]> www.pilppa.org Git - linux-2.6-omap-h63xx.git/blobdiff - kernel/trace/trace_functions_graph.c
Merge branch 'x86/core' into tracing/ftrace
[linux-2.6-omap-h63xx.git] / kernel / trace / trace_functions_graph.c
index 930c08e5b38e0d35ab93b79896b0150907d31e50..35257be6a9d6fb2a3352995d78a0e95abee65e94 100644 (file)
@@ -1,7 +1,7 @@
 /*
  *
  * Function graph tracer.
- * Copyright (c) 2008 Frederic Weisbecker <fweisbec@gmail.com>
+ * Copyright (c) 2008-2009 Frederic Weisbecker <fweisbec@gmail.com>
  * Mostly borrowed from function tracer which
  * is Copyright (c) Steven Rostedt <srostedt@redhat.com>
  *
@@ -12,6 +12,7 @@
 #include <linux/fs.h>
 
 #include "trace.h"
+#include "trace_output.h"
 
 #define TRACE_GRAPH_INDENT     2
 
 #define TRACE_GRAPH_PRINT_CPU          0x2
 #define TRACE_GRAPH_PRINT_OVERHEAD     0x4
 #define TRACE_GRAPH_PRINT_PROC         0x8
+#define TRACE_GRAPH_PRINT_DURATION     0x10
+#define TRACE_GRAPH_PRINT_ABS_TIME     0X20
 
 static struct tracer_opt trace_opts[] = {
-       /* Display overruns ? */
+       /* Display overruns? (for self-debug purpose) */
        { TRACER_OPT(funcgraph-overrun, TRACE_GRAPH_PRINT_OVERRUN) },
        /* Display CPU ? */
        { TRACER_OPT(funcgraph-cpu, TRACE_GRAPH_PRINT_CPU) },
@@ -30,26 +33,101 @@ static struct tracer_opt trace_opts[] = {
        { TRACER_OPT(funcgraph-overhead, TRACE_GRAPH_PRINT_OVERHEAD) },
        /* Display proc name/pid */
        { TRACER_OPT(funcgraph-proc, TRACE_GRAPH_PRINT_PROC) },
+       /* Display duration of execution */
+       { TRACER_OPT(funcgraph-duration, TRACE_GRAPH_PRINT_DURATION) },
+       /* Display absolute time of an entry */
+       { TRACER_OPT(funcgraph-abstime, TRACE_GRAPH_PRINT_ABS_TIME) },
        { } /* Empty entry */
 };
 
 static struct tracer_flags tracer_flags = {
        /* Don't display overruns and proc by default */
-       .val = TRACE_GRAPH_PRINT_CPU | TRACE_GRAPH_PRINT_OVERHEAD,
+       .val = TRACE_GRAPH_PRINT_CPU | TRACE_GRAPH_PRINT_OVERHEAD |
+              TRACE_GRAPH_PRINT_DURATION,
        .opts = trace_opts
 };
 
 /* pid on the last trace processed */
-static pid_t last_pid[NR_CPUS] = { [0 ... NR_CPUS-1] = -1 };
 
-static int graph_trace_init(struct trace_array *tr)
+
+/* Add a function return address to the trace stack on thread info.*/
+int
+ftrace_push_return_trace(unsigned long ret, unsigned long long time,
+                        unsigned long func, int *depth)
+{
+       int index;
+
+       if (!current->ret_stack)
+               return -EBUSY;
+
+       /* The return trace stack is full */
+       if (current->curr_ret_stack == FTRACE_RETFUNC_DEPTH - 1) {
+               atomic_inc(&current->trace_overrun);
+               return -EBUSY;
+       }
+
+       index = ++current->curr_ret_stack;
+       barrier();
+       current->ret_stack[index].ret = ret;
+       current->ret_stack[index].func = func;
+       current->ret_stack[index].calltime = time;
+       *depth = index;
+
+       return 0;
+}
+
+/* Retrieve a function return address to the trace stack on thread info.*/
+void
+ftrace_pop_return_trace(struct ftrace_graph_ret *trace, unsigned long *ret)
+{
+       int index;
+
+       index = current->curr_ret_stack;
+
+       if (unlikely(index < 0)) {
+               ftrace_graph_stop();
+               WARN_ON(1);
+               /* Might as well panic, otherwise we have no where to go */
+               *ret = (unsigned long)panic;
+               return;
+       }
+
+       *ret = current->ret_stack[index].ret;
+       trace->func = current->ret_stack[index].func;
+       trace->calltime = current->ret_stack[index].calltime;
+       trace->overrun = atomic_read(&current->trace_overrun);
+       trace->depth = index;
+       barrier();
+       current->curr_ret_stack--;
+
+}
+
+/*
+ * Send the trace to the ring-buffer.
+ * @return the original return address.
+ */
+unsigned long ftrace_return_to_handler(void)
 {
-       int cpu, ret;
+       struct ftrace_graph_ret trace;
+       unsigned long ret;
+
+       ftrace_pop_return_trace(&trace, &ret);
+       trace.rettime = trace_clock_local();
+       ftrace_graph_return(&trace);
+
+       if (unlikely(!ret)) {
+               ftrace_graph_stop();
+               WARN_ON(1);
+               /* Might as well panic. What else to do? */
+               ret = (unsigned long)panic;
+       }
 
