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sunmoom推荐了LKML里的一个测试用例：
- #if 0
- Hi Ingo and all,
- When I was executing massive interactive processes, I found that some of them
- occupy CPU time and the others hardly run.
- It seems that some of processes which occupy CPU time always has max effective
- prio (default+5) and the others have max - 1. What happen here is...
- 1. If there are moderate number of max interactive processes, they can be
- re-inserted into active queue without falling down its priority again and
- again.
- 2. In this case, the others seldom run, and can't get max effective priority
- at next exhausting because scheduler considers them to sleep too long.
- 3. Goto 1, OOPS!
- Unfortunately I haven't been able to make the patch resolving this problem
- yet. Any idea?
- I also attach the test program which easily recreates this problem.
- Test program flow:
- 1. First process starts child proesses and wait for 5 minutes.
- 2. Each child process executes "work 8 msec and sleep 1 msec" loop
- continuously.
- 3. After 3 minits have passed, each child processes prints the # of loops
- which executed.
- What expected:
- Each child processes execute nearly equal # of loops.
- Test environment:
- - kernel: 2.6.20(*1)
- - # of CPUs: 1 or 2
- - # of child processes: 200 or 400
- - nice value: 0 or 20(*2)
- *1) I confirmed that 2.6.21-rc5 has no change regarding this problem.
- *2) If a process have nice 20, scheduler never regards it as interactive.
- Test results:
- -----------+----------------+------+------------------------------------
- # of CPUs | # of processes | nice | result
- -----------+----------------+------+------------------------------------
- | | 20 | looks good
- 1(i386) | +------+------------------------------------
- | | 0 | 4 processes occupy 98% of CPU time
- -----------+ 200 +------+------------------------------------
- | | 20 | looks good
- | +------+------------------------------------
- | | 0 | 8 processes occupy 72% of CPU time
- 2(ia64) +----------------+------+------------------------------------
- | 400 | 20 | looks good
- | +------+------------------------------------
- | | 0 | 8 processes occupy 98% of CPU time
- -----------+----------------+------+------------------------------------
- FYI. 2.6.21-rc3-mm1 (enabling RSDL scheduler) works fine in the all casees :-)
- Thanks,
- Satoru
- -------------------------------------------------------------------------------
- #endif
- /*
- * massive_intr - run @nproc interactive processes and print the number of
- * loops(*1) each process executes in @runtime secs.
- *
- * *1) "work 8 msec and sleep 1msec" loop
- *
- * Usage: massive_intr <nproc> <runtime>
- *
- * @nproc: number of processes
- * @runtime: execute time[sec]
- *
- * ex) If you want to run 300 processes for 5 mins, issue the
- * command as follows:
- *
- * $ massive_intr 300 300
- *
- * How to build:
- *
- * cc -o massive_intr massive_intr.c -lrt
- *
- *
- * Copyright (C) 2007 Satoru Takeuchi <[email]takeuchi_satoru@jp.fujitsu.com[/email]>
- *
- * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
- *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation; either version 2 of the License, or (at
- * your option) any later version.
- *
- * This program is distributed in the hope that it will be useful, but
- * WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
- * General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License along
- * with this program; if not, write to the Free Software Foundation, Inc.,
- * 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
- *
- * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
- */
- #include <sys/time.h>
- #include <sys/types.h>
- #include <sys/stat.h>
- #include <sys/mman.h>
- #include <sys/wait.h>
- #include <fcntl.h>
- #include <unistd.h>
- #include <semaphore.h>
- #include <stdio.h>
- #include <stdlib.h>
- #include <time.h>
- #include <string.h>
- #include <errno.h>
- #include <err.h>
- #define WORK_MSECS 8
- #define SLEEP_MSECS 1
- #define MAX_PROC 1024
- #define SAMPLE_COUNT 1000000000
- #define USECS_PER_SEC 1000000
- #define USECS_PER_MSEC 1000
- #define NSECS_PER_MSEC 1000000
- #define SHMEMSIZE 4096
- static const char *shmname = "/sched_interactive_shmem";
- static void *shmem;
- static sem_t *printsem;
- static int nproc;
- static int runtime;
- static int fd;
- static time_t *first;
- static pid_t pid[MAX_PROC];
- static int return_code;
- static void cleanup_resources(void)
- {
- if (sem_destroy(printsem) < 0)
- warn("sem_destroy() failed");
- if (munmap(shmem, SHMEMSIZE) < 0)
- warn("munmap() failed");
- if (close(fd) < 0)
- warn("close() failed");
- }
- static void abnormal_exit(void)
- {
- if (kill(getppid(), SIGUSR2) < 0)
- err(EXIT_FAILURE, "kill() failed");
- }
- static void sighandler(int signo)
- {
