diff options
Diffstat (limited to 'arch/mips/kernel/mips-mt-fpaff.c')
| -rw-r--r-- | arch/mips/kernel/mips-mt-fpaff.c | 176 |
1 files changed, 176 insertions, 0 deletions
diff --git a/arch/mips/kernel/mips-mt-fpaff.c b/arch/mips/kernel/mips-mt-fpaff.c new file mode 100644 index 00000000000..ede5d73d652 --- /dev/null +++ b/arch/mips/kernel/mips-mt-fpaff.c @@ -0,0 +1,176 @@ +/* + * 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; + + if (len < sizeof(new_mask)) + return -EINVAL; + + if (copy_from_user(&new_mask, user_mask_ptr, sizeof(new_mask))) + return -EFAULT; + + lock_cpu_hotplug(); + read_lock(&tasklist_lock); + + p = find_process_by_pid(pid); + if (!p) { + read_unlock(&tasklist_lock); + unlock_cpu_hotplug(); + 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 */ + 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); + } + + +out_unlock: + put_task_struct(p); + unlock_cpu_hotplug(); + 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; + + lock_cpu_hotplug(); + 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); + unlock_cpu_hotplug(); + 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); |