/* * linux/kernel/profile.c * Simple profiling. Manages a direct-mapped profile hit count buffer, * with configurable resolution, support for restricting the cpus on * which profiling is done, and switching between cpu time and * schedule() calls via kernel command line parameters passed at boot. * * Scheduler profiling support, Arjan van de Ven and Ingo Molnar, * Red Hat, July 2004 * Consolidation of architecture support code for profiling, * William Irwin, Oracle, July 2004 * Amortized hit count accounting via per-cpu open-addressed hashtables * to resolve timer interrupt livelocks, William Irwin, Oracle, 2004 */ #include <linux/module.h> #include <linux/profile.h> #include <linux/bootmem.h> #include <linux/notifier.h> #include <linux/mm.h> #include <linux/cpumask.h> #include <linux/cpu.h> #include <linux/profile.h> #include <linux/highmem.h> #include <linux/mutex.h> #include <asm/sections.h> #include <asm/semaphore.h> #include <asm/irq_regs.h> struct profile_hit { u32 pc, hits; }; #define PROFILE_GRPSHIFT 3 #define PROFILE_GRPSZ (1 << PROFILE_GRPSHIFT) #define NR_PROFILE_HIT (PAGE_SIZE/sizeof(struct profile_hit)) #define NR_PROFILE_GRP (NR_PROFILE_HIT/PROFILE_GRPSZ) /* Oprofile timer tick hook */ int (*timer_hook)(struct pt_regs *) __read_mostly; static atomic_t *prof_buffer; static unsigned long prof_len, prof_shift; static int prof_on __read_mostly; static cpumask_t prof_cpu_mask = CPU_MASK_ALL; #ifdef CONFIG_SMP static DEFINE_PER_CPU(struct profile_hit *[2], cpu_profile_hits); static DEFINE_PER_CPU(int, cpu_profile_flip); static DEFINE_MUTEX(profile_flip_mutex); #endif /* CONFIG_SMP */ static int __init profile_setup(char * str) { static char __initdata schedstr[] = "schedule"; int par; if (!strncmp(str, schedstr, strlen(schedstr))) { prof_on = SCHED_PROFILING; if (str[strlen(schedstr)] == ',') str += strlen(schedstr) + 1; if (get_option(&str, &par)) prof_shift = par; printk(KERN_INFO "kernel schedule profiling enabled (shift: %ld)\n", prof_shift); } else if (get_option(&str, &par)) { prof_shift = par; prof_on = CPU_PROFILING; printk(KERN_INFO "kernel profiling enabled (shift: %ld)\n", prof_shift); } return 1; } __setup("profile=", profile_setup); void __init profile_init(void) { if (!prof_on) return; /* only text is profiled */ prof_len = (_etext - _stext) >> prof_shift; prof_buffer = alloc_bootmem(prof_len*sizeof(atomic_t)); } /* Profile event notifications */ #ifdef CONFIG_PROFILING static BLOCKING_NOTIFIER_HEAD(task_exit_notifier); static ATOMIC_NOTIFIER_HEAD(task_free_notifier); static BLOCKING_NOTIFIER_HEAD(munmap_notifier); void profile_task_exit(struct task_struct * task) { blocking_notifier_call_chain(&task_exit_notifier, 0, task); } int profile_handoff_task(struct task_struct * task) { int ret; ret = atomic_notifier_call_chain(&task_free_notifier, 0, task); return (ret == NOTIFY_OK) ? 1 : 0; } void profile_munmap(unsigned long addr) { blocking_notifier_call_chain(&munmap_notifier, 0, (void *)addr); } int task_handoff_register(struct notifier_block * n) { return atomic_notifier_chain_register(&task_free_notifier, n); } int task_handoff_unregister(struct notifier_block * n) { return atomic_notifier_chain_unregister(&task_free_notifier, n); } int profile_event_register(enum profile_type type, struct notifier_block * n) { int err = -EINVAL; switch (type) { case PROFILE_TASK_EXIT: err = blocking_notifier_chain_register( &task_exit_notifier, n); break; case PROFILE_MUNMAP: err = blocking_notifier_chain_register( &munmap_notifier, n); break; } return err; } int profile_event_unregister(enum profile_type