1 files changed, 81 insertions, 0 deletions
diff --git a/toys/other/chrt.c b/toys/other/chrt.c
new file mode 100644
index 00000000..aa0a140d
--- /dev/null
+++ b/toys/other/chrt.c
@@ -0,0 +1,81 @@
+/* chrt.c - Get/set real-time (scheduling) attributes
+ *
+ * Copyright 2016 The Android Open Source Project
+ *
+ * Note: -ibrfo flags sorted to match SCHED positions for highest_bit()
+
+USE_CHRT(NEWTOY(chrt, "^mp#<0iRbrfo[!ibrfo]", TOYFLAG_USR|TOYFLAG_SBIN))
+
+config CHRT
+  bool "chrt"
+  default y
+  help
+    usage: chrt [-Rmofrbi] {-p PID [PRIORITY] | [PRIORITY COMMAND...]}
+
+    Get/set a process' real-time scheduling policy and priority.
+
+    -p	Set/query given pid (instead of running COMMAND)
+    -R	Set SCHED_RESET_ON_FORK
+    -m	Show min/max priorities available
+
+    Set policy (default -r):
+
+      -o  SCHED_OTHER    -f  SCHED_FIFO    -r  SCHED_RR
+      -b  SCHED_BATCH    -i  SCHED_IDLE
+*/
+
+#define FOR_chrt
+#include "toys.h"
+
+GLOBALS(
+  long pid;
+)
+
+char *polnames[] = {
+  "SCHED_OTHER", "SCHED_FIFO", "SCHED_RR", "SCHED_BATCH", 0, "SCHED_IDLE",
+  "SCHED_DEADLINE"
+};
+
+void chrt_main(void)
+{
+  int pol, pri;
+
+  // Show min/maxes?
+  if (toys.optflags&FLAG_m) {
+    for (pol = 0; pol<ARRAY_LEN(polnames); pol++) if (polnames[pol])
+      printf("%s min/max priority\t: %d/%d\n", polnames[pol],
+        sched_get_priority_min(pol), sched_get_priority_max(pol));
+
+    return;
+  }
+
+  // Query when -p without priority.
+  if (toys.optflags==FLAG_p && !*toys.optargs) {
+    char *s = "???", *R = "";
+
+    if (-1==(pol = sched_getscheduler(TT.pid))) perror_exit("pid %ld", TT.pid);
+    if (pol & SCHED_RESET_ON_FORK) R = "|SCHED_RESET_ON_FORK";
+    if ((pol &= ~SCHED_RESET_ON_FORK)<ARRAY_LEN(polnames)) s = polnames[pol];
+    printf("pid %ld's current scheduling policy: %s%s\n", TT.pid, s, R);
+
+    if (sched_getparam(TT.pid, (void *)&pri)) perror_exit("sched_getparam");
+    printf("pid %ld's current scheduling priority: %d\n", TT.pid, pri);
+
+    return;
+  }
+
+  if (!*toys.optargs) help_exit("no PRIORITY");
+  if (!toys.optargs[1] == !(toys.optflags&FLAG_p))
+    help_exit("need 1 of -p or COMMAND");
+
+  // Set policy and priority
+  if (-1==(pol = highest_bit(toys.optflags&0x2f))) pol = SCHED_RR;
+  pri = atolx_range(*toys.optargs, sched_get_priority_min(pol),
+    sched_get_priority_max(pol));
+  if (toys.optflags&FLAG_R) pol |= SCHED_RESET_ON_FORK;
+
+  if (sched_setscheduler(TT.pid, pol, (void *)&pri))
+    perror_exit("sched_setscheduler");
+
+  if (*(toys.optargs+1)) xexec(toys.optargs+1);
+}