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tracing: add "power-tracer": C/P state tracer to help power optimization
Impact: new "power-tracer" ftrace plugin This patch adds a C/P-state ftrace plugin that will generate detailed statistics about the C/P-states that are being used, so that we can look at detailed decisions that the C/P-state code is making, rather than the too high level "average" that we have today. An example way of using this is: mount -t debugfs none /sys/kernel/debug echo cstate > /sys/kernel/debug/tracing/current_tracer echo 1 > /sys/kernel/debug/tracing/tracing_enabled sleep 1 echo 0 > /sys/kernel/debug/tracing/tracing_enabled cat /sys/kernel/debug/tracing/trace | perl scripts/trace/cstate.pl > out.svg Signed-off-by: Arjan van de Ven <arjan@linux.intel.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
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Arjan van de Ven
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Ingo Molnar
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Nov 26, 2008
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,179 @@ | ||
| /* | ||
| * ring buffer based C-state tracer | ||
| * | ||
| * Arjan van de Ven <arjan@linux.intel.com> | ||
| * Copyright (C) 2008 Intel Corporation | ||
| * | ||
| * Much is borrowed from trace_boot.c which is | ||
| * Copyright (C) 2008 Frederic Weisbecker <fweisbec@gmail.com> | ||
| * | ||
| */ | ||
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| #include <linux/init.h> | ||
| #include <linux/debugfs.h> | ||
| #include <linux/ftrace.h> | ||
| #include <linux/kallsyms.h> | ||
| #include <linux/module.h> | ||
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| #include "trace.h" | ||
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| static struct trace_array *power_trace; | ||
| static int __read_mostly trace_power_enabled; | ||
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| static void start_power_trace(struct trace_array *tr) | ||
| { | ||
| trace_power_enabled = 1; | ||
| } | ||
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| static void stop_power_trace(struct trace_array *tr) | ||
| { | ||
| trace_power_enabled = 0; | ||
| } | ||
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| static int power_trace_init(struct trace_array *tr) | ||
| { | ||
| int cpu; | ||
| power_trace = tr; | ||
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| trace_power_enabled = 1; | ||
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| for_each_cpu_mask(cpu, cpu_possible_map) | ||
| tracing_reset(tr, cpu); | ||
| return 0; | ||
| } | ||
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| static enum print_line_t power_print_line(struct trace_iterator *iter) | ||
| { | ||
| int ret = 0; | ||
| struct trace_entry *entry = iter->ent; | ||
| struct trace_power *field ; | ||
| struct power_trace *it; | ||
| struct trace_seq *s = &iter->seq; | ||
| struct timespec stamp; | ||
| struct timespec duration; | ||
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| trace_assign_type(field, entry); | ||
| it = &field->state_data; | ||
| stamp = ktime_to_timespec(it->stamp); | ||
| duration = ktime_to_timespec(ktime_sub(it->end, it->stamp)); | ||
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| if (entry->type == TRACE_POWER) { | ||
| if (it->type == POWER_CSTATE) | ||
| ret = trace_seq_printf(s, "[%5ld.%09ld] CSTATE: Going to C%i on cpu %i for %ld.%09ld\n", | ||
| stamp.tv_sec, | ||
| stamp.tv_nsec, | ||
| it->state, iter->cpu, | ||
| duration.tv_sec, | ||
| duration.tv_nsec); | ||
| if (it->type == POWER_PSTATE) | ||
| ret = trace_seq_printf(s, "[%5ld.%09ld] PSTATE: Going to P%i on cpu %i\n", | ||
| stamp.tv_sec, | ||
| stamp.tv_nsec, | ||
| it->state, iter->cpu); | ||
| if (!ret) | ||
| return TRACE_TYPE_PARTIAL_LINE; | ||
| return TRACE_TYPE_HANDLED; | ||
| } | ||
| return TRACE_TYPE_UNHANDLED; | ||
| } | ||
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| static struct tracer power_tracer __read_mostly = | ||
| { | ||
| .name = "power", | ||
| .init = power_trace_init, | ||
| .start = start_power_trace, | ||
| .stop = stop_power_trace, | ||
| .reset = stop_power_trace, | ||
| .print_line = power_print_line, | ||
| }; | ||
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| static int init_power_trace(void) | ||
| { | ||
| return register_tracer(&power_tracer); | ||
| } | ||
| device_initcall(init_power_trace); | ||
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| void trace_power_start(struct power_trace *it, unsigned int type, | ||
| unsigned int level) | ||
| { | ||
| if (!trace_power_enabled) | ||
| return; | ||
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| memset(it, 0, sizeof(struct power_trace)); | ||
| it->state = level; | ||
| it->type = type; | ||
| it->stamp = ktime_get(); | ||
| } | ||
| EXPORT_SYMBOL_GPL(trace_power_start); | ||
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| void trace_power_end(struct power_trace *it) | ||
| { | ||
| struct ring_buffer_event *event; | ||
| struct trace_power *entry; | ||
| struct trace_array_cpu *data; | ||
| unsigned long irq_flags; | ||
| struct trace_array *tr = power_trace; | ||
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| if (!trace_power_enabled) | ||
| return; | ||
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| preempt_disable(); | ||
| it->end = ktime_get(); | ||
| data = tr->data[smp_processor_id()]; | ||
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| event = ring_buffer_lock_reserve(tr->buffer, sizeof(*entry), | ||
| &irq_flags); | ||
| if (!event) | ||
| goto out; | ||
| entry = ring_buffer_event_data(event); | ||
| tracing_generic_entry_update(&entry->ent, 0, 0); | ||
| entry->ent.type = TRACE_POWER; | ||
| entry->state_data = *it; | ||
| ring_buffer_unlock_commit(tr->buffer, event, irq_flags); | ||
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| trace_wake_up(); | ||
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| out: | ||
| preempt_enable(); | ||
| } | ||
| EXPORT_SYMBOL_GPL(trace_power_end); | ||
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| void trace_power_mark(struct power_trace *it, unsigned int type, | ||
| unsigned int level) | ||
| { | ||
| struct ring_buffer_event *event; | ||
| struct trace_power *entry; | ||
| struct trace_array_cpu *data; | ||
| unsigned long irq_flags; | ||
| struct trace_array *tr = power_trace; | ||
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| if (!trace_power_enabled) | ||
| return; | ||
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| memset(it, 0, sizeof(struct power_trace)); | ||
| it->state = level; | ||
| it->type = type; | ||
| it->stamp = ktime_get(); | ||
| preempt_disable(); | ||
| it->end = it->stamp; | ||
| data = tr->data[smp_processor_id()]; | ||
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| event = ring_buffer_lock_reserve(tr->buffer, sizeof(*entry), | ||
| &irq_flags); | ||
| if (!event) | ||
| goto out; | ||
| entry = ring_buffer_event_data(event); | ||
| tracing_generic_entry_update(&entry->ent, 0, 0); | ||
| entry->ent.type = TRACE_POWER; | ||
| entry->state_data = *it; | ||
| ring_buffer_unlock_commit(tr->buffer, event, irq_flags); | ||
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| trace_wake_up(); | ||
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| out: | ||
| preempt_enable(); | ||
| } | ||
| EXPORT_SYMBOL_GPL(trace_power_mark); |
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