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Ralf Baechle
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Ralf Baechle
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Jul 10, 2007
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--- | ||
refs/heads/master: 5ddcb3c35be995517a32799796e2acda90a784e0 | ||
refs/heads/master: 295cbf6d63165fe4253cf1d9ceadcda47a318b48 |
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/* | ||
* 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> | ||
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/* | ||
* CPU mask used to set process affinity for MT VPEs/TCs with FPUs | ||
*/ | ||
cpumask_t mt_fpu_cpumask; | ||
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static int fpaff_threshold = -1; | ||
unsigned long mt_fpemul_threshold = 0; | ||
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/* | ||
* 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. | ||
*/ | ||
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/* | ||
* 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; | ||
} | ||
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/* | ||
* 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; | ||
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if (len < sizeof(new_mask)) | ||
return -EINVAL; | ||
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if (copy_from_user(&new_mask, user_mask_ptr, sizeof(new_mask))) | ||
return -EFAULT; | ||
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lock_cpu_hotplug(); | ||
read_lock(&tasklist_lock); | ||
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p = find_process_by_pid(pid); | ||
if (!p) { | ||
read_unlock(&tasklist_lock); | ||
unlock_cpu_hotplug(); | ||
return -ESRCH; | ||
} | ||
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/* | ||
* 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); | ||
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retval = -EPERM; | ||
if ((current->euid != p->euid) && (current->euid != p->uid) && | ||
!capable(CAP_SYS_NICE)) { | ||
read_unlock(&tasklist_lock); | ||
goto out_unlock; | ||
} | ||
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retval = security_task_setscheduler(p, 0, NULL); | ||
if (retval) | ||
goto out_unlock; | ||
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/* Record new user-specified CPU set for future reference */ | ||
p->thread.user_cpus_allowed = new_mask; | ||
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/* Unlock the task list */ | ||
read_unlock(&tasklist_lock); | ||
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/* Compute new global allowed CPU set if necessary */ | ||
if ((p->thread.mflags & MF_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 { | ||
p->thread.mflags &= ~MF_FPUBOUND; | ||
retval = set_cpus_allowed(p, new_mask); | ||
} | ||
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out_unlock: | ||
put_task_struct(p); | ||
unlock_cpu_hotplug(); | ||
return retval; | ||
} | ||
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/* | ||
* 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; | ||
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real_len = sizeof(mask); | ||
if (len < real_len) | ||
return -EINVAL; | ||
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lock_cpu_hotplug(); | ||
read_lock(&tasklist_lock); | ||
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retval = -ESRCH; | ||
p = find_process_by_pid(pid); | ||
if (!p) | ||
goto out_unlock; | ||
retval = security_task_getscheduler(p); | ||
if (retval) | ||
goto out_unlock; | ||
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cpus_and(mask, p->thread.user_cpus_allowed, cpu_possible_map); | ||
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out_unlock: | ||
read_unlock(&tasklist_lock); | ||
unlock_cpu_hotplug(); | ||
if (retval) | ||
return retval; | ||
if (copy_to_user(user_mask_ptr, &mask, real_len)) | ||
return -EFAULT; | ||
return real_len; | ||
} | ||
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static int __init fpaff_thresh(char *str) | ||
{ | ||
get_option(&str, &fpaff_threshold); | ||
return 1; | ||
} | ||
__setup("fpaff=", fpaff_thresh); | ||
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/* | ||
* FPU Use Factor empirically derived from experiments on 34K | ||
*/ | ||
#define FPUSEFACTOR 333 | ||
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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); | ||
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return 0; | ||
} | ||
arch_initcall(mt_fp_affinity_init); |
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