System details:
Freescale [EMAIL PROTECTED]
Kernel 2.6.18
Problem:
When we log debug output via the serial console on a multithreaded
application, the console throughput may get clogged and then we
experience a >300ms deadlock.
Quick and dirty test program: threadtest.c:
//----------------------------------------------------------------------
-------------------------
#include <pthread.h>
#include <stdio.h>
#include <sys/time.h>
#define THREAD_DELAY 1000
void* thread_1(void* unused)
{
while (1)
{
usleep(THREAD_DELAY);
fprintf(stdout," <----- thread 1\n");
}
return NULL;
}
void* thread_2(void* unused)
{
static long ts_old;
long ts;
struct timeval tv;
while (1)
{
usleep(THREAD_DELAY);
fprintf(stdout," <----- thread 2\n");
gettimeofday (&tv, NULL);
ts = (tv.tv_sec * 1000L) + (tv.tv_usec / 1000L);
if ((ts - ts_old) > 100)
{
fprintf(stdout, "!!!!!!!!!!! thread2 interval
timeout = %d ms\n",(int)(ts - ts_old));
}
ts_old = ts;
}
return NULL;
}
int main()
{
pthread_t pthread_id_1, pthread_id_2;
pthread_create(&pthread_id_1,NULL,&thread_1,NULL);
pthread_create(&pthread_id_2,NULL,&thread_2,NULL);
while (1)
{
}
return 0;
}
//----------------------------------------------------------------------
-------------------------
Build command on our platform:
powerpc-linux-uclibc-gcc threadtest.c -lpthread -o threadtest
Execute: ./threadtest > /dev/console &
Uboot settings for the serial console:
consoledev=ttyS0
baudrate=115200
stdin=serial
stdout=serial
stderr=serial
boot_go=setenv bootargs console=$consoledev,$baudrate $args_rtc
$args_mtd $args_nfs $args_debug;bootm $addr_kernel $addr_root $addr_dtb
Expected output [snippet] on the console:
.... /\ ........
<----- thread 1
<----- thread 2
<----- thread 1
<----- thread 2
<----- thread 1
<----- thread 2
<----- thread 1
<----- thread 2
<----- thread 1
<----- thread 2
<----- thread 1
.... /\ ........
Real output on the console:
.... /\ ........
<----- thread 1
<----- thread 2
<----- thread 1
<----- thread 2
<----- thread 1
<----- thread 2
!!!!!!!!!!! thread2 interval timeout = 335 ms
<----- thread 1
<----- thread 2
<----- thread 1
<----- thread 2
<----- thread 1
.... /\ ........
This timeout shows up around every second and has always about the same
value of 335 ms.
Can somebody reproduce this behaviour ( the console speed and/or thread
interval may have to be tweaked to clog the serial output) ?
Thank you in advance for your help.
Bernard
-----------------------------------------------------------
Bernard Willaert
Software Development Engineer Modality OEM Solutions
BARCO Medical Imaging Division
President Kennedypark 35 - B-8500 KORTRIJK - BELGIUM
Tel. +32 56 233 439 Fax +32 56 233 457
www.barco.com/medical
mailto:[EMAIL PROTECTED]
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