forked from luck/tmp_suning_uos_patched
e302cf3f96
Impact: refactor the branch tracer This patch adapts the branch tracer to the tracing API. This is a proof of concept because the branch tracer implements two "stat tracing" that were split in two files. So I added an option to the branch tracer: stat_all_branch. If it is set, then trace_stat will output all of the branches entries stats. Otherwise, it will print the annotated branches. Its is a kind of quick trick, waiting for a better solution. By default, the annotated branches stat are sorted by incorrect branch prediction percentage. Ie: correct incorrect % Function File Line ------- --------- - -------- ---- ---- 0 1 100 native_smp_prepare_cpus smpboot.c 1228 0 1 100 hpet_rtc_timer_reinit hpet.c 1057 0 18032 100 sched_info_queued sched_stats.h 223 0 684 100 yield_task_fair sched_fair.c 984 0 282 100 pre_schedule_rt sched_rt.c 1263 0 13414 100 sched_info_dequeued sched_stats.h 178 0 21724 100 sched_info_switch sched_stats.h 270 0 1 100 get_signal_to_deliver signal.c 1820 0 8 100 __cancel_work_timer workqueue.c 560 0 212 100 verify_export_symbols module.c 1509 0 17 100 __rmqueue_fallback page_alloc.c 793 0 43 100 clear_page_mlock internal.h 129 0 124 100 try_to_unmap_anon rmap.c 1021 0 53 100 try_to_unmap_anon rmap.c 1013 0 6 100 vma_address rmap.c 232 0 3301 100 try_to_unmap_file rmap.c 1082 0 466 100 try_to_unmap_file rmap.c 1077 0 1 100 mem_cgroup_create memcontrol.c 1090 0 3 100 inotify_find_update_watch inotify.c 726 2 30163 99 perf_counter_task_sched_out perf_counter.c 385 1 2935 99 percpu_free allocpercpu.c 138 1544 297672 99 dentry_lru_del_init dcache.c 153 8 1074 99 input_pass_event input.c 86 1390 76781 98 mapping_unevictable pagemap.h 50 280 6665 95 pick_next_task_rt sched_rt.c 889 750 4826 86 next_pidmap pid.c 194 2 8 80 blocking_notifier_chain_regist notifier.c 220 36 130 78 ioremap_pte_range ioremap.c 22 1093 3247 74 IS_ERR err.h 34 1023 2908 73 sched_slice sched_fair.c 445 22 60 73 disk_put_part genhd.h 206 [...] It enables a developer to quickly address the source of incorrect branch predictions. Note that this sorting would be better with a second sort on the number of incorrect predictions. Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
412 lines
8.9 KiB
C
412 lines
8.9 KiB
C
/*
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* unlikely profiler
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*
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* Copyright (C) 2008 Steven Rostedt <srostedt@redhat.com>
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*/
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#include <linux/kallsyms.h>
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#include <linux/seq_file.h>
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#include <linux/spinlock.h>
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#include <linux/irqflags.h>
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#include <linux/debugfs.h>
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#include <linux/uaccess.h>
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#include <linux/module.h>
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#include <linux/ftrace.h>
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#include <linux/hash.h>
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#include <linux/fs.h>
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#include <asm/local.h>
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#include "trace.h"
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#include "trace_output.h"
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static struct tracer branch_trace;
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#ifdef CONFIG_BRANCH_TRACER
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static int branch_tracing_enabled __read_mostly;
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static DEFINE_MUTEX(branch_tracing_mutex);
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static struct trace_array *branch_tracer;
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static void
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probe_likely_condition(struct ftrace_branch_data *f, int val, int expect)
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{
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struct trace_array *tr = branch_tracer;
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struct ring_buffer_event *event;
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struct trace_branch *entry;
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unsigned long flags, irq_flags;
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int cpu, pc;
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const char *p;
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/*
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* I would love to save just the ftrace_likely_data pointer, but
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* this code can also be used by modules. Ugly things can happen
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* if the module is unloaded, and then we go and read the
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* pointer. This is slower, but much safer.
