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-rw-r--r--toys/other/taskset.c110
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diff --git a/toys/other/taskset.c b/toys/other/taskset.c
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+/* vi: set sw=4 ts=4:
+ *
+ * taskset.c - Retrieve or set the CPU affinity of a process.
+ *
+ * Copyright 2012 Elie De Brauwer <eliedebrauwer@gmail.com>
+ *
+ * No standard.
+
+USE_TASKSET(NEWTOY(taskset, "<1^pa", TOYFLAG_BIN|TOYFLAG_STAYROOT))
+
+config TASKSET
+ bool "taskset"
+ default y
+ help
+ usage: taskset [-ap] [mask] [PID | cmd [args...]]
+
+ Launch a new task which may only run on certain processors, or change
+ the processor affinity of an exisitng PID.
+
+ Mask is a hex string where each bit represents a processor the process
+ is allowed to run on. PID without a mask displays existing affinity.
+
+ -p Set/get the affinity of given PID instead of a new command.
+ -a Set/get the affinity of all threads of the PID.
+*/
+
+#include "toys.h"
+
+#define FLAG_a 0x1
+#define FLAG_p 0x2
+
+// Prototype for syscall wrappers sched.h refuses to give us
+int sched_setaffinity(pid_t pid, size_t size, void *cpuset);
+int sched_getaffinity(pid_t pid, size_t size, void *cpuset);
+
+// mask is an array of long, which makes the layout a bit weird on big
+// endian systems but as long as it's consistent...
+
+static void do_taskset(pid_t pid, int quiet)
+{
+ unsigned long *mask = (unsigned long *)toybuf;
+ char *s = *toys.optargs, *failed = "failed to %s %d's affinity";
+ int i, j, k;
+
+ for (i=0; ; i++) {
+ if (!quiet) {
+ int j = sizeof(toybuf), flag = 0;
+
+ if (sched_getaffinity(pid, sizeof(toybuf), (void *)mask))
+ perror_exit(failed, "get", pid);
+
+ printf("pid %d's %s affinity mask: ", pid, i ? "new" : "current");
+
+ while (j--) {
+ int x = 255 & (mask[j/sizeof(long)] >> (8*(j&(sizeof(long)-1))));
+
+ if (flag) printf("%02x", x);
+ else if (x) {
+ flag++;
+ printf("%x", x);
+ }
+ }
+ putchar('\n');
+ }
+
+ if (i || toys.optc < 2) return;
+
+ memset(toybuf, 0, sizeof(toybuf));
+ k = strlen(s = *toys.optargs);
+ s += k;
+ for (j = 0; j<k; j++) {
+ unsigned long digit = *(--s) - '0';
+
+ if (digit > 9) digit = 10 + tolower(*s)-'a';
+ if (digit > 15) error_exit("bad mask '%s'", *toys.optargs);
+ mask[j/(2*sizeof(long))] |= digit << 4*(j&((2*sizeof(long))-1));
+ }
+
+ if (sched_setaffinity(pid, sizeof(toybuf), (void *)mask))
+ perror_exit(failed, "set", pid);
+ }
+}
+
+static int task_callback(struct dirtree *new)
+{
+ if (!new->parent) return DIRTREE_RECURSE;
+ if (isdigit(*new->name)) do_taskset(atoi(new->name), 0);
+
+ return 0;
+}
+
+void taskset_main(void)
+{
+ if (!(toys.optflags & FLAG_p)) {
+ if (toys.optc < 2) error_exit("Needs 2 args");
+ do_taskset(getpid(), 1);
+ xexec(toys.optargs+1);
+ } else {
+ char *c;
+ pid_t pid = strtol(toys.optargs[toys.optc-1], &c, 10);
+
+ if (*c) error_exit("Not int %s", toys.optargs[1]);
+
+ if (toys.optflags & FLAG_a) {
+ char buf[33];
+ sprintf(buf, "/proc/%ld/task/", (long)pid);
+ dirtree_read(buf, task_callback);
+ } else do_taskset(pid, 0);
+ }
+}