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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>3=2n#<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)
{
int prio = ((int)TT.class << 13) | (int)TT.level;
return syscall(__NR_ioprio_set, 1, (int)TT.pid, prio);
}
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");
}
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