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*/
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if (unlikely(!tr))
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return;
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local_irq_save(flags);
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cpu = raw_smp_processor_id();
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if (atomic_inc_return(&tr->data[cpu]->disabled) != 1)
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goto out;
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event = ring_buffer_lock_reserve(tr->buffer, sizeof(*entry),
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&irq_flags);
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if (!event)
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goto out;
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pc = preempt_count();
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entry = ring_buffer_event_data(event);
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tracing_generic_entry_update(&entry->ent, flags, pc);
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entry->ent.type = TRACE_BRANCH;
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/* Strip off the path, only save the file */
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p = f->file + strlen(f->file);
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while (p >= f->file && *p != '/')
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p--;
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p++;
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strncpy(entry->func, f->func, TRACE_FUNC_SIZE);
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strncpy(entry->file, p, TRACE_FILE_SIZE);
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entry->func[TRACE_FUNC_SIZE] = 0;
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entry->file[TRACE_FILE_SIZE] = 0;
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entry->line = f->line;
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entry->correct = val == expect;
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ring_buffer_unlock_commit(tr->buffer, event, irq_flags);
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out:
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atomic_dec(&tr->data[cpu]->disabled);
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local_irq_restore(flags);
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}
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static inline
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void trace_likely_condition(struct ftrace_branch_data *f, int val, int expect)
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{
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if (!branch_tracing_enabled)
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return;
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probe_likely_condition(f, val, expect);
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}
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int enable_branch_tracing(struct trace_array *tr)
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{
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int ret = 0;
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mutex_lock(&branch_tracing_mutex);
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branch_tracer = tr;
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/*
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* Must be seen before enabling. The reader is a condition
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* where we do not need a matching rmb()
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*/
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smp_wmb();
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branch_tracing_enabled++;
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mutex_unlock(&branch_tracing_mutex);
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return ret;
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}
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void disable_branch_tracing(void)
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{
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mutex_lock(&branch_tracing_mutex);
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if (!branch_tracing_enabled)
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goto out_unlock;
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branch_tracing_enabled--;
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out_unlock:
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mutex_unlock(&branch_tracing_mutex);
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}
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static void start_branch_trace(struct trace_array *tr)
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{
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enable_branch_tracing(tr);
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}
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static void stop_branch_trace(struct trace_array *tr)
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{
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disable_branch_tracing();
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}
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static int branch_trace_init(struct trace_array *tr)
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{
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int cpu;
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for_each_online_cpu(cpu)
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tracing_reset(tr, cpu);
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start_branch_trace(tr);
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return 0;
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}
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static void branch_trace_reset(struct trace_array *tr)
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{
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stop_branch_trace(tr);
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}
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static int
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trace_print_print(struct trace_seq *s, struct trace_entry *entry, int flags)
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{
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struct print_entry *field;
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trace_assign_type(field, entry);
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if (seq_print_ip_sym(s, field->ip, flags))
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goto partial;
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if (trace_seq_printf(s, ": %s", field->buf))
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goto partial;
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partial:
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return TRACE_TYPE_PARTIAL_LINE;
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}
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static int
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trace_branch_print(struct trace_seq *s, struct trace_entry *entry, int flags)
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{
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struct trace_branch *field;
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trace_assign_type(field, entry);
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if (trace_seq_printf(s, "[%s] %s:%s:%d\n",
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field->correct ? " ok " : " MISS ",
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field->func,
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field->file,
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field->line))
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return TRACE_TYPE_PARTIAL_LINE;
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return 0;
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}
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static struct trace_event trace_branch_event = {
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.type = TRACE_BRANCH,
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.trace = trace_branch_print,
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.latency_trace = trace_branch_print,
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.raw = trace_nop_print,
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.hex = trace_nop_print,
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.binary = trace_nop_print,
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};
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#else
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static inline
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void trace_likely_condition(struct ftrace_branch_data *f, int val, int expect)
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{
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}
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#endif /* CONFIG_BRANCH_TRACER */
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void ftrace_likely_update(struct ftrace_branch_data *f, int val, int expect)
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{
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/*
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* I would love to have a trace point here instead, but the
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* trace point code is so inundated with unlikely and likely
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* conditions that the recursive nightmare that exists is too
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* much to try to get working. At least for now.
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*/
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trace_likely_condition(f, val, expect);
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/* FIXME: Make this atomic! */
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if (val == expect)
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f->correct++;
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else
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f->incorrect++;
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}
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EXPORT_SYMBOL(ftrace_likely_update);
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extern unsigned long __start_annotated_branch_profile[];
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extern unsigned long __stop_annotated_branch_profile[];
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static int annotated_branch_stat_headers(struct seq_file *m)
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{
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seq_printf(m, " correct incorrect %% ");
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seq_printf(m, " Function "
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" File Line\n"
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" ------- --------- - "
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" -------- "
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" ---- ----\n");
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return 0;
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}
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static inline long get_incorrect_percent(struct ftrace_branch_data *p)
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{
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long percent;
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if (p->correct) {
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percent = p->incorrect * 100;
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percent /= p->correct + p->incorrect;
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} else
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percent = p->incorrect ? 100 : -1;
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return percent;
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}
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static int branch_stat_show(struct seq_file *m, void *v)
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{
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struct ftrace_branch_data *p = v;
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const char *f;
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long percent;
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/* Only print the file, not the path */
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f = p->file + strlen(p->file);
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while (f >= p->file && *f != '/')
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f--;
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f++;
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/*
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* The miss is overlayed on correct, and hit on incorrect.
