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 #include <stddef.h>
  19 #include <unistd.h>
  20
  21 #include "defaults.h"
  22 #include "macros.h"
  23
  24 size_t default_channel_subbuf_size;
  25 size_t default_metadata_subbuf_size;
  26 size_t default_kernel_channel_subbuf_size;
  27 size_t default_ust_pid_channel_subbuf_size;
  28 size_t default_ust_uid_channel_subbuf_size;
  29
  30 static void __attribute__((constructor)) init_defaults(void)
  31 {
  32         /*
  33          * The libringbuffer won't accept subbuf sizes smaller than the page size.
  34          * If the default subbuf size is smaller, replace it by the page size.
  35          */
  36         long page_size = sysconf(_SC_PAGESIZE);
  37
  38         if (page_size < 0) {
  39                 page_size = 0;
  40         }
  41
  42         default_channel_subbuf_size =
  43                 max(_DEFAULT_CHANNEL_SUBBUF_SIZE, page_size);
  44         default_metadata_subbuf_size =
  45                 max(DEFAULT_METADATA_SUBBUF_SIZE, page_size);
  46         default_kernel_channel_subbuf_size =
  47                 max(DEFAULT_KERNEL_CHANNEL_SUBBUF_SIZE, page_size);
  48         default_ust_pid_channel_subbuf_size =
  49                 max(DEFAULT_UST_PID_CHANNEL_SUBBUF_SIZE, page_size);
  50         default_ust_uid_channel_subbuf_size =
  51                 max(DEFAULT_UST_UID_CHANNEL_SUBBUF_SIZE, page_size);
  52 }