type, struct notifier_block * n) { int err = -EINVAL; switch (type) { case PROFILE_TASK_EXIT: err = blocking_notifier_chain_unregister( &task_exit_notifier, n); break; case PROFILE_MUNMAP: err = blocking_notifier_chain_unregister( &munmap_notifier, n); break; } return err; } int register_timer_hook(int (*hook)(struct pt_regs *)) { if (timer_hook) return -EBUSY; timer_hook = hook; return 0; } void unregister_timer_hook(int (*hook)(struct pt_regs *)) { WARN_ON(hook != timer_hook); timer_hook = NULL; /* make sure all CPUs see the NULL hook */ synchronize_sched(); /* Allow ongoing interrupts to complete. */ } EXPORT_SYMBOL_GPL(register_timer_hook); EXPORT_SYMBOL_GPL(unregister_timer_hook); EXPORT_SYMBOL_GPL(task_handoff_register); EXPORT_SYMBOL_GPL(task_handoff_unregister); #endif /* CONFIG_PROFILING */ EXPORT_SYMBOL_GPL(profile_event_register); EXPORT_SYMBOL_GPL(profile_event_unregister); #ifdef CONFIG_SMP /* * Each cpu has a pair of open-addressed hashtables for pending * profile hits. read_profile() IPI's all cpus to request them * to flip buffers and flushes their contents to prof_buffer itself. * Flip requests are serialized by the profile_flip_mutex. The sole * use of having a second hashtable is for avoiding cacheline * contention that would otherwise happen during flushes of pending * profile hits required for the accuracy of reported profile hits * and so resurrect the interrupt livelock issue. * * The open-addressed hashtables are indexed by profile buffer slot * and hold the number of pending hits to that profile buffer slot on * a cpu in an entry. When the hashtable overflows, all pending hits * are accounted to their corresponding profile buffer slots with * atomic_add() and the hashtable emptied. As numerous pending hits * may be accounted to a profile buffer slot in a hashtable entry, * this amortizes a number of atomic profile buffer increments likely * to be far larger than the number of entries in the hashtable, * particularly given that the number of distinct profile buffer * positions to which hits are accounted during short intervals (e.g. * several seconds) is usually very small. Exclusion from buffer * flipping is provided by interrupt disablement (note that for * SCHED_PROFILING profile_hit() may be called from process context). * The hash function is meant to be lightweight as opposed to strong, * and was vaguely inspired by ppc64 firmware-supported inverted * pagetable hash functions, but uses a full hashtable full of finite * collision chains, not just pairs of them. * * -- wli */ static void __profile_flip_buffers(void *unused) { int cpu = smp_processor_id(); per_cpu(cpu_profile_flip, cpu) = !per_cpu(cpu_profile_flip, cpu); } static void profile_flip_buffers(void) { int i, j, cpu; mutex_lock(&profile_flip_mutex); j = per_cpu(cpu_profile_flip, get_cpu()); put_cpu(); on_each_cpu(__profile_flip_buffers, NULL, 0, 1); for_each_online_cpu(cpu) { struct profile_hit *hits = per_cpu(cpu_profile_hits, cpu)[j]; for (i = 0; i < NR_PROFILE_HIT; ++i) { if (!hits[i].hits) { if (hits[i].pc) hits[i].pc = 0; continue; } atomic_add(hits[i].hits, &prof_buffer[hits[i].pc]); hits[i].hits = hits[i].pc = 0; } } mutex_unlock(&profile_flip_mutex); } static void profile_discard_flip_buffers(void) { int i, cpu; mutex_lock(&profile_flip_mutex); i = per_cpu(cpu_profile_flip, get_cpu()); put_cpu(); on_each_cpu(__profile_flip_buffers, NULL, 0, 1); for_each_online_cpu(cpu) { struct profile_hit *hits = per_cpu(cpu_profile_hits, cpu)[i]; memset(hits, 0, NR_PROFILE_HIT*sizeof(struct profile_hit)); } mutex_unlock(&profile_flip_mutex); } void