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* [BUG] perf: hard lockup when using perf-sched
@ 2010-03-17  7:21 Li Zefan
  2010-03-24  5:52 ` Li Zefan
  0 siblings, 1 reply; 16+ messages in thread
From: Li Zefan @ 2010-03-17  7:21 UTC (permalink / raw)
  To: Ingo Molnar, Peter Zijlstra
  Cc: Frederic Weisbecker, Arnaldo Carvalho de Melo, Paul Mackerras,
	LKML

[-- Attachment #1: Type: text/plain, Size: 374 bytes --]

An idea came to me that running perf-sched with a fork "bomb" might
reveal some bug.

So I wrote a program (attached), and did the following test:

# gcc fork.c
# ./a.out &
# perf sched record

After a few seconds, the machine froze, without printing any message.

I've tried the test both on v2.6.34-rc1 and v2.6.34-rc1-tip+.

I'll send you any other information you need.

[-- Attachment #2: fork.c --]
[-- Type: text/plain, Size: 404 bytes --]

#include <unistd.h>
#include <stdlib.h>
#include <stdio.h>
#include <sys/types.h>
#include <sys/wait.h>

int main(void)
{
	int i;
	int pid;

	while (1) {
		for (i = 0; i < 400; i++) {
			pid = fork();
			if (pid == 0) {
				return 0;
			} else if (pid < 0) {
				fprintf(stderr, "faild to fork!\n");
				continue;
			}
		}

		for (i = 0; i < 400; i++)
			if (wait(NULL) < 0)
				break;
	}

	return 0;
}


^ permalink raw reply	[flat|nested] 16+ messages in thread

end of thread, other threads:[~2010-04-02 19:08 UTC | newest]

Thread overview: 16+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2010-03-17  7:21 [BUG] perf: hard lockup when using perf-sched Li Zefan
2010-03-24  5:52 ` Li Zefan
2010-03-24  7:32   ` Mike Galbraith
2010-03-24  8:17     ` Mike Galbraith
2010-03-25  8:04       ` Li Zefan
2010-03-25  9:27         ` Mike Galbraith
2010-03-25  9:54           ` Peter Zijlstra
2010-03-26 10:11           ` Mike Galbraith
2010-03-26 17:23             ` Frederic Weisbecker
2010-03-26 19:10               ` Mike Galbraith
2010-03-26 19:27                 ` Frederic Weisbecker
2010-03-26 20:22                   ` Mike Galbraith
2010-03-26 21:41                     ` Frederic Weisbecker
2010-03-26 21:45                     ` Frederic Weisbecker
2010-03-29  2:01             ` Li Zefan
2010-04-02 19:07             ` [tip:perf/core] perf: Fix 'perf sched record' deadlock tip-bot for Mike Galbraith

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