ?
I have also tried rt18, but as I had thought seeing change-logs, the
behavior is exactly the same.
You were right here :) It was 29.
Do you know what could be causing this issue. I have managed to
repeat this
traces (NOHZ...) without using my code, using a workqueue and in the
work
just by doing something like:
work_func() {
mdelay(10);
msleep(10);
queue_work(myqueue, mywork);
}
And then by heavy loading the box from the outside.
I have written a very small module that causes the
"local_softirq_pending" under not some load. Please find code at the end
of this email. Here is pasted some traces of dmesg (I have increased the
ratelimit of the "NOHZ: local..." trace to 250.
The only strange thing here is that I am calling "set_workqueue_prio" (I
have hacked source to export this symbol), and I am starting to think
that this could not be a good idea. Any hints about this?
[ 648.954000] NOHZ: local_softirq_pending
0e
[ 648.955000] NOHZ: local_softirq_pending
0e
[ 648.956000] NOHZ: local_softirq_pending
0e
I have changed the implementation of the module test to use kthreads
instead of workqueues. The behavior is exactly the same. I have tried
with prios from 1 to 99. Please find the code below as before. I have
also atached the differente softirqs codes that had been pending in some
of the tests.
Does it work when you disable CONFIG_NOHZ ?
Still pending to test.
I will try this and let the list know.
Thanks,
tglx
Thanks a lot again!
Iratxo.
---- DMESG ----
[4294833.294000] NOHZ: local_softirq_pending
06
[4294833.295000] NOHZ: local_softirq_pending
06
[4294834.246000] NOHZ: local_softirq_pending
02
[4294834.247000] NOHZ: local_softirq_pending
02
[4294834.248000] NOHZ: local_softirq_pending 02
---- Test module code ----
#include <linux/module.h>
#include <linux/kthread.h>
#include <linux/sched.h>
#include <linux/delay.h>
#define LATENCY_PRIO 1
struct task_struct *t;
int LatencyzerWork(void* data)
{
static int count;
while(1) {
/* Busy and normal waiting */
mdelay(10);
msleep(1);
/* Requeue work */
if(count++ > 400000)
break;
}
printk("LAT: Count reached %d, stopped latencying\n", count);
return 0;
}
int __init LatencyzerInit(void)
{
struct sched_param schedp;
/* Prepare Thread */
printk("LAT: Initializing latencyzer\n");
if(!(t = kthread_create(LatencyzerWork, NULL, "LATENCY"))) {
printk("LAT: Error creating thread\n");
return -1;
}
/* Change task prio */
schedp.sched_priority = LATENCY_PRIO;
sched_setscheduler(t, SCHED_FIFO, &schedp);
printk("LAT: Task prio set to %u\n", LATENCY_PRIO);
/* Run thread */
wake_up_process(t);
return 0;
}
void __exit LatencyzerExit(void)
{
printk("LAT: Latencyzer exiting...");
/* Done here */
kthread_stop(t);
printk(" DONE\n");
return;
}
module_init(LatencyzerInit);
module_exit(LatencyzerExit);
MODULE_LICENSE("GPL");
--
Iratxo Pichel Ortiz
Software Development Manager
Albentia Systems S.A.
http://www.albentia.com
Tel: +34 914400567
Cel: +34 663808405
Fax: +34 914400569
C\Margarita Salas 22
Parque Tecnológico de Leganés
Leganés (28918)
Madrid
Spain
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