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ef0e76cc2

Denys Vlasenko
Denys Vlasenko
2017-01-29
SUCCESS Duration: 196s

Subject

taskset: rewrite to be task size-agnostic

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Architecture & Compiler Flags

Architecture: x86_64-linux-gnu Compiler: gcc (Ubuntu 11.4.0-1ubuntu1~22.04.3) 11.4.0

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Commit Diff GitHub →

miscutils/taskset.c +103 -102
miscutils/taskset.c+103 -102
@@ -8,7 +8,7 @@
//config:config TASKSET
//config: bool "taskset"
-//config: default n # doesn't build on some non-x86 targets (m68k)
+//config: default y
//config: help
//config: Retrieve or set a processes's CPU affinity.
//config: This requires sched_{g,s}etaffinity support in your libc.
@@ -18,15 +18,15 @@
//config: default y
//config: depends on TASKSET
//config: help
-//config: Add code for fancy output. This merely silences a compiler-warning
-//config: and adds about 135 Bytes. May be needed for machines with alot
-//config: of CPUs.
+//config: Needed for machines with more than 32-64 CPUs:
+//config: affinity parameter 0xHHHHHHHHHHHHHHHHHHHH can be arbitrarily long
+//config: in this case. Otherwise, it is limited to sizeof(long).
//applet:IF_TASKSET(APPLET(taskset, BB_DIR_USR_BIN, BB_SUID_DROP))
//kbuild:lib-$(CONFIG_TASKSET) += taskset.o
//usage:#define taskset_trivial_usage
-//usage: "[-p] [MASK] [PID | PROG ARGS]"
+//usage: "[-p] [HEXMASK] [PID | PROG ARGS]"
//usage:#define taskset_full_usage "\n\n"
//usage: "Set or get CPU affinity\n"
//usage: "\n -p Operate on an existing PID"
@@ -42,71 +42,80 @@
//usage: "$ taskset -p 1\n"
//usage: "pid 1's current affinity mask: 3\n"
/*
- Not yet implemented:
+ * Not yet implemented:
* -a/--all-tasks (affect all threads)
+ * needs to get TIDs from /proc/PID/task/ and use _them_ as "pid" in sched_setaffinity(pid)
* -c/--cpu-list (specify CPUs via "1,3,5-7")
*/
#include <sched.h>
#include "libbb.h"
+typedef unsigned long ul;
+#define SZOF_UL (unsigned)(sizeof(ul))
+#define BITS_UL (unsigned)(sizeof(ul)*8)
+#define MASK_UL (unsigned)(sizeof(ul)*8 - 1)
+
#if ENABLE_FEATURE_TASKSET_FANCY
#define TASKSET_PRINTF_MASK "%s"
/* craft a string from the mask */
-static char *from_cpuset(cpu_set_t *mask)
+static char *from_mask(const ul *mask, unsigned sz_in_bytes)
{
- int i;
- char *ret = NULL;
- char *str = xzalloc((CPU_SETSIZE / 4) + 1); /* we will leak it */
-
- for (i = CPU_SETSIZE - 4; i >= 0; i -= 4) {
- int val = 0;
- int off;
- for (off = 0; off <= 3; ++off)
- if (CPU_ISSET(i + off, mask))
- val |= 1 << off;
- if (!ret && val)
- ret = str;
- *str++ = bb_hexdigits_upcase[val] | 0x20;
+ char *str = xzalloc((sz_in_bytes+1) * 2); /* we will leak it */
+ char *p = str;
+ for (;;) {
+ ul v = *mask++;
+ if (SZOF_UL == 4)
+ p += sprintf(p, "%08lx", v);
+ if (SZOF_UL == 8)
+ p += sprintf(p, "%016lx", v);
+ if (SZOF_UL == 16)
+ p += sprintf(p, "%032lx", v); /* :) */
+ sz_in_bytes -= SZOF_UL;