profile_hit(int type, void *__pc) { unsigned long primary, secondary, flags, pc = (unsigned long)__pc; int i, j, cpu; struct profile_hit *hits; if (prof_on != type || !prof_buffer) return; pc = min((pc - (unsigned long)_stext) >> prof_shift, prof_len - 1); i = primary = (pc & (NR_PROFILE_GRP - 1)) << PROFILE_GRPSHIFT; secondary = (~(pc << 1) & (NR_PROFILE_GRP - 1)) << PROFILE_GRPSHIFT; cpu = get_cpu(); hits = per_cpu(cpu_profile_hits, cpu)[per_cpu(cpu_profile_flip, cpu)]; if (!hits) { put_cpu(); return; } local_irq_save(flags); do { for (j = 0; j < PROFILE_GRPSZ; ++j) { if (hits[i + j].pc == pc) { hits[i + j].hits++; goto out; } else if (!hits[i + j].hits) { hits[i + j].pc = pc; hits[i + j].hits = 1; goto out; } } i = (i + secondary) & (NR_PROFILE_HIT - 1); } while (i != primary); atomic_inc(&prof_buffer[pc]); for (i = 0; i < NR_PROFILE_HIT; ++i) { atomic_add(hits[i].hits, &prof_buffer[hits[i].pc]); hits[i].pc = hits[i].hits = 0; } out: local_irq_restore(flags); put_cpu(); } #ifdef CONFIG_HOTPLUG_CPU static int __devinit profile_cpu_callback(struct notifier_block *info, unsigned long action, void *__cpu) { int node, cpu = (unsigned long)__cpu; struct page *page; switch (action) { case CPU_UP_PREPARE: node = cpu_to_node(cpu); per_cpu(cpu_profile_flip, cpu) = 0; if (!per_cpu(cpu_profile_hits, cpu)[1]) { page = alloc_pages_node(node, GFP_KERNEL | __GFP_ZERO | GFP_THISNODE, 0); if (!page) return NOTIFY_BAD; per_cpu(cpu_profile_hits, cpu)[1] = page_address(page); } if (!per_cpu(cpu_profile_hits, cpu)[0]) { page = alloc_pages_node(node, GFP_KERNEL | __GFP_ZERO | GFP_THISNODE, 0); if (!page) goto out_free; per_cpu(cpu_profile_hits, cpu)[0] = page_address(page); } break; out_free: page = virt_to_page(per_cpu(cpu_profile_hits, cpu)[1]); per_cpu(cpu_profile_hits, cpu)[1] = NULL; __free_page(page); return NOTIFY_BAD; case CPU_ONLINE: cpu_set(cpu, prof_cpu_mask); break; case CPU_UP_CANCELED: case CPU_DEAD: cpu_clear(cpu, prof_cpu_mask); if (per_cpu(cpu_profile_hits, cpu)[0]) { page = virt_to_page(per_cpu(cpu_profile_hits, cpu)[0]); per_cpu(cpu_profile_hits, cpu)[0] = NULL; __free_page(page); } if (per_cpu(cpu_profile_hits, cpu)[1]) { page = virt_to_page(per_cpu(cpu_profile_hits, cpu)[1]); per_cpu(cpu_profile_hits, cpu)[1] = NULL; __free_page(page); } break; } return NOTIFY_OK; } #endif /* CONFIG_HOTPLUG_CPU */ #else /* !CONFIG_SMP */ #define profile_flip_buffers() do { } while (0) #define profile_discard_flip_buffers() do { } while (0) void profile_hit(int type, void *__pc) { unsigned long pc; if (prof_on != type || !prof_buffer) return; pc = ((unsigned long)__pc - (unsigned long)_stext) >> prof_shift; atomic_inc(&prof_buffer[min(pc, prof_len - 1)]); } #endif /* !CONFIG_SMP */ void profile_tick(int type) { struct pt_regs *regs = get_irq_regs(); if (type == CPU_PROFILING && timer_hook) timer_hook(regs); if (!user_mode(regs) && cpu_isset(smp_processor_id(), prof_cpu_mask)) profile_hit(type, (void *)profile_pc(regs)); } #ifdef CONFIG_PROC_FS #include <linux/proc_fs.h> #include <asm/uaccess.h> #include <asm/ptrace.h> static int prof_cpu_mask_read_proc (char *page, char **start, off_t off, int count, int *eof, void *data) { int len = cpumask_scnprintf(page, count, *(cpumask_t *)data); if (count - len < 2) return -EINVAL; len += sprintf(page + len, "\n"); return len; } static int prof_cpu_mask_write_proc (struct file *file, const char __user *buffer, unsigned long count, void *data) { cpumask_t *mask = (cpumask_t *)data; unsigned long full_count = count, err; cpumask_t new_value; err = cpumask_parse_user(buffer, count, new_value); if (err) return err; *mask = new_value; return full_count; } void create_prof_cpu_mask(struct proc_dir_entry *root_irq_dir) { struct proc_dir_entry *entry; /* create /proc/irq/prof_cpu_mask */ if (!