Date: Wed, 3 Feb 2010 12:20:21 +0900
From: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
To: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: "linux-mm@kvack.org" <linux-mm@kvack.org>,
       "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
       "nishimura@mxp.nes.nec.co.jp" <nishimura@mxp.nes.nec.co.jp>,
       "balbir@linux.vnet.ibm.com" <balbir@linux.vnet.ibm.com>
Subject: Re: [PATCH mmotm] memcg: use generic percpu instead of private
 implementation
Message-Id: <20100203122021.619d250f.kamezawa.hiroyu@jp.fujitsu.com>
In-Reply-To: <20100203121624.bab7be2c.kamezawa.hiroyu@jp.fujitsu.com>
References: <20100203121624.bab7be2c.kamezawa.hiroyu@jp.fujitsu.com>
Organization: FUJITSU Co. LTD.
Mime-Version: 1.0
Content-Type: text/plain; charset=US-ASCII
Content-Transfer-Encoding: 7bit
Sender: linux-kernel-owner@vger.kernel.org
Content-Length: 1979
Lines: 99

Here is a test program I used.

 1. fork() processes on each cpus.
 2. do page fault repeatedly on each process.
 3. after 60secs, kill all childredn and exit.

(3 is necessary for getting stable data, this is improvement from previous one.)

Bye.
-Kame
==

#define _GNU_SOURCE
#include <stdio.h>
#include <sched.h>
#include <sys/mman.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <signal.h>
#include <stdlib.h>

/*
 * For avoiding contention in page table lock, FAULT area is
 * sparse. If FAULT_LENGTH is too large for your cpus, decrease it.
 */
#define FAULT_LENGTH	(2 * 1024 * 1024)
#define PAGE_SIZE	4096
#define MAXNUM		(128)

void alarm_handler(int sig)
{
}

void *worker(int cpu, int ppid)
{
	void *start, *end;
	char *c;
	cpu_set_t set;
	int i;

	CPU_ZERO(&set);
	CPU_SET(cpu, &set);
	sched_setaffinity(0, sizeof(set), &set);

	start = mmap(NULL, FAULT_LENGTH, PROT_READ|PROT_WRITE,
			MAP_PRIVATE | MAP_ANONYMOUS, 0, 0);
	if (start == MAP_FAILED) {
		perror("mmap");
		exit(1);
	}
	end = start + FAULT_LENGTH;

	pause();
	//fprintf(stderr, "run%d", cpu);
	while (1) {
		for (c = (char*)start; (void *)c < end; c += PAGE_SIZE)
			*c = 0;
		madvise(start, FAULT_LENGTH, MADV_DONTNEED);
	}
	return NULL;
}

int main(int argc, char *argv[])
{
	int num, i, ret, pid, status;
	int pids[MAXNUM];

	if (argc < 2)
		return 0;

	setpgid(0, 0);
	signal(SIGALRM, alarm_handler);
	num = atoi(argv[1]);	
	pid = getpid();

	for (i = 0; i < num; ++i) {
		ret = fork();
		if (!ret) {
			worker(i, pid);
			exit(0);
		}
		pids[i] = ret;
	}
	sleep(1);
	kill(-pid, SIGALRM);
	sleep(60);
	for (i = 0; i < num; i++)
		kill(pids[i], SIGKILL);
	for (i = 0; i < num; i++)
		waitpid(pids[i], &status, 0);
	return 0;
}

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/