[PATCH 4/4] chrt: don't rely on exact values of SCHED_* defines
---
util-linux/chrt.c | 29 -
1 file changed, 16 insertions(+), 13 deletions(-)
diff --git a/util-linux/chrt.c b/util-linux/chrt.c
index 5c5513aeb..8fd4b7bea 100644
--- a/util-linux/chrt.c
+++ b/util-linux/chrt.c
@@ -36,17 +36,20 @@
#include
#include "libbb.h"
-static const struct {
- int policy;
- char name[sizeof("SCHED_OTHER")];
-} policies[] = {
- {SCHED_OTHER, "SCHED_OTHER"},
- {SCHED_FIFO, "SCHED_FIFO"},
- {SCHED_RR, "SCHED_RR"},
- {SCHED_BATCH, "SCHED_BATCH"},
- {0 /* unused */, ""},
- {SCHED_IDLE, "SCHED_IDLE"}
-};
+static const char* get_policy_name(int pol)
+{
+ if (pol == SCHED_OTHER)
+ return "SCHED_OTHER";
+ if (pol == SCHED_FIFO)
+ return "SCHED_FIFO";
+ if (pol == SCHED_RR)
+ return "SCHED_RR";
+ if (pol == SCHED_BATCH)
+ return "SCHED_BATCH";
+ if (pol == SCHED_IDLE)
+ return "SCHED_IDLE";
+ return "";
+}
static void show_min_max(int pol)
{
@@ -57,7 +60,7 @@ static void show_min_max(int pol)
min = sched_get_priority_min(pol);
if ((max|min) < 0)
fmt = "%s not supported\n";
- printf(fmt, policies[pol].name, min, max);
+ printf(fmt, get_policy_name(pol), min, max);
}
#define OPT_m (1<<0)
@@ -127,7 +130,7 @@ int chrt_main(int argc UNUSED_PARAM, char **argv)
if (pol < 0)
bb_perror_msg_and_die("can't %cet pid %d's policy",
'g', (int)pid);
printf("pid %d's %s scheduling policy: %s\n",
- pid, current_new, policies[pol].name);
+ pid, current_new, get_policy_name(pol));
if (sched_getparam(pid, &sp))
bb_perror_msg_and_die("can't get pid %d's attributes",
(int)pid);
printf("pid %d's %s scheduling priority: %d\n",
--
2.14.1
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[PATCH 0/4] Add SCHED_BATCH and SCHED_IDLE support to chrt
Hi, The following patches add SCHED_BATCH and SCHED_IDLE support to chrt. The priority limits are fixed to follow the specification. The last patch avoids hardcoding the values of SCHED_* macros as array indices. Perhaps counter-intuitively, this leads to binary size reduction of 90 bytes on x86-64. However the patch series as a whole still increase the binary size by 173 bytes on x86-64. Regards, Povilas ___ busybox mailing list busybox@busybox.net http://lists.busybox.net/mailman/listinfo/busybox
[PATCH 1/4] chrt: add support for SCHED_BATCH
---
util-linux/chrt.c | 16 +++-
1 file changed, 11 insertions(+), 5 deletions(-)
diff --git a/util-linux/chrt.c b/util-linux/chrt.c
index 2712ea3e3..e7abd4f5a 100644
--- a/util-linux/chrt.c
+++ b/util-linux/chrt.c
@@ -17,13 +17,14 @@
//kbuild:lib-$(CONFIG_CHRT) += chrt.o
//usage:#define chrt_trivial_usage
-//usage: "[-prfom] [PRIO] [PID | PROG ARGS]"
+//usage: "[-prfomb] [PRIO] [PID | PROG ARGS]"
//usage:#define chrt_full_usage "\n\n"
//usage: "Change scheduling priority and class for a process\n"
//usage: "\n -p Operate on PID"
//usage: "\n -r Set SCHED_RR class"
//usage: "\n -f Set SCHED_FIFO class"
//usage: "\n -o Set SCHED_OTHER class"
+//usage: "\n -b Set SCHED_BATCH class"
//usage: "\n -m Show min/max priorities"
//usage:
//usage:#define chrt_example_usage
@@ -40,11 +41,11 @@ static const struct {
} policies[] = {
{SCHED_OTHER, "SCHED_OTHER"},
{SCHED_FIFO, "SCHED_FIFO"},
- {SCHED_RR, "SCHED_RR"}
+ {SCHED_RR, "SCHED_RR"},
+ {SCHED_BATCH, "SCHED_BATCH"}
};
//TODO: add
-// -b, SCHED_BATCH
// -i, SCHED_IDLE
static void show_min_max(int pol)
@@ -64,6 +65,7 @@ static void show_min_max(int pol)
#define OPT_r (1<<2)
#define OPT_f (1<<3)
#define OPT_o (1<<4)
+#define OPT_b (1<<5)
int chrt_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
int chrt_main(int argc UNUSED_PARAM, char **argv)
@@ -77,11 +79,12 @@ int chrt_main(int argc UNUSED_PARAM, char **argv)
int policy = SCHED_RR;
/* only one policy accepted */
- opt = getopt32(argv, "^+" "mprfo" "\0" "r--fo:f--ro:o--rf");
+ opt = getopt32(argv, "^+" "mprfob" "\0" "r--fob:f--rob:o--rfb:b--rfo");
if (opt & OPT_m) { /* print min/max and exit */
show_min_max(SCHED_FIFO);
show_min_max(SCHED_RR);
show_min_max(SCHED_OTHER);
+ show_min_max(SCHED_BATCH);
fflush_stdout_and_exit(EXIT_SUCCESS);
}
if (opt & OPT_r)
@@ -90,6 +93,8 @@ int chrt_main(int argc UNUSED_PARAM, char **argv)
policy = SCHED_FIFO;
if (opt & OPT_o)
policy = SCHED_OTHER;
+ if (opt & OPT_b)
+ policy = SCHED_BATCH;
argv += optind;
if (!argv[0])
@@ -136,7 +141,8 @@ int chrt_main(int argc UNUSED_PARAM, char **argv)
[...] SCHED_OTHER or SCHED_BATCH must be assigned static priority 0.
