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RE: how to get thread priorities to work
- From: "Lubashev, Igor" <ilubashe at akamai dot com>
- To: "Burkhardt, Glenn" <Glenn dot Burkhardt at goodrich dot com>, "pthreads-win32 at sourceware dot org" <pthreads-win32 at sourceware dot org>
- Date: Mon, 2 May 2011 17:51:28 -0400
- Subject: RE: how to get thread priorities to work
- References: <F69D5B35CAB1F043B9EE359EDA4318DC08B07869@nhc0ex17.goodrich.root.local>
Without looking too much into this, are you trying this on a multi-core machine (either multiple cores or one hyperthreading core)?
- Igor
-----Original Message-----
From: pthreads-win32-owner@sourceware.org [mailto:pthreads-win32-owner@sourceware.org] On Behalf Of Burkhardt, Glenn
Sent: Monday, May 02, 2011 5:43 PM
To: pthreads-win32@sourceware.org
Subject: how to get thread priorities to work
I've been puzzling over this for way too long now. I can't seem to get
thread priorities to work. Any help will be appreciated.
For the code that follows, I would expect that only one of the threads
would run, and the counter for the lower priority thread would never
increment. But that's not the case, on both a WinXP and Win7 system
(built with MinGW 10/30/2010, gcc 4.5.2). The counter values for the
two threads are close to being the same (e.g., 94686137, 99999999).
TIA...
#include <math.h>
#include <windows.h>
#include <stdio.h>
#include <pthread.h>
#include <errno.h>
void sleep10(int *cnt) {
double x;
for (int i=0; i < 100000000; i++) {
x = sin(1.0/(1.0+i));
*cnt = i;
}
}
void printError() {
char *msg;
int errorCode = GetLastError();
FormatMessage(FORMAT_MESSAGE_ALLOCATE_BUFFER
| FORMAT_MESSAGE_FROM_SYSTEM
| FORMAT_MESSAGE_IGNORE_INSERTS,
0, errorCode, 0, (LPTSTR)&msg, 0, 0);
printf("error=%d: %s\n", errorCode, msg);
LocalFree(msg);
}
void *thread(void *count) {
printf("%p: %d\n", count, GetThreadPriority(GetCurrentThread()));
sleep10(count);
printf("%p exit\n", count);
return 0;
}
int main() {
struct sched_param spMax, spMin;
pthread_attr_t attrMax, attrMin;
pthread_t tMax, tMin;
int minCount, maxCount;
spMax.sched_priority = sched_get_priority_max(SCHED_OTHER);
spMin.sched_priority = sched_get_priority_min(SCHED_OTHER);
pthread_attr_init(&attrMax);
pthread_attr_setschedparam(&attrMax, &spMax);
pthread_attr_init(&attrMin);
pthread_attr_setschedparam(&attrMin, &spMin);
pthread_create(&tMax, &attrMax, thread, &maxCount);
pthread_create(&tMin, &attrMin, thread, &minCount);
printf("join %d\n", GetThreadPriority(GetCurrentThread()));
pthread_join(tMax, 0);
printf("%p: %d, %p: %d\n", &minCount, minCount, &maxCount,
maxCount);
return 0;
}