+ if ((int)sz_in_bytes <= 0)
+ break;
}
- return ret;
+ while (str[0] == '0' && str[1])
+ str++;
+ return str;
}
#else
-#define TASKSET_PRINTF_MASK "%llx"
-static unsigned long long from_cpuset(cpu_set_t *mask)
+#define TASKSET_PRINTF_MASK "%lx"
+static unsigned long long from_mask(ul *mask, unsigned sz_in_bytes UNUSED_PARAM)
{
- BUILD_BUG_ON(CPU_SETSIZE < 8*sizeof(int));
-
- /* Take the least significant bits. Assume cpu_set_t is
- * implemented as an array of unsigned long or unsigned
- * int.
- */
- if (CPU_SETSIZE < 8*sizeof(long))
- return *(unsigned*)mask;
- if (CPU_SETSIZE < 8*sizeof(long long))
- return *(unsigned long*)mask;
-# if BB_BIG_ENDIAN
- if (sizeof(long long) > sizeof(long)) {
- /* We can put two long in the long long, but they have to
- * be swapped: the least significant word comes first in the
- * array */
- unsigned long *p = (void*)mask;
- return p[0] + ((unsigned long long)p[1] << (8*sizeof(long)));
- }
-# endif
- return *(unsigned long long*)mask;
+ return *mask;
}
#endif
+static unsigned long *get_aff(int pid, unsigned *sz)
+{
+ int r;
+ unsigned long *mask = NULL;
+ unsigned sz_in_bytes = *sz;
+
+ for (;;) {
+ mask = xrealloc(mask, sz_in_bytes);
+ r = sched_getaffinity(pid, sz_in_bytes, (void*)mask);
+ if (r == 0)
+ break;
+ sz_in_bytes *= 2;
+ if (errno == EINVAL && (int)sz_in_bytes > 0)
+ continue;
+ bb_perror_msg_and_die("can't %cet pid %d's affinity", 'g', pid);
+ }
+ //bb_error_msg("get mask[0]:%lx sz_in_bytes:%d", mask[0], sz_in_bytes);
+ *sz = sz_in_bytes;
+ return mask;
+}
int taskset_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
int taskset_main(int argc UNUSED_PARAM, char **argv)
{
- cpu_set_t mask;
+ ul *mask;
+ unsigned mask_size_in_bytes;
pid_t pid = 0;
unsigned opt_p;
const char *current_new;
- char *pid_str;
char *aff = aff; /* for compiler */
/* NB: we mimic util-linux's taskset: -p does not take
@@ -119,7 +128,7 @@ int taskset_main(int argc UNUSED_PARAM, char **argv)
argv += optind;
if (opt_p) {
- pid_str = *argv++;
+ char *pid_str = *argv++;
if (*argv) { /* "-p <aff> <pid> ...rest.is.ignored..." */
aff = pid_str;
pid_str = *argv; /* NB: *argv != NULL in this case */
@@ -132,13 +141,14 @@ int taskset_main(int argc UNUSED_PARAM, char **argv)
bb_show_usage();
}
+ mask_size_in_bytes = SZOF_UL;
+ mask = NULL;
current_new = "current\0new";
- if (opt_p) {
print_aff:
- if (sched_getaffinity(pid, sizeof(mask), &mask) < 0)
- bb_perror_msg_and_die("can't %cet pid %d's affinity", 'g', pid);
+ mask = get_aff(pid, &mask_size_in_bytes);
+ if (opt_p) {
printf("pid %d's %s affinity mask: "TASKSET_PRINTF_MASK"\n",
- pid, current_new, from_cpuset(&mask));
+ pid, current_new, from_mask(mask, mask_size_in_bytes));
if (!*argv) {
/* Either it was just "-p <pid>",
* or it was "-p <aff> <pid>" and we came here
@@ -148,72 +158,63 @@ int taskset_main(int argc UNUSED_PARAM, char **argv)
*argv = NULL;
current_new += 8; /* "new" */
}
+ memset(mask, 0, mask_size_in_bytes);
