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libosmocore/src/vty/cpu_sched_vty.c

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/*! \file cpu_sched_vty.c
* Implementation to CPU / Threading / Scheduler properties from VTY configuration.
*/
/* (C) 2020 by sysmocom - s.f.m.c. GmbH <info@sysmocom.de>
*
* Author: Pau Espin Pedrol <pespin@sysmocom.de>
*
* All Rights Reserved
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*
* SPDX-License-Identifier: GPLv2+
*/
#define _GNU_SOURCE
#include "config.h"
#include <string.h>
#include <stdlib.h>
#include <errno.h>
#include <limits.h>
#include <unistd.h>
#include <sched.h>
#include <ctype.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <dirent.h>
#include <pthread.h>
#include <inttypes.h>
#include <osmocom/vty/vty.h>
#include <osmocom/vty/command.h>
#include <osmocom/vty/tdef_vty.h>
#include <osmocom/core/tdef.h>
#include <osmocom/core/fsm.h>
#include <osmocom/core/linuxlist.h>
/*! \addtogroup Tdef_VTY
*
* CPU Scheduling related VTY API.
*
* @{
* \file cpu_sched_vty.c
*/
enum sched_vty_thread_id {
SCHED_VTY_THREAD_SELF,
SCHED_VTY_THREAD_ALL,
SCHED_VTY_THREAD_ID,
SCHED_VTY_THREAD_NAME,
SCHED_VTY_THREAD_UNKNOWN,
};
struct cpu_affinity_it {
struct llist_head entry;
enum sched_vty_thread_id tid_type;
char bufname[64];
cpu_set_t *cpuset;
size_t cpuset_size;
bool delay;
};
struct sched_vty_opts {
void *tall_ctx;
int sched_rr_prio;
struct llist_head cpu_affinity_li;
pthread_mutex_t cpu_affinity_li_mutex;
};
static struct sched_vty_opts *sched_vty_opts;
static struct cmd_node sched_node = {
L_CPU_SCHED_NODE,
"%s(config-cpu-sched)# ",
1,
};
/* returns number of configured CPUs in the system, or negative otherwise */
static int get_num_cpus(void) {
static unsigned int num_cpus = 0;
long ln;
if (num_cpus)
return num_cpus;
/* This is expensive (goes across /sys, so let's do it only once. It is
* guaranteed it won't change during process span anyway). */
ln = sysconf(_SC_NPROCESSORS_CONF);
if (ln < 0) {
LOGP(DLGLOBAL, LOGL_ERROR, "sysconf(_SC_NPROCESSORS_CONF) failed: %s\n",
strerror(errno));
return -1;
}
num_cpus = (unsigned int) ln;
return num_cpus;
}
/* Parses string with CPU hex Affinity Mask, with right-most bit being CPU0, and
* fills a cpuset of size cpuset_size.
*/
static int parse_cpu_hex_mask(const char *str, cpu_set_t *cpuset, size_t cpuset_size)
{
int len = strlen(str);
const char *ptr = str + len - 1;
int cpu = 0;
/* skip optional '0x' prefix format */
if (len >= 2 && str[0] == '0' && str[1] == 'x')
str += 2;
CPU_ZERO_S(cpuset_size, cpuset);
while (ptr >= str) {
char c = *ptr;
uint8_t val;
if (c >= '0' && c <= '9') {
val = c - '0';
} else {
c = (char)tolower((int)c);
if (c >= 'a' && c <= 'f')
val = c + (10 - 'a');
else
return -1;
}
if (val & 0x01)
CPU_SET_S(cpu, cpuset_size, cpuset);
if (val & 0x02)
CPU_SET_S(cpu + 1, cpuset_size, cpuset);
if (val & 0x04)
CPU_SET_S(cpu + 2, cpuset_size, cpuset);
if (val & 0x08)
CPU_SET_S(cpu + 3, cpuset_size, cpuset);
ptr--;
cpu += 4;
}
return 0;
}
/* Generates a hexstring in str from cpuset of size cpuset_size */
static int generate_cpu_hex_mask(char *str, size_t str_buf_size,
cpu_set_t *cpuset, size_t cpuset_size)
{
char *ptr = str;
int cpu;
bool first_nonzero_found = false;
/* 2 char per byte, + '0x' prefix + '\0' */
if (cpuset_size * 2 + 2 + 1 > str_buf_size)
return -1;
*ptr++ = '0';
*ptr++ = 'x';
for (cpu = cpuset_size*8 - 4; cpu >= 0; cpu -= 4) {
uint8_t val = 0;
if (CPU_ISSET_S(cpu, cpuset_size, cpuset))
val |= 0x01;
if (CPU_ISSET_S(cpu + 1, cpuset_size, cpuset))
val |= 0x02;
if (CPU_ISSET_S(cpu + 2, cpuset_size, cpuset))
val |= 0x04;
if (CPU_ISSET_S(cpu + 3, cpuset_size, cpuset))
val |= 0x08;
if (val < 10)
*ptr = '0' + val;
else
*ptr = ('a' - 10) + val;
if (val)
first_nonzero_found = true;
if (first_nonzero_found)
ptr++;
}
if (!first_nonzero_found)
*ptr++ = '0';
*ptr = '\0';
return 0;
}
/* Checks whther a thread identified by tid exists and belongs to the running process */
static bool proc_tid_exists(pid_t tid)
{
DIR *proc_dir;
struct dirent *entry;
char dirname[100];
int tid_it;
bool found = false;
snprintf(dirname, sizeof(dirname), "/proc/%ld/task", (long int)getpid());
proc_dir = opendir(dirname);
if (!proc_dir)
return false; /*FIXME; print error */
while ((entry = readdir(proc_dir))) {
if (entry->d_name[0] == '.')
