[linux-2.6-block.git] / arch / mips / kernel / mips-mt-fpaff.c

/*
 * General MIPS MT support routines, usable in AP/SP, SMVP, or SMTC kernels
 * Copyright (C) 2005 Mips Technologies, Inc
 */
#include <linux/cpu.h>
#include <linux/cpumask.h>
#include <linux/delay.h>
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/sched.h>
#include <linux/security.h>
#include <linux/types.h>
#include <asm/uaccess.h>

/*
 * CPU mask used to set process affinity for MT VPEs/TCs with FPUs
 */
cpumask_t mt_fpu_cpumask;

static int fpaff_threshold = -1;
unsigned long mt_fpemul_threshold = 0;

/*
 * Replacement functions for the sys_sched_setaffinity() and
 * sys_sched_getaffinity() system calls, so that we can integrate
 * FPU affinity with the user's requested processor affinity.
 * This code is 98% identical with the sys_sched_setaffinity()
 * and sys_sched_getaffinity() system calls, and should be
 * updated when kernel/sched.c changes.
 */

/*
 * find_process_by_pid - find a process with a matching PID value.
 * used in sys_sched_set/getaffinity() in kernel/sched.c, so
 * cloned here.
 */
static inline struct task_struct *find_process_by_pid(pid_t pid)
{
	return pid ? find_task_by_pid(pid) : current;
}


/*
 * mipsmt_sys_sched_setaffinity - set the cpu affinity of a process
 */
asmlinkage long mipsmt_sys_sched_setaffinity(pid_t pid, unsigned int len,
				      unsigned long __user *user_mask_ptr)
{
	cpumask_t new_mask;
	cpumask_t effective_mask;
	int retval;
	struct task_struct *p;
	struct thread_info *ti;

	if (len < sizeof(new_mask))
		return -EINVAL;

	if (copy_from_user(&new_mask, user_mask_ptr, sizeof(new_mask)))
		return -EFAULT;

	get_online_cpus();
	read_lock(&tasklist_lock);

	p = find_process_by_pid(pid);
	if (!p) {
		read_unlock(&tasklist_lock);
		put_online_cpus();
		return -ESRCH;
	}

	/*
	 * It is not safe to call set_cpus_allowed with the
	 * tasklist_lock held.  We will bump the task_struct's
	 * usage count and drop tasklist_lock before invoking
	 * set_cpus_allowed.
	 */
	get_task_struct(p);

	retval = -EPERM;
	if ((current->euid != p->euid) && (current->euid != p->uid) &&
			!capable(CAP_SYS_NICE)) {
		read_unlock(&tasklist_lock);
		goto out_unlock;
	}

	retval = security_task_setscheduler(p, 0, NULL);
	if (retval)
		goto out_unlock;

	/* Record new user-specified CPU set for future reference */
	p->thread.user_cpus_allowed = new_mask;

	/* Unlock the task list */
	read_unlock(&tasklist_lock);

	/* Compute new global allowed CPU set if necessary */
	ti = task_thread_info(p);
	if (test_ti_thread_flag(ti, TIF_FPUBOUND) &&
	    cpus_intersects(new_mask, mt_fpu_cpumask)) {
		cpus_and(effective_mask, new_mask, mt_fpu_cpumask);
		retval = set_cpus_allowed(p, effective_mask);
	} else {
		clear_ti_thread_flag(ti, TIF_FPUBOUND);
		retval = set_cpus_allowed(p, new_mask);
	}

out_unlock:
	put_task_struct(p);
	put_online_cpus();
	return retval;
}

/*
 * mipsmt_sys_sched_getaffinity - get the cpu affinity of a process
 */
asmlinkage long mipsmt_sys_sched_getaffinity(pid_t pid, unsigned int len,
				      unsigned long __user *user_mask_ptr)
{
	unsigned int real_len;
	cpumask_t mask;
	int retval;
	struct task_struct *p;

	real_len = sizeof(mask);
	if (len < real_len)
		return -EINVAL;

	get_online_cpus();
	read_lock(&tasklist_lock);