(entry = create_proc_entry("prof_cpu_mask", 0600, root_irq_dir))) return; entry->nlink = 1; entry->data = (void *)&prof_cpu_mask; entry->read_proc = prof_cpu_mask_read_proc; entry->write_proc = prof_cpu_mask_write_proc; } /* * This function accesses profiling information. The returned data is * binary: the sampling step and the actual contents of the profile * buffer. Use of the program readprofile is recommended in order to * get meaningful info out of these data. */ static ssize_t read_profile(struct file *file, char __user *buf, size_t count, loff_t *ppos) { unsigned long p = *ppos; ssize_t read; char * pnt; unsigned int sample_step = 1 << prof_shift; profile_flip_buffers(); if (p >= (prof_len+1)*sizeof(unsigned int)) return 0; if (count > (prof_len+1)*sizeof(unsigned int) - p) count = (prof_len+1)*sizeof(unsigned int) - p; read = 0; while (p < sizeof(unsigned int) && count > 0) { put_user(*((char *)(&sample_step)+p),buf); buf++; p++; count--; read++; } pnt = (char *)prof_buffer + p - sizeof(atomic_t); if (copy_to_user(buf,(void *)pnt,count)) return -EFAULT; read += count; *ppos += read; return read; } /* * Writing to /proc/profile resets the counters * * Writing a 'profiling multiplier' value into it also re-sets the profiling * interrupt frequency, on architectures that support this. */ static ssize_t write_profile(struct file *file, const char __user *buf, size_t count, loff_t *ppos) { #ifdef CONFIG_SMP extern int setup_profiling_timer (unsigned int multiplier); if (count == sizeof(int)) { unsigned int multiplier; if (copy_from_user(&multiplier, buf, sizeof(int))) return -EFAULT; if (setup_profiling_timer(multiplier)) return -EINVAL; } #endif profile_discard_flip_buffers(); memset(prof_buffer, 0, prof_len * sizeof(atomic_t)); return count; } static struct file_operations proc_profile_operations = { .read = read_profile, .write = write_profile, }; #ifdef CONFIG_SMP static void __init profile_nop(void *unused) { } static int __init create_hash_tables(void) { int cpu; for_each_online_cpu(cpu) { int node = cpu_to_node(cpu); struct page *page; page = alloc_pages_node(node, GFP_KERNEL | __GFP_ZERO | GFP_THISNODE, 0); if (!page) goto out_cleanup; per_cpu(cpu_profile_hits, cpu)[1] = (struct profile_hit *)page_address(page); page = alloc_pages_node(node, GFP_KERNEL | __GFP_ZERO | GFP_THISNODE, 0); if (!page) goto out_cleanup; per_cpu(cpu_profile_hits, cpu)[0] = (struct profile_hit *)page_address(page); } return 0; out_cleanup: prof_on = 0; smp_mb(); on_each_cpu(profile_nop, NULL, 0, 1); for_each_online_cpu(cpu) { struct page *page; if (per_cpu(cpu_profile_hits, cpu)[0]) { page = virt_to_page(per_cpu(cpu_profile_hits, cpu)[0]); per_cpu(cpu_profile_hits, cpu)[0] = NULL; __free_page(page); } if (per_cpu(cpu_profile_hits, cpu)[1]) { page = virt_to_page(per_cpu(cpu_profile_hits, cpu)[1]); per_cpu(cpu_profile_hits, cpu)[1] = NULL; __free_page(page); } } return -1; } #else #define create_hash_tables() ({ 0; }) #endif static int __init create_proc_profile(void) { struct proc_dir_entry *entry; if (!prof_on) return 0; if (create_hash_tables()) return -1; if (!(entry = create_proc_entry("profile", S_IWUSR | S_IRUGO, NULL))) return 0; entry->proc_fops = &proc_profile_operations; entry->size = (1+prof_len) * sizeof(atomic_t); hotcpu_notifier(profile_cpu_callback, 0); return 0; } module_init(create_proc_profile); #endif /* CONFIG_PROC_FS */