include/linux/threads.h

   1 #ifndef _LINUX_THREADS_H
   2 #define _LINUX_THREADS_H
   3
   4
   5 /*
   6  * The default limit for the nr of threads is now in
   7  * /proc/sys/kernel/threads-max.
   8  */
   9
  10 /*
  11  * Maximum supported processors.  Setting this smaller saves quite a
  12  * bit of memory.  Use nr_cpu_ids instead of this except for static bitmaps.
  13  */
  14 #ifndef CONFIG_NR_CPUS
  15 /* FIXME: This should be fixed in the arch's Kconfig */
  16 #define CONFIG_NR_CPUS  1
  17 #endif
  18
  19 /* Places which use this should consider cpumask_var_t. */
  20 #define NR_CPUS         CONFIG_NR_CPUS
  21
  22 #define MIN_THREADS_LEFT_FOR_ROOT 4
  23
  24 /*
  25  * This controls the default maximum pid allocated to a process
  26  */
  27 #define PID_MAX_DEFAULT (CONFIG_BASE_SMALL ? 0x1000 : 0x8000)
  28
  29 /*
  30  * A maximum of 4 million PIDs should be enough for a while.
  31  * [NOTE: PID/TIDs are limited to 2^29 ~= 500+ million, see futex.h.]
  32  */
  33 #define PID_MAX_LIMIT (CONFIG_BASE_SMALL ? PAGE_SIZE * 8 : \
  34         (sizeof(long) > 4 ? 4 * 1024 * 1024 : PID_MAX_DEFAULT))
  35
  36 /*
  37  * Define a minimum number of pids per cpu.  Heuristically based
  38  * on original pid max of 32k for 32 cpus.  Also, increase the
  39  * minimum settable value for pid_max on the running system based
  40  * on similar defaults.  See kernel/pid.c:pidmap_init() for details.
  41  */
  42 #define PIDS_PER_CPU_DEFAULT    1024
  43 #define PIDS_PER_CPU_MIN        8
  44
  45 #endif