diff options
Diffstat (limited to 'kernel/profile.c')
| -rw-r--r-- | kernel/profile.c | 563 |
1 files changed, 563 insertions, 0 deletions
diff --git a/kernel/profile.c b/kernel/profile.c new file mode 100644 index 000000000000..a38fa70075fe --- /dev/null +++ b/kernel/profile.c @@ -0,0 +1,563 @@ +/* + * 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/config.h> +#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 <asm/sections.h> +#include <asm/semaphore.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 *); + +static atomic_t *prof_buffer; +static unsigned long prof_len, prof_shift; +static int prof_on; +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 DECLARE_MUTEX(profile_flip_mutex); +#endif /* CONFIG_SMP */ + +static int __init profile_setup(char * str) +{ + int par; + + if (!strncmp(str, "schedule", 8)) { + prof_on = SCHED_PROFILING; + printk(KERN_INFO "kernel schedule profiling enabled\n"); + if (str[7] == ',') + str += 8; + } + 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 DECLARE_RWSEM(profile_rwsem); +static DEFINE_RWLOCK(handoff_lock); +static struct notifier_block * task_exit_notifier; +static struct notifier_block * task_free_notifier; +static struct notifier_block * munmap_notifier; + +void profile_task_exit(struct task_struct * task) +{ + down_read(&profile_rwsem); + notifier_call_chain(&task_exit_notifier, 0, task); + up_read(&profile_rwsem); +} + +int profile_handoff_task(struct task_struct * task) +{ + int ret; + read_lock(&handoff_lock); + ret = notifier_call_chain(&task_free_notifier, 0, task); + read_unlock(&handoff_lock); + return (ret == NOTIFY_OK) ? 1 : 0; +} + +void profile_munmap(unsigned long addr) +{ + down_read(&profile_rwsem); + notifier_call_chain(&munmap_notifier, 0, (void *)addr); + up_read(&profile_rwsem); +} + +int task_handoff_register(struct notifier_block * n) +{ + int err = -EINVAL; + + write_lock(&handoff_lock); + err = notifier_chain_register(&task_free_notifier, n); + write_unlock(&handoff_lock); + return err; +} + +int task_handoff_unregister(struct notifier_block * n) +{ + int err = -EINVAL; + + write_lock(&handoff_lock); + err = notifier_chain_unregister(&task_free_notifier, n); + write_unlock(&handoff_lock); + return err; +} + +int profile_event_register(enum profile_type type, struct notifier_block * n) +{ + int err = -EINVAL; + + down_write(&profile_rwsem); + + switch (type) { + case PROFILE_TASK_EXIT: + err = notifier_chain_register(&task_exit_notifier, n); + break; + case PROFILE_MUNMAP: + err = notifier_chain_register(&munmap_notifier, n); + break; + } + + up_write(&profile_rwsem); + + return err; +} + + +int profile_event_unregister(enum profile_type type, struct notifier_block * n) +{ + int err = -EINVAL; + + down_write(&profile_rwsem); + + switch (type) { + case PROFILE_TASK_EXIT: + err = notifier_chain_unregister(&task_exit_notifier, n); + break; + case PROFILE_MUNMAP: + err = notifier_chain_unregister(&munmap_notifier, n); + break; + } + + up_write(&profile_rwsem); + 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_kernel(); +} + +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; + + down(&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; + } + } + up(&profile_flip_mutex); +} + +static void profile_discard_flip_buffers(void) +{ + int i, cpu; + + down(&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)); + } + up(&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, 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, 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) +{ + 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(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, 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, 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; + 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 */ |