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*/
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percent = get_incorrect_percent(p);
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seq_printf(m, "%8lu %8lu ", p->correct, p->incorrect);
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if (percent < 0)
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seq_printf(m, " X ");
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else
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seq_printf(m, "%3ld ", percent);
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seq_printf(m, "%-30.30s %-20.20s %d\n", p->func, f, p->line);
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return 0;
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}
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static void *annotated_branch_stat_start(void)
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{
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return __start_annotated_branch_profile;
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}
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static void *
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annotated_branch_stat_next(void *v, int idx)
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{
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struct ftrace_branch_data *p = v;
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++p;
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if ((void *)p >= (void *)__stop_annotated_branch_profile)
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return NULL;
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return p;
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}
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static int annotated_branch_stat_cmp(void *p1, void *p2)
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{
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struct ftrace_branch_data *a = p1;
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struct ftrace_branch_data *b = p2;
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long percent_a, percent_b;
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percent_a = get_incorrect_percent(a);
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percent_b = get_incorrect_percent(b);
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if (percent_a < percent_b)
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return -1;
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if (percent_a > percent_b)
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return 1;
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else
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return 0;
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}
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#ifdef CONFIG_PROFILE_ALL_BRANCHES
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enum {
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TRACE_BRANCH_OPT_ALL = 0x1
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};
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static struct tracer_opt branch_opts[] = {
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{ TRACER_OPT(stat_all_branch, TRACE_BRANCH_OPT_ALL) },
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{ }
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};
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static struct tracer_flags branch_flags = {
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.val = 0,
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.opts = branch_opts
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};
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extern unsigned long __start_branch_profile[];
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extern unsigned long __stop_branch_profile[];
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static int all_branch_stat_headers(struct seq_file *m)
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{
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seq_printf(m, " miss hit %% ");
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seq_printf(m, " Function "
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" File Line\n"
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" ------- --------- - "
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" -------- "
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" ---- ----\n");
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return 0;
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}
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static void *all_branch_stat_start(void)
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{
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return __start_branch_profile;
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}
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static void *
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all_branch_stat_next(void *v, int idx)
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{
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struct ftrace_branch_data *p = v;
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++p;
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if ((void *)p >= (void *)__stop_branch_profile)
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return NULL;
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return p;
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}
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static int branch_set_flag(u32 old_flags, u32 bit, int set)
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{
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if (bit == TRACE_BRANCH_OPT_ALL) {
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if (set) {
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branch_trace.stat_headers = all_branch_stat_headers;
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branch_trace.stat_start = all_branch_stat_start;
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branch_trace.stat_next = all_branch_stat_next;
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branch_trace.stat_cmp = NULL;
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} else {
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branch_trace.stat_headers =
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annotated_branch_stat_headers;
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branch_trace.stat_start = annotated_branch_stat_start;
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branch_trace.stat_next = annotated_branch_stat_next;
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branch_trace.stat_cmp = annotated_branch_stat_cmp;
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}
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init_tracer_stat(&branch_trace);
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}
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return 0;
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}
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#endif /* CONFIG_PROFILE_ALL_BRANCHES */
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static struct tracer branch_trace __read_mostly =
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{
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.name = "branch",
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#ifdef CONFIG_BRANCH_TRACER
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.init = branch_trace_init,
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.reset = branch_trace_reset,
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#ifdef CONFIG_FTRACE_SELFTEST
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.selftest = trace_selftest_startup_branch,
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#endif /* CONFIG_FTRACE_SELFTEST */
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#endif /* CONFIG_BRANCH_TRACER */
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.stat_start = annotated_branch_stat_start,
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.stat_next = annotated_branch_stat_next,
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.stat_show = branch_stat_show,
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.stat_headers = annotated_branch_stat_headers,
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.stat_cmp = annotated_branch_stat_cmp,
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#ifdef CONFIG_PROFILE_ALL_BRANCHES
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.flags = &branch_flags,
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.set_flag = branch_set_flag,
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#endif
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};
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__init static int init_branch_trace(void)
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{
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#ifdef CONFIG_BRANCH_TRACER
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int ret;
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ret = register_ftrace_event(&trace_branch_event);
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if (!ret) {
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printk(KERN_WARNING "Warning: could not register branch events\n");
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return 1;
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}
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#endif
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return register_tracer(&branch_trace);
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}
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device_initcall(init_branch_trace);
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