--- /dev/null
+/*
+ * 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,
+ * Nadia Yvette Chambers, Oracle, July 2004
+ * Amortized hit count accounting via per-cpu open-addressed hashtables
+ * to resolve timer interrupt livelocks, Nadia Yvette Chambers,
+ * Oracle, 2004
+ */
+
+#include <linux/export.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/highmem.h>
+#include <linux/mutex.h>
+#include <linux/slab.h>
+#include <linux/vmalloc.h>
+#include <asm/sections.h>
+#include <asm/irq_regs.h>
+#include <asm/ptrace.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)
+
+static atomic_t *prof_buffer;
+static unsigned long prof_len, prof_shift;
+
+int prof_on __read_mostly;
+EXPORT_SYMBOL_GPL(prof_on);
+
+static cpumask_var_t prof_cpu_mask;
+#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 */
+
+int profile_setup(char *str)
+{
+ static const char schedstr[] = "schedule";
+ static const char sleepstr[] = "sleep";
+ static const char kvmstr[] = "kvm";
+ int par;
+
+ if (!strncmp(str, sleepstr, strlen(sleepstr))) {
+#ifdef CONFIG_SCHEDSTATS
+ prof_on = SLEEP_PROFILING;
+ if (str[strlen(sleepstr)] == ',')
+ str += strlen(sleepstr) + 1;
+ if (get_option(&str, &par))
+ prof_shift = par;
+ pr_info("kernel sleep profiling enabled (shift: %ld)\n",
+ prof_shift);
+#else
+ pr_warn("kernel sleep profiling requires CONFIG_SCHEDSTATS\n");
+#endif /* CONFIG_SCHEDSTATS */
+ } else 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;
+ pr_info("kernel schedule profiling enabled (shift: %ld)\n",
+ prof_shift);
+ } else if (!strncmp(str, kvmstr, strlen(kvmstr))) {
+ prof_on = KVM_PROFILING;
+ if (str[strlen(kvmstr)] == ',')
+ str += strlen(kvmstr) + 1;
+ if (get_option(&str, &par))
+ prof_shift = par;
+ pr_info("kernel KVM profiling enabled (shift: %ld)\n",
+ prof_shift);
+ } else if (get_option(&str, &par)) {
+ prof_shift = par;
+ prof_on = CPU_PROFILING;
+ pr_info("kernel profiling enabled (shift: %ld)\n",
+ prof_shift);
+ }
+ return 1;
+}
+__setup("profile=", profile_setup);
+
+
+int __ref profile_init(void)
+{
+ int buffer_bytes;
+ if (!prof_on)
+ return 0;
+
+ /* only text is profiled */
+ prof_len = (_etext - _stext) >> prof_shift;
+ buffer_bytes = prof_len*sizeof(atomic_t);
+
+ if (!alloc_cpumask_var(&prof_cpu_mask, GFP_KERNEL))
+ return -ENOMEM;
+
+ cpumask_copy(prof_cpu_mask, cpu_possible_mask);
+
+ prof_buffer = kzalloc(buffer_bytes, GFP_KERNEL|__GFP_NOWARN);
+ if (prof_buffer)
+ return 0;
+
+ prof_buffer = alloc_pages_exact(buffer_bytes,
+ GFP_KERNEL|__GFP_ZERO|__GFP_NOWARN);
+ if (prof_buffer)
+ return 0;
+
+ prof_buffer = vzalloc(buffer_bytes);
+ if (prof_buffer)
+ return 0;
+
+ free_cpumask_var(prof_cpu_mask);
+ return -ENOMEM;
+}
+
+/* Profile event notifications */
+
+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);
+}
+EXPORT_SYMBOL_GPL(task_handoff_register);
+
+int task_handoff_unregister(struct notifier_block *n)
+{
+ return atomic_notifier_chain_unregister(&task_free_notifier, n);
+}
+EXPORT_SYMBOL_GPL(task_handoff_unregister);
+
+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;
+}
+EXPORT_SYMBOL_GPL(profile_event_register);
+
+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;
+}
+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 or SLEEP_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.