continue;
tid_it = atoi(entry->d_name);
if (tid_it == tid) {
found = true;
break;
}
}
closedir(proc_dir);
return found;
}
/* Checks whther a thread identified by name exists and belongs to the running
* process, and returns its disocevered TID in res_pid.
*/
static bool proc_name_exists(const char *name, pid_t *res_pid)
{
DIR *proc_dir;
struct dirent *entry;
char path[100];
char buf[17]; /* 15 + \n + \0 */
int tid_it;
int fd;
pid_t mypid = getpid();
bool found = false;
int rc;
*res_pid = 0;
snprintf(path, sizeof(path), "/proc/%ld/task", (long int)mypid);
proc_dir = opendir(path);
if (!proc_dir)
return false;
while ((entry = readdir(proc_dir)))
{
if (entry->d_name[0] == '.')
continue;
tid_it = atoi(entry->d_name);
snprintf(path, sizeof(path), "/proc/%ld/task/%ld/comm", (long int)mypid, (long int) tid_it);
if ((fd = open(path, O_RDONLY)) == -1)
continue;
rc = read(fd, buf, sizeof(buf) - 1);
if (rc >= 0) {
/* Last may char contain a '\n', get rid of it */
if (rc > 0 && buf[rc - 1] == '\n')
buf[rc - 1] = '\0';
else
buf[rc] = '\0';
if (strcmp(name, buf) == 0) {
*res_pid = tid_it;
found = true;
}
}
close(fd);
if (found)
break;
}
closedir(proc_dir);
return found;
}
/* Parse VTY THREADNAME variable, return its type and fill discovered res_pid if required */
static enum sched_vty_thread_id procname2pid(pid_t *res_pid, const char *str, bool applynow)
{
size_t i, len;
bool is_pid = true;
if (strcmp(str, "all") == 0) {
*res_pid = 0;
return SCHED_VTY_THREAD_ALL;
}
if (strcmp(str, "self") == 0) {
*res_pid = 0;
return SCHED_VTY_THREAD_SELF;
}
len = strlen(str);
for (i = 0; i < len; i++) {
if (!isdigit(str[i])) {
is_pid = false;
break;
}
}
if (is_pid) {
int64_t val;
if (osmo_str_to_int64(&val, str, 0, 0, INT64_MAX))
return SCHED_VTY_THREAD_UNKNOWN;
*res_pid = (pid_t)val;
if (*res_pid != val)
return SCHED_VTY_THREAD_UNKNOWN;
if (!applynow || proc_tid_exists(*res_pid))
return SCHED_VTY_THREAD_ID;
else
return SCHED_VTY_THREAD_UNKNOWN;
}
if (len > 15) {
/* Thread names only allow up to 15+1 null chars, see man pthread_setname_np */
return SCHED_VTY_THREAD_UNKNOWN;
}
if (applynow) {
if (proc_name_exists(str, res_pid))
return SCHED_VTY_THREAD_NAME;
else
return SCHED_VTY_THREAD_UNKNOWN;
} else {
/* assume a thread will be named after it */
*res_pid = 0;
return SCHED_VTY_THREAD_NAME;
}
}
/* Wrapper for sched_setaffinity applying to single thread or all threads in process based on tid_type. */
static int my_sched_setaffinity(enum sched_vty_thread_id tid_type, pid_t pid,
cpu_set_t *cpuset, size_t cpuset_size)
{
DIR *proc_dir;
struct dirent *entry;
char dirname[100];
char str_mask[1024];
int tid_it;
int rc = 0;
if (generate_cpu_hex_mask(str_mask, sizeof(str_mask), cpuset, cpuset_size) < 0)
str_mask[0] = '\0';
if (tid_type != SCHED_VTY_THREAD_ALL) {
LOGP(DLGLOBAL, LOGL_NOTICE, "Setting CPU affinity mask for tid %lu to: %s\n",
(unsigned long) pid, str_mask);
rc = sched_setaffinity(pid, sizeof(cpu_set_t), cpuset);
return rc;
}
snprintf(dirname, sizeof(dirname), "/proc/%ld/task", (long int)getpid());
proc_dir = opendir(dirname);
if (!proc_dir)
return -EINVAL;
while ((entry = readdir(proc_dir)))
{
if (entry->d_name[0] == '.')