	retval = -ESRCH;
	p = find_process_by_pid(pid);
	if (!p)
		goto out_unlock;
	retval = security_task_getscheduler(p);
	if (retval)
		goto out_unlock;

	cpus_and(mask, p->thread.user_cpus_allowed, cpu_possible_map);

out_unlock:
	read_unlock(&tasklist_lock);
	put_online_cpus();
	if (retval)
		return retval;
	if (copy_to_user(user_mask_ptr, &mask, real_len))
		return -EFAULT;
	return real_len;
}


static int __init fpaff_thresh(char *str)
{
	get_option(&str, &fpaff_threshold);
	return 1;
}
__setup("fpaff=", fpaff_thresh);

/*
 * FPU Use Factor empirically derived from experiments on 34K
 */
#define FPUSEFACTOR 333

static __init int mt_fp_affinity_init(void)
{
	if (fpaff_threshold >= 0) {
		mt_fpemul_threshold = fpaff_threshold;
	} else {
		mt_fpemul_threshold =
			(FPUSEFACTOR * (loops_per_jiffy/(500000/HZ))) / HZ;
	}
	printk(KERN_DEBUG "FPU Affinity set after %ld emulations\n",
	       mt_fpemul_threshold);

	return 0;
}
arch_initcall(mt_fp_affinity_init);
Commit	Line	Data
295cbf6d RB	1	/*
	2	* General MIPS MT support routines, usable in AP/SP, SMVP, or SMTC kernels
	3	* Copyright (C) 2005 Mips Technologies, Inc
	4	*/
	5	#include <linux/cpu.h>
	6	#include <linux/cpumask.h>
	7	#include <linux/delay.h>
	8	#include <linux/kernel.h>
	9	#include <linux/init.h>
	10	#include <linux/sched.h>
	11	#include <linux/security.h>
	12	#include <linux/types.h>
	13	#include <asm/uaccess.h>
	14
	15	/*
	16	* CPU mask used to set process affinity for MT VPEs/TCs with FPUs
	17	*/
	18	cpumask_t mt_fpu_cpumask;
	19
	20	static int fpaff_threshold = -1;
	21	unsigned long mt_fpemul_threshold = 0;
	22
	23	/*
	24	* Replacement functions for the sys_sched_setaffinity() and
	25	* sys_sched_getaffinity() system calls, so that we can integrate
	26	* FPU affinity with the user's requested processor affinity.
	27	* This code is 98% identical with the sys_sched_setaffinity()
	28	* and sys_sched_getaffinity() system calls, and should be
	29	* updated when kernel/sched.c changes.
	30	*/
	31
	32	/*
	33	* find_process_by_pid - find a process with a matching PID value.
	34	* used in sys_sched_set/getaffinity() in kernel/sched.c, so
	35	* cloned here.
	36	*/
	37	static inline struct task_struct *find_process_by_pid(pid_t pid)
	38	{
	39	return pid ? find_task_by_pid(pid) : current;
	40	}
	41
	42
	43	/*
	44	* mipsmt_sys_sched_setaffinity - set the cpu affinity of a process
	45	*/
	46	asmlinkage long mipsmt_sys_sched_setaffinity(pid_t pid, unsigned int len,
	47	unsigned long __user *user_mask_ptr)
	48	{
	49	cpumask_t new_mask;
	50	cpumask_t effective_mask;
	51	int retval;
	52	struct task_struct *p;
293c5bd1	53	struct thread_info *ti;
295cbf6d RB	54
	55	if (len < sizeof(new_mask))
	56	return -EINVAL;
	57
	58	if (copy_from_user(&new_mask, user_mask_ptr, sizeof(new_mask)))
	59	return -EFAULT;
	60
86ef5c9a	61	get_online_cpus();
295cbf6d RB	62	read_lock(&tasklist_lock);
	63
	64	p = find_process_by_pid(pid);
	65	if (!p) {
	66	read_unlock(&tasklist_lock);
86ef5c9a	67	put_online_cpus();
