Ralf Baechle | 295cbf6 | 2007-07-03 14:37:43 +0100 | [diff] [blame] | 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; |
| 53 | |
| 54 | if (len < sizeof(new_mask)) |
| 55 | return -EINVAL; |
| 56 | |
| 57 | if (copy_from_user(&new_mask, user_mask_ptr, sizeof(new_mask))) |
| 58 | return -EFAULT; |
| 59 | |
| 60 | lock_cpu_hotplug(); |
| 61 | read_lock(&tasklist_lock); |
| 62 | |
| 63 | p = find_process_by_pid(pid); |
| 64 | if (!p) { |
| 65 | read_unlock(&tasklist_lock); |
| 66 | unlock_cpu_hotplug(); |
| 67 | return -ESRCH; |
| 68 | } |
| 69 | |
| 70 | /* |
| 71 | * It is not safe to call set_cpus_allowed with the |
| 72 | * tasklist_lock held. We will bump the task_struct's |
| 73 | * usage count and drop tasklist_lock before invoking |
| 74 | * set_cpus_allowed. |
| 75 | */ |
| 76 | get_task_struct(p); |
| 77 | |
| 78 | retval = -EPERM; |
| 79 | if ((current->euid != p->euid) && (current->euid != p->uid) && |
| 80 | !capable(CAP_SYS_NICE)) { |
| 81 | read_unlock(&tasklist_lock); |
| 82 | goto out_unlock; |
| 83 | } |
| 84 | |
| 85 | retval = security_task_setscheduler(p, 0, NULL); |
| 86 | if (retval) |
| 87 | goto out_unlock; |
| 88 | |
| 89 | /* Record new user-specified CPU set for future reference */ |
| 90 | p->thread.user_cpus_allowed = new_mask; |
| 91 | |
| 92 | /* Unlock the task list */ |
| 93 | read_unlock(&tasklist_lock); |
| 94 | |
| 95 | /* Compute new global allowed CPU set if necessary */ |
| 96 | if ((p->thread.mflags & MF_FPUBOUND) |
| 97 | && cpus_intersects(new_mask, mt_fpu_cpumask)) { |
| 98 | cpus_and(effective_mask, new_mask, mt_fpu_cpumask); |
| 99 | retval = set_cpus_allowed(p, effective_mask); |
| 100 | } else { |
| 101 | p->thread.mflags &= ~MF_FPUBOUND; |
| 102 | retval = set_cpus_allowed(p, new_mask); |
| 103 | } |
| 104 | |
| 105 | |
| 106 | out_unlock: |
| 107 | put_task_struct(p); |
| 108 | unlock_cpu_hotplug(); |
| 109 | return retval; |
| 110 | } |
| 111 | |
| 112 | /* |
| 113 | * mipsmt_sys_sched_getaffinity - get the cpu affinity of a process |
| 114 | */ |
| 115 | asmlinkage long mipsmt_sys_sched_getaffinity(pid_t pid, unsigned int len, |
| 116 | unsigned long __user *user_mask_ptr) |
| 117 | { |
| 118 | unsigned int real_len; |
| 119 | cpumask_t mask; |
| 120 | int retval; |
| 121 | struct task_struct *p; |
| 122 | |
| 123 | real_len = sizeof(mask); |
| 124 | if (len < real_len) |
| 125 | return -EINVAL; |
| 126 | |
| 127 | lock_cpu_hotplug(); |
| 128 | read_lock(&tasklist_lock); |
| 129 | |
| 130 | retval = -ESRCH; |
| 131 | p = find_process_by_pid(pid); |
| 132 | if (!p) |
| 133 | goto out_unlock; |
| 134 | retval = security_task_getscheduler(p); |
| 135 | if (retval) |
| 136 | goto out_unlock; |
| 137 | |
| 138 | cpus_and(mask, p->thread.user_cpus_allowed, cpu_possible_map); |
| 139 | |
| 140 | out_unlock: |
| 141 | read_unlock(&tasklist_lock); |
| 142 | unlock_cpu_hotplug(); |
| 143 | if (retval) |
| 144 | return retval; |
| 145 | if (copy_to_user(user_mask_ptr, &mask, real_len)) |
| 146 | return -EFAULT; |
| 147 | return real_len; |
| 148 | } |
| 149 | |
| 150 | |
| 151 | static int __init fpaff_thresh(char *str) |
| 152 | { |
| 153 | get_option(&str, &fpaff_threshold); |
| 154 | return 1; |
| 155 | } |
| 156 | __setup("fpaff=", fpaff_thresh); |
| 157 | |
| 158 | /* |
| 159 | * FPU Use Factor empirically derived from experiments on 34K |
| 160 | */ |
| 161 | #define FPUSEFACTOR 333 |
| 162 | |
| 163 | static __init int mt_fp_affinity_init(void) |
| 164 | { |
| 165 | if (fpaff_threshold >= 0) { |
| 166 | mt_fpemul_threshold = fpaff_threshold; |
| 167 | } else { |
| 168 | mt_fpemul_threshold = |
| 169 | (FPUSEFACTOR * (loops_per_jiffy/(500000/HZ))) / HZ; |
| 170 | } |
| 171 | printk(KERN_DEBUG "FPU Affinity set after %ld emulations\n", |
| 172 | mt_fpemul_threshold); |
| 173 | |
| 174 | return 0; |
| 175 | } |
| 176 | arch_initcall(mt_fp_affinity_init); |