continue;
tid_it = atoi(entry->d_name);
LOGP(DLGLOBAL, LOGL_NOTICE, "Setting CPU affinity mask for tid %lu to: %s\n",
(unsigned long) tid_it, str_mask);
rc = sched_setaffinity(tid_it, sizeof(cpu_set_t), cpuset);
if (rc == -1)
break;
}
closedir(proc_dir);
return rc;
}
DEFUN_ATTR(cfg_sched_cpu_affinity, cfg_sched_cpu_affinity_cmd,
"cpu-affinity (self|all|<0-4294967295>|THREADNAME) CPUHEXMASK [delay]",
"Set CPU affinity mask on a (group of) thread(s)\n"
"Set CPU affinity mask on thread running the VTY\n"
"Set CPU affinity mask on all process' threads\n"
"Set CPU affinity mask on a thread with specified PID\n"
"Set CPU affinity mask on a thread with specified thread name\n"
"CPU affinity mask\n"
"If set, delay applying the affinity mask now and let the app handle it at a later point\n",
CMD_ATTR_IMMEDIATE)
{
const char* str_who = argv[0];
const char *str_mask = argv[1];
bool applynow = (argc != 3);
int rc;
pid_t pid;
enum sched_vty_thread_id tid_type;
struct cpu_affinity_it *it, *it_next;
cpu_set_t *cpuset;
size_t cpuset_size;
tid_type = procname2pid(&pid, str_who, applynow);
if (tid_type == SCHED_VTY_THREAD_UNKNOWN) {
vty_out(vty, "%% Failed parsing target thread %s%s",
str_who, VTY_NEWLINE);
return CMD_WARNING;
}
if (tid_type == SCHED_VTY_THREAD_ID && !applynow) {
vty_out(vty, "%% It makes no sense to delay applying cpu-affinity on tid %lu%s",
(unsigned long)pid, VTY_NEWLINE);
return CMD_WARNING;
}
if (tid_type == SCHED_VTY_THREAD_ALL && !applynow) {
vty_out(vty, "%% It makes no sense to delay applying cpu-affinity on all threads%s",
VTY_NEWLINE);
return CMD_WARNING;
}
cpuset = CPU_ALLOC(get_num_cpus());
cpuset_size = CPU_ALLOC_SIZE(get_num_cpus());
if (parse_cpu_hex_mask(str_mask, cpuset, cpuset_size) < 0) {
vty_out(vty, "%% Failed parsing CPU Affinity Mask %s%s",
str_mask, VTY_NEWLINE);
CPU_FREE(cpuset);
return CMD_WARNING;
}
if (applynow) {
rc = my_sched_setaffinity(tid_type, pid, cpuset, cpuset_size);
if (rc == -1) {
vty_out(vty, "%% Failed setting sched CPU Affinity Mask %s: %s%s",
str_mask, strerror(errno), VTY_NEWLINE);
CPU_FREE(cpuset);
return CMD_WARNING;
}
}
/* Keep history of cmds applied to be able to rewrite config. If PID was passed
directly it makes no sense to store it since PIDs are temporary */
if (tid_type == SCHED_VTY_THREAD_SELF ||
tid_type == SCHED_VTY_THREAD_ALL ||
tid_type == SCHED_VTY_THREAD_NAME) {
pthread_mutex_lock(&sched_vty_opts->cpu_affinity_li_mutex);