[...] SCHED_FIFO or SCHED_RR can have static priority in 1..99 range.
*/
- sp.sched_priority = xstrtou_range(priority, 0, policy != SCHED_OTHER ?
1 : 0, 99);
+ sp.sched_priority = xstrtou_range(priority, 0,
+ (policy != SCHED_OTHER && policy != SCHED_BATCH) ? 1 :
0, 99);
if (sched_setscheduler(pid, policy, &sp) < 0)
bb_perror_msg_and_die("can't %cet pid %d's policy", 's',
(int)pid);
--
2.14.1
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[PATCH 2/4] chrt: add support for SCHED_IDLE
---
util-linux/chrt.c | 21 +
1 file changed, 13 insertions(+), 8 deletions(-)
diff --git a/util-linux/chrt.c b/util-linux/chrt.c
index e7abd4f5a..bbd6e2deb 100644
--- a/util-linux/chrt.c
+++ b/util-linux/chrt.c
@@ -17,7 +17,7 @@
//kbuild:lib-$(CONFIG_CHRT) += chrt.o
//usage:#define chrt_trivial_usage
-//usage: "[-prfomb] [PRIO] [PID | PROG ARGS]"
+//usage: "[-prfombi] [PRIO] [PID | PROG ARGS]"
//usage:#define chrt_full_usage "\n\n"
//usage: "Change scheduling priority and class for a process\n"
//usage: "\n -p Operate on PID"
@@ -25,6 +25,7 @@
//usage: "\n -f Set SCHED_FIFO class"
//usage: "\n -o Set SCHED_OTHER class"
//usage: "\n -b Set SCHED_BATCH class"
+//usage: "\n -i Set SCHED_IDLE class"
//usage: "\n -m Show min/max priorities"
//usage:
//usage:#define chrt_example_usage
@@ -42,12 +43,11 @@ static const struct {
{SCHED_OTHER, "SCHED_OTHER"},
{SCHED_FIFO, "SCHED_FIFO"},
{SCHED_RR, "SCHED_RR"},
- {SCHED_BATCH, "SCHED_BATCH"}
+ {SCHED_BATCH, "SCHED_BATCH"},
+ {0 /* unused */, ""},
+ {SCHED_IDLE, "SCHED_IDLE"}
};
-//TODO: add
-// -i, SCHED_IDLE
-
static void show_min_max(int pol)
{
const char *fmt = "%s min/max priority\t: %u/%u\n";
@@ -66,6 +66,7 @@ static void show_min_max(int pol)
#define OPT_f (1<<3)
#define OPT_o (1<<4)
#define OPT_b (1<<5)
+#define OPT_i (1<<6)
int chrt_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
int chrt_main(int argc UNUSED_PARAM, char **argv)
@@ -79,12 +80,13 @@ int chrt_main(int argc UNUSED_PARAM, char **argv)
int policy = SCHED_RR;
/* only one policy accepted */
- opt = getopt32(argv, "^+" "mprfob" "\0" "r--fob:f--rob:o--rfb:b--rfo");
+ opt = getopt32(argv, "^+" "mprfobi" "\0"
"r--fobi:f--robi:o--rfbi:b--rfoi:i--rfob");
if (opt & OPT_m) { /* print min/max and exit */
show_min_max(SCHED_FIFO);
show_min_max(SCHED_RR);
show_min_max(SCHED_OTHER);
show_min_max(SCHED_BATCH);
+ show_min_max(SCHED_IDLE);
fflush_stdout_and_exit(EXIT_SUCCESS);
}
if (opt & OPT_r)
@@ -95,6 +97,8 @@ int chrt_main(int argc UNUSED_PARAM, char **argv)
policy = SCHED_OTHER;
if (opt & OPT_b)
policy = SCHED_BATCH;
+ if (opt & OPT_i)
+ policy = SCHED_IDLE;
argv += optind;
if (!argv[0])
@@ -138,11 +142,12 @@ int chrt_main(int argc UNUSED_PARAM, char **argv)
/* from the manpage of sched_getscheduler:
[...] sched_priority can have a value in the range 0 to 99.