295cbf6d RB	68	return -ESRCH;
	69	}
	70
	71	/*
	72	* It is not safe to call set_cpus_allowed with the
	73	* tasklist_lock held. We will bump the task_struct's
	74	* usage count and drop tasklist_lock before invoking
	75	* set_cpus_allowed.
	76	*/
	77	get_task_struct(p);
	78
	79	retval = -EPERM;
	80	if ((current->euid != p->euid) && (current->euid != p->uid) &&
	81	!capable(CAP_SYS_NICE)) {
	82	read_unlock(&tasklist_lock);
	83	goto out_unlock;
	84	}
	85
	86	retval = security_task_setscheduler(p, 0, NULL);
	87	if (retval)
	88	goto out_unlock;
	89
	90	/* Record new user-specified CPU set for future reference */
	91	p->thread.user_cpus_allowed = new_mask;
	92
	93	/* Unlock the task list */
	94	read_unlock(&tasklist_lock);
	95
	96	/* Compute new global allowed CPU set if necessary */
293c5bd1 RB	97	ti = task_thread_info(p);
	98	if (test_ti_thread_flag(ti, TIF_FPUBOUND) &&
	99	cpus_intersects(new_mask, mt_fpu_cpumask)) {
295cbf6d RB	100	cpus_and(effective_mask, new_mask, mt_fpu_cpumask);
	101	retval = set_cpus_allowed(p, effective_mask);
	102	} else {
293c5bd1	103	clear_ti_thread_flag(ti, TIF_FPUBOUND);
295cbf6d RB	104	retval = set_cpus_allowed(p, new_mask);
	105	}
	106
295cbf6d RB	107	out_unlock:
295cbf6d RB	108	put_task_struct(p);
86ef5c9a	109	put_online_cpus();
295cbf6d RB	110	return retval;
	111	}
	112
	113	/*
	114	* mipsmt_sys_sched_getaffinity - get the cpu affinity of a process
	115	*/
	116	asmlinkage long mipsmt_sys_sched_getaffinity(pid_t pid, unsigned int len,
	117	unsigned long __user *user_mask_ptr)
	118	{
	119	unsigned int real_len;
	120	cpumask_t mask;
	121	int retval;
	122	struct task_struct *p;
	123
	124	real_len = sizeof(mask);
	125	if (len < real_len)
	126	return -EINVAL;
	127
86ef5c9a	128	get_online_cpus();
295cbf6d RB	129	read_lock(&tasklist_lock);
	130
	131	retval = -ESRCH;
	132	p = find_process_by_pid(pid);
	133	if (!p)
	134	goto out_unlock;
	135	retval = security_task_getscheduler(p);
	136	if (retval)
	137	goto out_unlock;
	138
	139	cpus_and(mask, p->thread.user_cpus_allowed, cpu_possible_map);
	140
	141	out_unlock:
	142	read_unlock(&tasklist_lock);
86ef5c9a	143	put_online_cpus();
295cbf6d RB	144	if (retval)
	145	return retval;
	146	if (copy_to_user(user_mask_ptr, &mask, real_len))
	147	return -EFAULT;
	148	return real_len;
	149	}
	150
	151
	152	static int __init fpaff_thresh(char *str)
	153	{
	154	get_option(&str, &fpaff_threshold);
	155	return 1;
	156	}
	157	__setup("fpaff=", fpaff_thresh);
	158
	159	/*
	160	* FPU Use Factor empirically derived from experiments on 34K
	161	*/
	162	#define FPUSEFACTOR 333
	163
	164	static __init int mt_fp_affinity_init(void)
	165	{
	166	if (fpaff_threshold >= 0) {
	167	mt_fpemul_threshold = fpaff_threshold;
	168	} else {
	169	mt_fpemul_threshold =
	170	(FPUSEFACTOR * (loops_per_jiffy/(500000/HZ))) / HZ;
	171	}
	172	printk(KERN_DEBUG "FPU Affinity set after %ld emulations\n",
	173	mt_fpemul_threshold);
	174
	175	return 0;
	176	}
	177	arch_initcall(mt_fp_affinity_init);