/* Drop previous entries matching, since they will be overwritten */
llist_for_each_entry_safe(it, it_next, &sched_vty_opts->cpu_affinity_li, entry) {
if (strcmp(it->bufname, str_who) == 0) {
llist_del(&it->entry);
CPU_FREE(it->cpuset);
talloc_free(it);
break;
}
}
it = talloc_zero(sched_vty_opts->tall_ctx, struct cpu_affinity_it);
OSMO_STRLCPY_ARRAY(it->bufname, str_who);
it->tid_type = tid_type;
it->cpuset = cpuset;
it->cpuset_size = cpuset_size;
it->delay = !applynow;
llist_add_tail(&it->entry, &sched_vty_opts->cpu_affinity_li);
pthread_mutex_unlock(&sched_vty_opts->cpu_affinity_li_mutex);
} else {
/* We don't need cpuset for later, free it: */
CPU_FREE(cpuset);
}
return CMD_SUCCESS;
}
static int set_sched_rr(unsigned int prio)
{
struct sched_param param;
int rc;
memset(&param, 0, sizeof(param));
param.sched_priority = prio;
LOGP(DLGLOBAL, LOGL_NOTICE, "Setting SCHED_RR priority %d\n", param.sched_priority);
rc = sched_setscheduler(getpid(), SCHED_RR, &param);
if (rc == -1) {
LOGP(DLGLOBAL, LOGL_ERROR, "Setting SCHED_RR priority %d failed: %s\n",
param.sched_priority, strerror(errno));
return -1;
}
return 0;
}
DEFUN_ATTR(cfg_sched_policy, cfg_sched_policy_cmd,
"policy rr <1-32>",
"Set the scheduling policy to use for the process\n"
"Use the SCHED_RR real-time scheduling algorithm\n"
"Set the SCHED_RR real-time priority\n",
CMD_ATTR_IMMEDIATE)
{
sched_vty_opts->sched_rr_prio = atoi(argv[0]);
if (set_sched_rr(sched_vty_opts->sched_rr_prio) < 0) {
vty_out(vty, "%% Failed setting SCHED_RR priority %d%s",
sched_vty_opts->sched_rr_prio, VTY_NEWLINE);
return CMD_WARNING;
}
return CMD_SUCCESS;
}
DEFUN(cfg_sched,
cfg_sched_cmd,
"cpu-sched", "Configure CPU Scheduler related settings")
{
vty->index = NULL;
vty->node = L_CPU_SCHED_NODE;
return CMD_SUCCESS;
}
DEFUN(show_sched_threads, show_sched_threads_cmd,
"show cpu-sched threads",
SHOW_STR
"Show Sched section information\n"
"Show information about running threads)\n")
{
DIR *proc_dir;
struct dirent *entry;
char path[100];
char name[17];
char str_mask[1024];
int tid_it;
int fd;
pid_t mypid = getpid();
int rc;
cpu_set_t *cpuset;
size_t cpuset_size;
vty_out(vty, "Thread list for PID %lu:%s", (unsigned long) mypid, VTY_NEWLINE);
snprintf(path, sizeof(path), "/proc/%ld/task", (long int)mypid);
proc_dir = opendir(path);
if (!proc_dir) {
vty_out(vty, "%% Failed opening dir%s%s", path, VTY_NEWLINE);
return CMD_WARNING;
}
while ((entry = readdir(proc_dir)))
{
if (entry->d_name[0] == '.')
