xref: /openbmc/linux/include/linux/threads.h (revision 5b91a75b)
1 /* SPDX-License-Identifier: GPL-2.0 */
2 #ifndef _LINUX_THREADS_H
3 #define _LINUX_THREADS_H
4 
5 
6 /*
7  * The default limit for the nr of threads is now in
8  * /proc/sys/kernel/threads-max.
9  */
10 
11 /*
12  * Maximum supported processors.  Setting this smaller saves quite a
13  * bit of memory.  Use nr_cpu_ids instead of this except for static bitmaps.
14  */
15 #ifndef CONFIG_NR_CPUS
16 /* FIXME: This should be fixed in the arch's Kconfig */
17 #define CONFIG_NR_CPUS	1
18 #endif
19 
20 /* Places which use this should consider cpumask_var_t. */
21 #define NR_CPUS		CONFIG_NR_CPUS
22 
23 #define MIN_THREADS_LEFT_FOR_ROOT 4
24 
25 /*
26  * This controls the default maximum pid allocated to a process
27  */
28 #define PID_MAX_DEFAULT (CONFIG_BASE_SMALL ? 0x1000 : 0x8000)
29 
30 /*
31  * A maximum of 4 million PIDs should be enough for a while.
32  * [NOTE: PID/TIDs are limited to 2^30 ~= 1 billion, see FUTEX_TID_MASK.]
33  */
34 #define PID_MAX_LIMIT (CONFIG_BASE_SMALL ? PAGE_SIZE * 8 : \
35 	(sizeof(long) > 4 ? 4 * 1024 * 1024 : PID_MAX_DEFAULT))
36 
37 /*
38  * Define a minimum number of pids per cpu.  Heuristically based
39  * on original pid max of 32k for 32 cpus.  Also, increase the
40  * minimum settable value for pid_max on the running system based
41  * on similar defaults.  See kernel/pid.c:pid_idr_init() for details.
42  */
43 #define PIDS_PER_CPU_DEFAULT	1024
44 #define PIDS_PER_CPU_MIN	8
45 
46 #endif
47