+ *
+ * -- nyc
+ */
+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, 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, 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);
+}
+
+static void do_profile_hits(int type, void *__pc, unsigned int nr_hits)
+{
+ unsigned long primary, secondary, flags, pc = (unsigned long)__pc;
+ int i, j, cpu;
+ struct profile_hit *hits;
+
+ 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;
+ }
+ /*
+ * We buffer the global profiler buffer into a per-CPU
+ * queue and thus reduce the number of global (and possibly
+ * NUMA-alien) accesses. The write-queue is self-coalescing:
+ */
+ local_irq_save(flags);
+ do {
+ for (j = 0; j < PROFILE_GRPSZ; ++j) {
+ if (hits[i + j].pc == pc) {
+ hits[i + j].hits += nr_hits;
+ goto out;
+ } else if (!hits[i + j].hits) {
+ hits[i + j].pc = pc;
+ hits[i + j].hits = nr_hits;
+ goto out;
+ }
+ }
+ i = (i + secondary) & (NR_PROFILE_HIT - 1);
+ } while (i != primary);
+
+ /*
+ * Add the current hit(s) and flush the write-queue out
+ * to the global buffer:
+ */
+ atomic_add(nr_hits, &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();
+}
+
+static int 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:
+ case CPU_UP_PREPARE_FROZEN:
+ node = cpu_to_mem(cpu);
+ per_cpu(cpu_profile_flip, cpu) = 0;
+ if (!per_cpu(cpu_profile_hits, cpu)[1]) {
+ page = alloc_pages_exact_node(node,
+ GFP_KERNEL | __GFP_ZERO,
+ 0);
+ if (!page)
+ return notifier_from_errno(-ENOMEM);
+ per_cpu(cpu_profile_hits, cpu)[1] = page_address(page);
+ }
+ if (!per_cpu(cpu_profile_hits, cpu)[0]) {
+ page = alloc_pages_exact_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 notifier_from_errno(-ENOMEM);
+ case CPU_ONLINE:
+ case CPU_ONLINE_FROZEN:
+ if (prof_cpu_mask != NULL)
+ cpumask_set_cpu(cpu, prof_cpu_mask);
+ break;
+ case CPU_UP_CANCELED:
+ case CPU_UP_CANCELED_FROZEN:
+ case CPU_DEAD:
+ case CPU_DEAD_FROZEN:
+ if (prof_cpu_mask != NULL)
+ cpumask_clear_cpu(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;
+}
+#else /* !CONFIG_SMP */
+#define profile_flip_buffers() do { } while (0)
+#define profile_discard_flip_buffers() do { } while (0)
+#define profile_cpu_callback NULL
+
+static void do_profile_hits(int type, void *__pc, unsigned int nr_hits)
+{
+ unsigned long pc;
+ pc = ((unsigned long)__pc - (unsigned long)_stext) >> prof_shift;
+ atomic_add(nr_hits, &prof_buffer[min(pc, prof_len - 1)]);
+}
+#endif /* !CONFIG_SMP */
+
+void profile_hits(int type, void *__pc, unsigned int nr_hits)
+{
+ if (prof_on != type || !prof_buffer)
+ return;
+ do_profile_hits(type, __pc, nr_hits);
+}
+EXPORT_SYMBOL_GPL(profile_hits);
+
+void profile_tick(int type)
+{
+ struct pt_regs *regs = get_irq_regs();
+
+ if (!user_mode(regs) && prof_cpu_mask != NULL &&
+ cpumask_test_cpu(smp_processor_id(), prof_cpu_mask))
+ profile_hit(type, (void *)profile_pc(regs));
+}
+
+#ifdef CONFIG_PROC_FS
+#include <linux/proc_fs.h>
+#include <linux/seq_file.h>
+#include <asm/uaccess.h>
+
+static int prof_cpu_mask_proc_show(struct seq_file *m, void *v)
+{
+ seq_printf(m, "%*pb\n", cpumask_pr_args(prof_cpu_mask));
+ return 0;
+}
+
+static int prof_cpu_mask_proc_open(struct inode *inode, struct file *file)
+{
+ return single_open(file, prof_cpu_mask_proc_show, NULL);
+}
+
+static ssize_t prof_cpu_mask_proc_write(struct file *file,
+ const char __user *buffer, size_t count, loff_t *pos)
+{
+ cpumask_var_t new_value;
+ int err;
+
+ if (!alloc_cpumask_var(&new_value, GFP_KERNEL))
+ return -ENOMEM;
+
+ err = cpumask_parse_user(buffer, count, new_value);
+ if (!err) {
+ cpumask_copy(prof_cpu_mask, new_value);
+ err = count;
+ }
+ free_cpumask_var(new_value);
+ return err;
+}
+
+static const struct file_operations prof_cpu_mask_proc_fops = {
+ .open = prof_cpu_mask_proc_open,
+ .read = seq_read,
+ .llseek = seq_lseek,
+ .release = single_release,
+ .write = prof_cpu_mask_proc_write,
+};
+
+void create_prof_cpu_mask(void)
+{
+ /* create /proc/irq/prof_cpu_mask */
+ proc_create("irq/prof_cpu_mask", 0600, NULL, &prof_cpu_mask_proc_fops);
+}
+
+/*
+ * 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) {
+ if (put_user(*((char *)(&sample_step)+p), buf))
+ return -EFAULT;
+ 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 const struct file_operations proc_profile_operations = {
+ .read = read_profile,
+ .write = write_profile,
+ .llseek = default_llseek,
+};
+
+#ifdef CONFIG_SMP
+static void profile_nop(void *unused)
+{
+}
+
+static int create_hash_tables(void)
+{
+ int cpu;
+
+ for_each_online_cpu(cpu) {
+ int node = cpu_to_mem(cpu);
+ struct page *page;
+
+ page = alloc_pages_exact_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_exact_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, 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
+
+int __ref create_proc_profile(void) /* false positive from hotcpu_notifier */
+{
+ struct proc_dir_entry *entry;
+ int err = 0;
+
+ if (!prof_on)
+ return 0;
+
+ cpu_notifier_register_begin();
+
+ if (create_hash_tables()) {
+ err = -ENOMEM;
+ goto out;
+ }
+
+ entry = proc_create("profile", S_IWUSR | S_IRUGO,
+ NULL, &proc_profile_operations);
+ if (!entry)
+ goto out;
+ proc_set_size(entry, (1 + prof_len) * sizeof(atomic_t));
+ __hotcpu_notifier(profile_cpu_callback, 0);
+
+out:
+ cpu_notifier_register_done();
+ return err;
+}
+subsys_initcall(create_proc_profile);
+#endif /* CONFIG_PROC_FS */
Code Review / kvmfornfv.git / blobdiff