continue;
tid_it = atoi(entry->d_name);
snprintf(path, sizeof(path), "/proc/%ld/task/%ld/comm", (long int)mypid, (long int)tid_it);
if ((fd = open(path, O_RDONLY)) != -1) {
rc = read(fd, name, sizeof(name) - 1);
if (rc >= 0) {
/* Last may char contain a '\n', get rid of it */
if (rc > 0 && name[rc - 1] == '\n')
name[rc - 1] = '\0';
else
name[rc] = '\0';
}
close(fd);
} else {
name[0] = '\0';
}
str_mask[0] = '\0';
cpuset = CPU_ALLOC(get_num_cpus());
cpuset_size = CPU_ALLOC_SIZE(get_num_cpus());
CPU_ZERO_S(cpuset_size, cpuset);
if (sched_getaffinity(tid_it, cpuset_size, cpuset) == 0) {
if (generate_cpu_hex_mask(str_mask, sizeof(str_mask), cpuset, cpuset_size) < 0)
str_mask[0] = '\0';
}
CPU_FREE(cpuset);
vty_out(vty, " TID: %lu, NAME: '%s', cpu-affinity: %s%s",
(unsigned long) tid_it, name, str_mask, VTY_NEWLINE);
}
closedir(proc_dir);
return CMD_SUCCESS;
}
static int config_write_sched(struct vty *vty)
{
struct cpu_affinity_it *it;
char str_mask[1024];
/* Only add the node if there's something to write under it */
if (sched_vty_opts->sched_rr_prio || !llist_empty(&sched_vty_opts->cpu_affinity_li))
vty_out(vty, "cpu-sched%s", VTY_NEWLINE);
if (sched_vty_opts->sched_rr_prio)
vty_out(vty, " policy rr %d%s", sched_vty_opts->sched_rr_prio, VTY_NEWLINE);
llist_for_each_entry(it, &sched_vty_opts->cpu_affinity_li, entry) {
if (generate_cpu_hex_mask(str_mask, sizeof(str_mask), it->cpuset, it->cpuset_size) < 0)
OSMO_STRLCPY_ARRAY(str_mask, "ERROR");
vty_out(vty, " cpu-affinity %s %s%s%s", it->bufname, str_mask,
it->delay ? " delay" : "", VTY_NEWLINE);
}
return CMD_SUCCESS;
}
/*! Initialize sched VTY nodes
* \param[in] tall_ctx Talloc context to use internally by vty_sched subsystem.
* \return 0 on success, non-zero on error.
*/
int osmo_cpu_sched_vty_init(void *tall_ctx)
{
OSMO_ASSERT(!sched_vty_opts); /* assert only called once */
sched_vty_opts = talloc_zero(tall_ctx, struct sched_vty_opts);
sched_vty_opts->tall_ctx = tall_ctx;
INIT_LLIST_HEAD(&sched_vty_opts->cpu_affinity_li);
pthread_mutex_init(&sched_vty_opts->cpu_affinity_li_mutex, NULL);
install_lib_element(CONFIG_NODE, &cfg_sched_cmd);
install_node(&sched_node, config_write_sched);
install_lib_element(L_CPU_SCHED_NODE, &cfg_sched_policy_cmd);
install_lib_element(L_CPU_SCHED_NODE, &cfg_sched_cpu_affinity_cmd);
install_lib_element_ve(&show_sched_threads_cmd);
/* Initialize amount of cpus now */
if (get_num_cpus() < 0)
return -1;
return 0;
}
/*! Apply cpu-affinity on calling thread based on VTY configuration
* \return 0 on success, non-zero on error.
*/
int osmo_cpu_sched_vty_apply_localthread(void)
{
struct cpu_affinity_it *it, *it_match = NULL;
char name[16]; /* 15 + \0 */
char str_mask[1024];
bool has_name = false;
int rc = 0;
/* Assert subsystem was inited and structs are preset */
if (!sched_vty_opts) {
LOGP(DLGLOBAL, LOGL_FATAL, "Setting cpu-affinity mask impossible: no opts!\n");
return 0;
}
#ifdef HAVE_PTHREAD_GETNAME_NP
if (pthread_getname_np(pthread_self(), name, sizeof(name)) == 0)
has_name = true;
#endif
/* Get latest matching mask for the thread */
pthread_mutex_lock(&sched_vty_opts->cpu_affinity_li_mutex);
llist_for_each_entry(it, &sched_vty_opts->cpu_affinity_li, entry) {
switch (it->tid_type) {
case SCHED_VTY_THREAD_SELF:
continue; /* self to the VTY thread, not us */
case SCHED_VTY_THREAD_ALL:
it_match = it;
break;
case SCHED_VTY_THREAD_NAME:
if (!has_name)
continue;
if (strcmp(name, it->bufname) != 0)
continue;
it_match = it;
break;
default:
OSMO_ASSERT(0);
}
}
if (it_match) {
rc = my_sched_setaffinity(SCHED_VTY_THREAD_SELF, 0, it_match->cpuset, it_match->cpuset_size);
if (rc == -1) {
if (generate_cpu_hex_mask(str_mask, sizeof(str_mask),
it_match->cpuset, it_match->cpuset_size) < 0)
str_mask[0] = '\0';
LOGP(DLGLOBAL, LOGL_FATAL, "Setting cpu-affinity mask %s failed: %s\n",
str_mask, strerror(errno));
}
}
pthread_mutex_unlock(&sched_vty_opts->cpu_affinity_li_mutex);
return rc;
}
/*! @} */
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