From mboxrd@z Thu Jan  1 00:00:00 1970
From: Evgeniy Polyakov <johnpol@2ka.mipt.ru>
Subject: Re: [PATCH 2.6.11-rc4-mm1] connector: Add a fork connector
Date: Thu, 03 Mar 2005 14:51:29 +0300
Message-ID: <1109850689.28266.144.camel@uganda>
References: <1109240677.1738.196.camel@frecb000711.frec.bull.fr>
	 <1109753292.8422.117.camel@frecb000711.frec.bull.fr>
	 <42268201.80706@ak.jp.nec.com>  <20050303084656.A15197@2ka.mipt.ru>
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Cc: Guillaume Thouvenin <guillaume.thouvenin@bull.net>,
        Andrew Morton <akpm@osdl.org>, lkml <linux-kernel@vger.kernel.org>,
        elsa-devel <elsa-devel@lists.sourceforge.net>,
        Jay Lan <jlan@engr.sgi.com>, Gerrit Huizenga <gh@us.ibm.com>,
        Erich Focht <efocht@hpce.nec.com>, Netlink List <netdev@oss.sgi.com>
To: Kaigai Kohei <kaigai@ak.jp.nec.com>
In-Reply-To: <20050303084656.A15197@2ka.mipt.ru>
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Simple program to test fork() performance.
#include <sys/signal.h>
#include <sys/time.h>

int main(int argc, char *argv[])
{
        int pid;
        int i =3D 0, max =3D 100000;
        struct timeval tv0, tv1;
        struct timezone tz;
        long diff;

        if (argc >=3D 2)
                max =3D atoi(argv[1]);

        signal(SIGCHLD, SIG_IGN);

        gettimeofday(&tv0, &tz);
        while (i++ < max) {
                pid =3D fork();
                if (pid =3D=3D 0) {
                        sleep(1);
                        exit (0);
                }
        }
        gettimeofday(&tv1, &tz);

        diff =3D (tv1.tv_sec - tv0.tv_sec)*1000000 + (tv1.tv_usec - tv0.tv_=
usec);

        printf("Average per process fork+exit time is %ld usecs [diff=3D%lu=
, max=3D%d].\n", diff/max, diff, max);
        return 0;
}

Creating 10k forks 100 times.
Results on 2-way SMP(1+1HT) Xeon for one fork()+exit():

2.6.11-rc4-mm1                                   494 usec
2.6.11-rc4-mm1-fork-connector-no_userspace       509 usec
2.6.11-rc4-mm1-fork-connector-userspace          520 usec

5% fork() degradation(connector with userspace vs. vanilla) with fork() con=
nector.
On my test system global fork lock does not cost anything
(tested both with and without userspace listener), but it is only 2-way(pse=
udo).

--=20
        Evgeniy Polyakov

Crash is better than data corruption -- Arthur Grabowski

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