src/common/defaults.c

   1 /*
   2  * Copyright (C) 2012 - Simon Marchi <simon.marchi@polymtl.ca>
   3  *
   4  * This program is free software; you can redistribute it and/or modify it
   5  * under the terms of the GNU General Public License, version 2 only, as
   6  * published by the Free Software Foundation.
   7  *
   8  * This program is distributed in the hope that it will be useful, but WITHOUT
   9  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  10  * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
  11  * more details.
  12  *
  13  * You should have received a copy of the GNU General Public License along with
  14  * this program; if not, write to the Free Software Foundation, Inc., 51
  15  * Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  16  */
  17
  18 #define _LGPL_SOURCE
  19 #include <stddef.h>
  20 #include <unistd.h>
  21 #include <stdbool.h>
  22 #include <sys/resource.h>
  23 #include <pthread.h>
  24
  25 #include "defaults.h"
  26 #include "macros.h"
  27 #include "align.h"
  28 #include "error.h"
  29
  30 static int pthread_attr_init_done;
  31 static pthread_attr_t tattr;
  32
  33 LTTNG_HIDDEN
  34 size_t default_get_channel_subbuf_size(void)
  35 {
  36         return max(_DEFAULT_CHANNEL_SUBBUF_SIZE, PAGE_SIZE);
  37 }
  38
  39 LTTNG_HIDDEN
  40 size_t default_get_metadata_subbuf_size(void)
  41 {
  42         return max(DEFAULT_METADATA_SUBBUF_SIZE, PAGE_SIZE);
  43 }
  44
  45 LTTNG_HIDDEN
  46 size_t default_get_kernel_channel_subbuf_size(void)
  47 {
  48         return max(DEFAULT_KERNEL_CHANNEL_SUBBUF_SIZE, PAGE_SIZE);
  49 }
  50
  51 LTTNG_HIDDEN
  52 size_t default_get_ust_pid_channel_subbuf_size(void)
  53 {
  54         return max(DEFAULT_UST_PID_CHANNEL_SUBBUF_SIZE, PAGE_SIZE);
  55 }
  56
  57 LTTNG_HIDDEN
  58 size_t default_get_ust_uid_channel_subbuf_size(void)
  59 {
  60         return max(DEFAULT_UST_UID_CHANNEL_SUBBUF_SIZE, PAGE_SIZE);
  61 }
  62
  63 LTTNG_HIDDEN
  64 pthread_attr_t *default_pthread_attr(void)
  65 {
  66         if (pthread_attr_init_done) {
  67                 return &tattr;
  68         }
  69
  70         WARN("Uninitialized pthread attributes, using libc defaults.");
  71         return NULL;
  72 }
  73
  74 static void __attribute__((constructor)) init_default_pthread_attr(void)
  75 {
  76         int ret;
  77         struct rlimit rlim;
  78         size_t pthread_ss, system_ss, selected_ss;
  79
  80         ret = pthread_attr_init(&tattr);
  81         if (ret) {
  82                 errno = ret;
  83                 PERROR("pthread_attr_init");
  84                 goto error;
  85         }
  86
  87         /* Get system stack size limits. */
  88         ret = getrlimit(RLIMIT_STACK, &rlim);
  89         if (ret < 0) {
  90                 PERROR("getrlimit");
  91                 goto error_destroy;
  92         }
  93         DBG("Stack size limits: soft %lld, hard %lld bytes",
  94                         (long long) rlim.rlim_cur,
  95                         (long long) rlim.rlim_max);
  96
  97         /*
  98          * getrlimit() may return a stack size of "-1", meaning "unlimited".
  99          * In this case, we impose a known-good default minimum value which will
 100          * override the libc's default stack size if it is smaller.
 101          */
 102         system_ss = rlim.rlim_cur != -1 ? rlim.rlim_cur :
 103                         DEFAULT_LTTNG_THREAD_STACK_SIZE;
 104
 105         /* Get pthread default thread stack size. */
 106         ret = pthread_attr_getstacksize(&tattr, &pthread_ss);
 107         if (ret < 0) {
 108                 PERROR("pthread_attr_getstacksize");
 109                 goto error_destroy;
 110         }
 111         DBG("Default pthread stack size is %zu bytes", pthread_ss);
 112
 113         selected_ss = max_t(size_t, pthread_ss, system_ss);
 114         if (selected_ss < DEFAULT_LTTNG_THREAD_STACK_SIZE) {
 115                 DBG("Default stack size is too small, setting it to %zu bytes",
 116                         (size_t) DEFAULT_LTTNG_THREAD_STACK_SIZE);
 117                 selected_ss = DEFAULT_LTTNG_THREAD_STACK_SIZE;
 118         }
 119
 120         if (rlim.rlim_max > 0 && selected_ss > rlim.rlim_max) {
 121                 WARN("Your system's stack size restrictions (%zu bytes) may be too low for the LTTng daemons to function properly, please set the stack size limit to at leat %zu bytes to ensure reliable operation",
 122                         (size_t) rlim.rlim_max, (size_t) DEFAULT_LTTNG_THREAD_STACK_SIZE);
 123                 selected_ss = (size_t) rlim.rlim_max;
 124         }
 125
 126         ret = pthread_attr_setstacksize(&tattr, selected_ss);
 127         if (ret < 0) {
 128                 PERROR("pthread_attr_setstacksize");
 129                 goto error_destroy;
 130         }
 131         pthread_attr_init_done = 1;
 132 error:
 133         return;
 134 error_destroy:
 135         ret = pthread_attr_destroy(&tattr);
 136         if (ret) {
 137                 errno = ret;
 138                 PERROR("pthread_attr_destroy");
 139         }
 140 }
 141
 142 static void __attribute__((destructor)) fini_default_pthread_attr(void)
 143 {
 144         int ret;
 145
 146         if (!pthread_attr_init_done) {
 147                 return;
 148         }
 149
 150         ret = pthread_attr_destroy(&tattr);
 151         if (ret) {
 152                 errno = ret;
 153                 PERROR("pthread_attr_destroy");
 154         }
 155 }