“帮助进程 XYZ 不迁移。” Moshe Bar 在下面解释了为什么有些进程会迁移，而有些进程不会迁移。但在那之前，您可以查看 /proc/$pid/，那里通常有一个 cantmove 文件，它会告诉您为什么某个进程无法迁移。
进程也可能被锁定。您可以使用以下命令检查进程是否被锁定：
cat /proc/$PID/lock |
现在听听 Moshe 本人对此话题的看法。
通常人们拥有相同的内核，但在不同的发行版上，例如 RedHat 和 Debian 的混合环境，来自不同发行版的 rc 脚本倾向于以不同的方式启动 openmosix。某些实现完全修改 /etc/inittab 以使用以下方式启动所有守护进程（及其子进程）：
mosrun -h |
好的，如果启动次数多于本地 CPU 数量，则这个简单的程序应该始终迁移。因此，对于双路 SMP 系统，如果集群中的其他节点至少具有与本地节点相同的速度，则启动此程序 3 次将开始迁移
int main() {
unsigned int i;
while (1) {
i++;
}
return 0;
} |
像这样的示例程序永远不会迁移
#include <sys/types.h>
#include <sys/ipc.h>
#include <sys/shm.h>
...
key_t key; /* key to be passed to shmget() */
int shmflg; /* shmflg to be passed to shmget() */
int shmid; /* return value from shmget() */
int size; /* size to be passed to shmget() */
...
key = ...
size = ...
shmflg) = ...
if ((shmid = shmget (key, size, shmflg)) == -1) {
perror("shmget: shmget failed"); exit(1); } else {
(void) fprintf(stderr, "shmget: shmget returned %d\n", shmid);
exit(0);
}
... |
使用管道的程序可以很好地迁移
int pdes[2];
pipe(pdes);
if ( fork() == 0 )
{ /* child */
close(pdes[1]); /* not required */
read( pdes[0]); /* read from parent */
.....
}
else
{ close(pdes[0]); /* not required */
write( pdes[1]); /* write to child */
.....
} |
//
// Very simple program demonstrating the use of threads.
//
// Command-line argument is P (number of threads).
//
// Each thread writes "hello" message to standard output, with
// no attempt to synchronize. Output will likely be garbled.
//
#include <iostream>
#include <cstdlib> // has exit(), etc.
#include <unistd.h> // has usleep()
#include <pthread.h> // has pthread_ routines
// declaration for function to be executed by each thread
void * printHello(void * threadArg);
// ---- Main program -------------------------------------------------
int main(int argc, char* argv[]) {
if (argc < 2) {
cerr << "Usage: " << argv[0] << " numThreads\n";
exit(EXIT_FAILURE);
}
int P = atoi(argv[1]);
// Set up IDs for threads (need a separate variable for each
// since they're shared among threads).
int * threadIDs = new int[P];
for (int i = 0; i < P; ++i)
threadIDs[i] = i;
// Start P new threads, each with different ID.
pthread_t * threads = new pthread_t[P];
for (int i = 0; i < P; ++i)
pthread_create(&threads[i], NULL, printHello,
(void *) &threadIDs[i]);
// Wait for all threads to complete.
for (int i = 0; i < P; ++i)
pthread_join(threads[i], NULL);
// Clean up and exit.
delete [] threadIDs;
delete [] threads;
cout << "That's all, folks!\n";
return EXIT_SUCCESS;
}
// ---- Code to be executed by each thread ---------------------------
// pre: *threadArg is an integer "thread ID".
// post: "hello" message printed to standard output.
// return value is null pointer.
void * printHello(void * threadArg) {
int * myID = (int *) threadArg;
cout << "hello, world, ";
// pointless pause, included to make the effects of
// synchronization (or lack thereof) more obvious
usleep(10);
cout << "from thread " << *myID << endl;
pthread_exit((void* ) NULL);
}
|
（以上所有代码均由 Moshe 以 Moshe Bar 或 Moshe 以 Qlusters, Inc. 首席技术官的身份编写。）
另请参阅 openMosix 的手册页，它们也充分解释了为什么进程不迁移。
如果由于某种原因，您的进程在不应该锁定的情况下保持锁定状态。您可以尝试通过简单地放入以下内容来允许锁定的进程迁移：
# tell shells to allow subprocs to migrate to other nodes echo 0 > /proc/self/lock |