- [...] SCHED_OTHER or SCHED_BATCH must be assigned static priority 0.
+ [...] SCHED_OTHER, SCHED_BATCH or SCHED_IDLE must be assigned static
+ priority 0.
[...] SCHED_FIFO or SCHED_RR can have static priority in 1..99 range.
*/
sp.sched_priority = xstrtou_range(priority, 0,
- (policy != SCHED_OTHER && policy != SCHED_BATCH) ? 1 :
0, 99);
+ (policy != SCHED_OTHER && policy != SCHED_BATCH &&
policy != SCHED_IDLE) ? 1 : 0, 99);
if (sched_setscheduler(pid, policy, &sp) < 0)
bb_perror_msg_and_die("can't %cet pid %d's policy", 's',
(int)pid);
--
2.14.1
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[PATCH 3/4] chrt: fix incorrect maximum priority on SCHED_{OTHER,BATCH,IDLE}
---
util-linux/chrt.c | 14 --
1 file changed, 12 insertions(+), 2 deletions(-)
diff --git a/util-linux/chrt.c b/util-linux/chrt.c
index bbd6e2deb..5c5513aeb 100644
--- a/util-linux/chrt.c
+++ b/util-linux/chrt.c
@@ -78,6 +78,8 @@ int chrt_main(int argc UNUSED_PARAM, char **argv)
char *priority = priority; /* for compiler */
const char *current_new;
int policy = SCHED_RR;
+ int priority_min;
+ int priority_max;
/* only one policy accepted */
opt = getopt32(argv, "^+" "mprfobi" "\0"
"r--fobi:f--robi:o--rfbi:b--rfoi:i--rfob");
@@ -146,8 +148,16 @@ int chrt_main(int argc UNUSED_PARAM, char **argv)
priority 0.
[...] SCHED_FIFO or SCHED_RR can have static priority in 1..99 range.
*/
- sp.sched_priority = xstrtou_range(priority, 0,
- (policy != SCHED_OTHER && policy != SCHED_BATCH &&
policy != SCHED_IDLE) ? 1 : 0, 99);
+ if (policy == SCHED_OTHER || policy == SCHED_BATCH
+|| policy == SCHED_IDLE
+ ) {
+ priority_min = 0;
+ priority_max = 0;
+ } else {
+ priority_min = 1;
+ priority_max = 99;
+ }
+ sp.sched_priority = xstrtou_range(priority, 0, priority_min,
priority_max);
if (sched_setscheduler(pid, policy, &sp) < 0)
bb_perror_msg_and_die("can't %cet pid %d's policy", 's',
(int)pid);
--
2.14.1
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Re: [PATCH 4/4] chrt: don't rely on exact values of SCHED_* defines
On Sun, Jan 14, 2018 at 5:30 AM, Povilas Kanapickas wrote:
> --- a/util-linux/chrt.c
> +++ b/util-linux/chrt.c
> @@ -36,17 +36,20 @@
> #include
> #include "libbb.h"
>
> -static const struct {
> - int policy;
> - char name[sizeof("SCHED_OTHER")];
> -} policies[] = {
> - {SCHED_OTHER, "SCHED_OTHER"},
> - {SCHED_FIFO, "SCHED_FIFO"},
> - {SCHED_RR, "SCHED_RR"},
> - {SCHED_BATCH, "SCHED_BATCH"},
> - {0 /* unused */, ""},
> - {SCHED_IDLE, "SCHED_IDLE"}
> -};
> +static const char* get_policy_name(int pol)
> +{
> + if (pol == SCHED_OTHER)
> + return "SCHED_OTHER";
> + if (pol == SCHED_FIFO)
> + return "SCHED_FIFO";
> + if (pol == SCHED_RR)
> + return "SCHED_RR";
> + if (pol == SCHED_BATCH)
> + return "SCHED_BATCH";
> + if (pol == SCHED_IDLE)
> + return "SCHED_IDLE";
> + return "";
> +}
>
> static void show_min_max(int pol)
> {
I don't like the chain of "if"s here. Have you checked the size changes on the
compiled code?
Since this SCHED policy constants are just enum values, what about using
"switch-case" statement? The problem of if-chains is that some compilers are
not smart at figuring out that the comparisons are just enums and can be
optimized. The switch-case statement will make it more clear.
Sorry for nit-picking the code.
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