1 files changed, 95 insertions, 0 deletions
diff --git a/toys/other/ionice.c b/toys/other/ionice.c
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+++ b/toys/other/ionice.c
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+/* ionice.c - set or get process I/O scheduling class and priority
+ *
+ * Copyright 2015 Rob Landley <rob@landley.net>
+ *
+ * It would be really nice if there was a standard, but no. There is
+ * Documentation/block/ioprio.txt in the linux source.
+
+USE_IONICE(NEWTOY(ionice, "^tc#<0>3n#<0>7=5p#", TOYFLAG_USR|TOYFLAG_BIN))
+USE_IORENICE(NEWTOY(iorenice, "?<1>3", TOYFLAG_USR|TOYFLAG_BIN))
+
+config IONICE
+  bool "ionice"
+  default y
+  help
+    usage: ionice [-t] [-c CLASS] [-n LEVEL] [COMMAND...|-p PID]
+
+    Change the I/O scheduling priority of a process. With no arguments
+    (or just -p), display process' existing I/O class/priority.
+
+    -c	CLASS = 1-3: 1(realtime), 2(best-effort, default), 3(when-idle)
+    -n	LEVEL = 0-7: (0 is highest priority, default = 5)
+    -p	Affect existing PID instead of spawning new child
+    -t	Ignore failure to set I/O priority
+
+    System default iopriority is generally -c 2 -n 4.
+
+config IORENICE
+  bool "iorenice"
+  default y
+  help
+    usage: iorenice PID [CLASS] [PRIORITY]
+
+    Display or change I/O priority of existing process. CLASS can be
+    "rt" for realtime, "be" for best effort, "idle" for only when idle, or
+    "none" to leave it alone. PRIORITY can be 0-7 (0 is highest, default 4).
+*/
+
+#define FOR_ionice
+#include "toys.h"
+#include <sys/syscall.h>
+
+GLOBALS(
+  long pid;
+  long level;
+  long class;
+)
+
+static int ioprio_get(void)
+{
+  return syscall(__NR_ioprio_get, 1, (int)TT.pid);
+}
+
+static int ioprio_set(void)
+{
+  return syscall(__NR_ioprio_set, 1, (int)TT.pid, (int)TT.class, (int)TT.level);
+}
+
+void ionice_main(void)
+{
+  if (!TT.pid && !toys.optc) error_exit("Need -p or COMMAND");
+  if (toys.optflags == FLAG_p) {
+    int p = ioprio_get();
+    xprintf("%s: prio %d\n",
+      (char *[]){"unknown", "Realtime", "Best-effort", "Idle"}[(p>>13)&3],
+      p&7);
+  } else {
+    if (-1 == ioprio_set() && !(toys.optflags&FLAG_t)) perror_exit("set");
+    if (TT.pid) xexec(toys.optargs);
+  }
+}
+
+void iorenice_main(void)
+{
+  char *classes[] = {"none", "rt", "be", "idle"};
+
+  TT.pid = atolx(*toys.optargs);
+  if (toys.optc == 1) {
+    int p = ioprio_get();
+
+    if (p == -1) perror_exit("read priority");
+    TT.class = (p>>13)&3;
+    p &= 7;
+    xprintf("Pid %d, class %s (%d), prio %d\n",
+            TT.pid, classes[TT.class], TT.class, p);
+    return;
+  }
+
+  for (TT.class = 0; TT.class<4; TT.class++)
+    if (!strcmp(toys.optargs[toys.optc-1], classes[TT.class])) break;
+  if (toys.optc == 3 || TT.class == 4) TT.level = atolx(toys.optargs[1]);
+  else TT.level = 4;
+  TT.class &= 3;
+
+  if (-1 == ioprio_set()) perror_exit("set");
+}