diff options
Diffstat (limited to 'kernel/pid.c')
| -rw-r--r-- | kernel/pid.c | 49 |
1 files changed, 38 insertions, 11 deletions
diff --git a/kernel/pid.c b/kernel/pid.c index ed6adbba677b..f5afb3137e74 100644 --- a/kernel/pid.c +++ b/kernel/pid.c @@ -23,10 +23,11 @@ #include <linux/slab.h> #include <linux/init.h> #include <linux/bootmem.h> +#include <linux/hash.h> -#define PIDHASH_SIZE 4096 -#define pid_hashfn(nr) ((nr >> 8) ^ nr) & (PIDHASH_SIZE - 1) -static struct list_head pid_hash[PIDTYPE_MAX][PIDHASH_SIZE]; +#define pid_hashfn(nr) hash_long((unsigned long)nr, pidhash_shift) +static struct list_head *pid_hash[PIDTYPE_MAX]; +static int pidhash_shift; int pid_max = PID_MAX_DEFAULT; int last_pid; @@ -258,20 +259,46 @@ void switch_exec_pids(task_t *leader, task_t *thread) attach_pid(leader, PIDTYPE_SID, leader->session); } +/* + * The pid hash table is scaled according to the amount of memory in the + * machine. From a minimum of 16 slots up to 4096 slots at one gigabyte or + * more. + */ void __init pidhash_init(void) { - int i, j; + int i, j, pidhash_size; + unsigned long megabytes = max_pfn >> (20 - PAGE_SHIFT); + + pidhash_shift = max(4, fls(megabytes * 4)); + pidhash_shift = min(12, pidhash_shift); + pidhash_size = 1 << pidhash_shift; + + printk("PID hash table entries: %d (order %d: %Zd bytes)\n", + pidhash_size, pidhash_shift, + pidhash_size * sizeof(struct list_head)); + + for (i = 0; i < PIDTYPE_MAX; i++) { + pid_hash[i] = alloc_bootmem(pidhash_size * + sizeof(struct list_head)); + if (!pid_hash[i]) + panic("Could not alloc pidhash!\n"); + for (j = 0; j < pidhash_size; j++) + INIT_LIST_HEAD(&pid_hash[i][j]); + } +} + +void __init pidmap_init(void) +{ + int i; - /* - * Allocate PID 0, and hash it via all PID types: - */ pidmap_array->page = (void *)get_zeroed_page(GFP_KERNEL); set_bit(0, pidmap_array->page); atomic_dec(&pidmap_array->nr_free); - for (i = 0; i < PIDTYPE_MAX; i++) { - for (j = 0; j < PIDHASH_SIZE; j++) - INIT_LIST_HEAD(&pid_hash[i][j]); + /* + * Allocate PID 0, and hash it via all PID types: + */ + + for (i = 0; i < PIDTYPE_MAX; i++) attach_pid(current, i, 0); - } } |