- /* Affinity was specified, translate it into cpu_set_t */
- CPU_ZERO(&mask);
- if (!ENABLE_FEATURE_TASKSET_FANCY) {
- unsigned i;
- unsigned long long m;
+ /* Affinity was specified, translate it into mask */
+ /* it is always in hex, skip "0x" if it exists */
+ if (aff[0] == '0' && (aff[1]|0x20) == 'x')
+ aff += 2;
+ if (!ENABLE_FEATURE_TASKSET_FANCY) {
/* Do not allow zero mask: */
- m = xstrtoull_range(aff, 0, 1, ULLONG_MAX);
- i = 0;
- do {
- if (m & 1)
- CPU_SET(i, &mask);
- i++;
- m >>= 1;
- } while (m != 0);
+ mask[0] = xstrtoul_range(aff, 16, 1, ULONG_MAX);
} else {
unsigned i;
- char *last_byte;
- char *bin;
- uint8_t bit_in_byte;
-
- /* Cheap way to get "long enough" buffer */
- bin = xstrdup(aff);
-
- if (aff[0] != '0' || (aff[1]|0x20) != 'x') {
-/* TODO: decimal/octal masks are still limited to 2^64 */
- unsigned long long m = xstrtoull_range(aff, 0, 1, ULLONG_MAX);
- bin += strlen(bin);
- last_byte = bin - 1;
- while (m) {
- *--bin = m & 0xff;
- m >>= 8;
- }
- } else {
- /* aff is "0x.....", we accept very long masks in this form */
- last_byte = hex2bin(bin, aff + 2, INT_MAX);
- if (!last_byte) {
- bad_aff:
+ char *last_char;
+
+ i = 0; /* bit pos in mask[] */
+
+ /* aff is ASCII hex string, accept very long masks in this form.
+ * Process hex string AABBCCDD... to ulong mask[]
+ * from the rightmost nibble, which is least-significant.
+ * Bits not fitting into mask[] are ignored: (example: 1234
+ * in 12340000000000000000000000000000000000000ff)
+ */
+ last_char = strchrnul(aff, '\0');
+ while (last_char > aff) {
+ char c;
+ ul val;
+
+ last_char--;
+ c = *last_char;
+ if (isdigit(c))
+ val = c - '0';
+ else if ((c|0x20) >= 'a' && (c|0x20) <= 'f')
+ val = (c|0x20) - ('a' - 10);
+ else
bb_error_msg_and_die("bad affinity '%s'", aff);
- }
- last_byte--; /* now points to the last byte */
- }
- i = 0;
- bit_in_byte = 1;
- while (last_byte >= bin) {
- if (bit_in_byte & *last_byte) {
- if (i >= CPU_SETSIZE)
- goto bad_aff;
- CPU_SET(i, &mask);
+ if (i < mask_size_in_bytes * 8) {
+ mask[i / BITS_UL] |= val << (i & MASK_UL);
//bb_error_msg("bit %d set", i);
}
- i++;
- /* bit_in_byte is uint8_t! & 0xff is implied */
- bit_in_byte = (bit_in_byte << 1);
- if (!bit_in_byte) {
- bit_in_byte = 1;
- last_byte--;
- }
+ /* else:
+ * We can error out here, but we don't.
+ * For one, kernel itself ignores bits in mask[]
+ * which do not map to any CPUs.
+ * If mask has one 32-bit long,
+ * but you have only 8 CPUs, all bits beyond first 8
+ * are ignored, silently.
+ * No point in making bits past 31th to be errors.
+ */
+ i += 4;
}
}
/* Set pid's or our own (pid==0) affinity */
- if (sched_setaffinity(pid, sizeof(mask), &mask))
+ if (sched_setaffinity(pid, mask_size_in_bytes, (void*)mask))
bb_perror_msg_and_die("can't %cet pid %d's affinity", 's', pid);
+ //bb_error_msg("set mask[0]:%lx", mask[0]);
if (!argv[0]) /* "-p <aff> <pid> [...ignored...]" */
goto print_aff; /* print new affinity and exit */