- }
- static void sighandler2(int signo)
- {
- return_code = EXIT_FAILURE;
- }
- static void loopfnc(int nloop)
- {
- int i;
- for (i = 0; i < nloop; i++)
- ;
- }
- static int loop_per_msec(void)
- {
- struct timeval tv[2];
- int before, after;
- if (gettimeofday(&tv[0], NULL) < 0)
- return -1;
- loopfnc(SAMPLE_COUNT);
- if (gettimeofday(&tv[1], NULL) < 0)
- return -1;
- before = tv[0].tv_sec*USECS_PER_SEC+tv[0].tv_usec;
- after = tv[1].tv_sec*USECS_PER_SEC+tv[1].tv_usec;
- return SAMPLE_COUNT/(after - before)*USECS_PER_MSEC;
- }
- static void *test_job(void *arg)
- {
- int l = (int)arg;
- int count = 0;
- time_t current;
- sigset_t sigset;
- struct sigaction sa;
- struct timespec ts = { 0, NSECS_PER_MSEC*SLEEP_MSECS};
- sa.sa_handler = sighandler;
- if (sigemptyset(&sa.sa_mask) < 0) {
- warn("sigemptyset() failed");
- abnormal_exit();
- }
- sa.sa_flags = 0;
- if (sigaction(SIGUSR1, &sa, NULL) < 0) {
- warn("sigaction() failed");
- abnormal_exit();
- }
- if (sigemptyset(&sigset) < 0) {
- warn("sigfillset() failed");
- abnormal_exit();
- }
- sigsuspend(&sigset);
- if (errno != EINTR) {
- warn("sigsuspend() failed");
- abnormal_exit();
- }
- /* main loop */
- do {
- loopfnc(WORK_MSECS*l);
- if (nanosleep(&ts, NULL) < 0) {
- warn("nanosleep() failed");
- abnormal_exit();
- }
- count++;
- if (time(¤t) == -1) {
- warn("time() failed");
- abnormal_exit();
- }
- } while (difftime(current, *first) < runtime);
- if (sem_wait(printsem) < 0) {
- warn("sem_wait() failed");
- abnormal_exit();
- }
- printf("%06d\t%08d\n", getpid(), count);
- if (sem_post(printsem) < 0) {
- warn("sem_post() failed");
- abnormal_exit();
- }
- exit(EXIT_SUCCESS);
- }
- static void usage(void)
- {
- fprintf(stderr,
- "Usage : massive_intr <nproc> <runtime>\n"
- "\t\tnproc : number of processes\n"
- "\t\truntime : execute time[sec]\n");
- exit(EXIT_FAILURE);
- }
- int main(int argc, char **argv)
- {
- int i, j;
- int status;
- sigset_t sigset;
- struct sigaction sa;
- int c;
- if (argc != 3)
- usage();
- nproc = strtol(argv[1], NULL, 10);
- if (errno || nproc < 1 || nproc > MAX_PROC)
- err(EXIT_FAILURE, "invalid multinum");
- runtime = strtol(argv[2], NULL, 10);
- if (errno || runtime <= 0)
- err(EXIT_FAILURE, "invalid runtime");
- sa.sa_handler = sighandler2;
- if (sigemptyset(&sa.sa_mask) < 0)
- err(EXIT_FAILURE, "sigemptyset() failed");
- sa.sa_flags = 0;
- if (sigaction(SIGUSR2, &sa, NULL) < 0)
- err(EXIT_FAILURE, "sigaction() failed");
- if (sigemptyset(&sigset) < 0)
- err(EXIT_FAILURE, "sigemptyset() failed");
- if (sigaddset(&sigset, SIGUSR1) < 0)
- err(EXIT_FAILURE, "sigaddset() failed");
- if (sigaddset(&sigset, SIGUSR2) < 0)
- err(EXIT_FAILURE, "sigaddset() failed");
- if (sigprocmask(SIG_BLOCK, &sigset, NULL) < 0)
- err(EXIT_FAILURE, "sigprocmask() failed");
- /* setup shared memory */
- if ((fd = shm_open(shmname, O_CREAT | O_RDWR, 0644)) < 0)
- err(EXIT_FAILURE, "shm_open() failed");
- if (shm_unlink(shmname) < 0) {
- warn("shm_unlink() failed");
- goto err_close;
- }
- if (ftruncate(fd, SHMEMSIZE) < 0) {
- warn("ftruncate() failed");
- goto err_close;
- }
- shmem = mmap(NULL, SHMEMSIZE, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
- if (shmem == (void *)-1) {
- warn("mmap() failed");
- goto err_unmap;
- }
- printsem = shmem;
- first = shmem + sizeof(*printsem);
-
- /* initialize semaphore */
- if ((sem_init(printsem, 1, 1)) < 0) {
- warn("sem_init() failed");
- goto err_unmap;
- }
- if ((c = loop_per_msec()) < 0) {
- fprintf(stderr, "loop_per_msec() failed\n");
- goto err_sem;
- }
- for (i = 0; i < nproc; i++) {
- pid[i] = fork();
- if (pid[i] == -1) {
- warn("fork() failed\n");
- for (j = 0; j < i; j++)
- if (kill(pid[j], SIGKILL) < 0)
- warn("kill() failed");
- goto err_sem;
- }
- if (pid[i] == 0)
- test_job((void *)c);
- }
- if (sigemptyset(&sigset) < 0) {
- warn("sigemptyset() failed");
- goto err_proc;
- }
- if (sigaddset(&sigset, SIGUSR2) < 0) {
- warn("sigaddset() failed");
- goto err_proc;
- }
- if (sigprocmask(SIG_UNBLOCK, &sigset, NULL) < 0) {
- warn("sigprocmask() failed");
- goto err_proc;
- }
- if (time(first) < 0) {
- warn("time() failed");
- goto err_proc;
- }
- if ((kill(0, SIGUSR1)) == -1) {
- warn("kill() failed");
- goto err_proc;
- }
- for (i = 0; i < nproc; i++) {
- if (wait(&status) < 0) {
- warn("wait() failed");
- goto err_proc;
- }
- }
- cleanup_resources();
- exit(return_code);
- err_proc:
- for (i = 0; i < nproc; i++)
- if (kill(pid[i], SIGKILL) < 0)
- if (errno != ESRCH)
- warn("kill() failed");
- err_sem:
- if (sem_destroy(printsem) < 0)
- warn("sem_destroy() failed");
- err_unmap:
- if (munmap(shmem, SHMEMSIZE) < 0)
- warn("munmap() failed");
- err_close:
- if (close(fd) < 0)
- warn("close() failed");
- exit(EXIT_FAILURE);
- }
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发表于 2008-03-25 16:24
发表于 2008-03-25 16:28