-       for_each_online_cpu(cpu)
-               tracing_reset(tr, cpu);
+       return ret;
+}
 
-       ret = register_ftrace_graph(&trace_graph_return,
+static int graph_trace_init(struct trace_array *tr)
+{
+       int ret = register_ftrace_graph(&trace_graph_return,
                                        &trace_graph_entry);
        if (ret)
                return ret;
@@ -153,17 +231,25 @@ print_graph_proc(struct trace_seq *s, pid_t pid)
 
 /* If the pid changed since the last trace, output this event */
 static enum print_line_t
-verif_pid(struct trace_seq *s, pid_t pid, int cpu)
+verif_pid(struct trace_seq *s, pid_t pid, int cpu, pid_t *last_pids_cpu)
 {
        pid_t prev_pid;
+       pid_t *last_pid;
        int ret;
 
-       if (last_pid[cpu] != -1 && last_pid[cpu] == pid)
+       if (!last_pids_cpu)
+               return TRACE_TYPE_HANDLED;
+
+       last_pid = per_cpu_ptr(last_pids_cpu, cpu);
+
+       if (*last_pid == pid)
                return TRACE_TYPE_HANDLED;
 
-       prev_pid = last_pid[cpu];
-       last_pid[cpu] = pid;
+       prev_pid = *last_pid;
+       *last_pid = pid;
 
+       if (prev_pid == -1)
+               return TRACE_TYPE_HANDLED;
 /*
  * Context-switch trace line:
 
@@ -175,34 +261,34 @@ verif_pid(struct trace_seq *s, pid_t pid, int cpu)
        ret = trace_seq_printf(s,
                " ------------------------------------------\n");
        if (!ret)
-               TRACE_TYPE_PARTIAL_LINE;
+               return TRACE_TYPE_PARTIAL_LINE;
 
        ret = print_graph_cpu(s, cpu);
        if (ret == TRACE_TYPE_PARTIAL_LINE)
-               TRACE_TYPE_PARTIAL_LINE;
+               return TRACE_TYPE_PARTIAL_LINE;
 
        ret = print_graph_proc(s, prev_pid);
        if (ret == TRACE_TYPE_PARTIAL_LINE)
-               TRACE_TYPE_PARTIAL_LINE;
+               return TRACE_TYPE_PARTIAL_LINE;
 
        ret = trace_seq_printf(s, " => ");
        if (!ret)
-               TRACE_TYPE_PARTIAL_LINE;
+               return TRACE_TYPE_PARTIAL_LINE;
 
        ret = print_graph_proc(s, pid);
        if (ret == TRACE_TYPE_PARTIAL_LINE)
-               TRACE_TYPE_PARTIAL_LINE;
+               return TRACE_TYPE_PARTIAL_LINE;
 
        ret = trace_seq_printf(s,
                "\n ------------------------------------------\n\n");
        if (!ret)
-               TRACE_TYPE_PARTIAL_LINE;
+               return TRACE_TYPE_PARTIAL_LINE;
 
-       return ret;
+       return TRACE_TYPE_HANDLED;
 }
 
-static bool
-trace_branch_is_leaf(struct trace_iterator *iter,
+static struct ftrace_graph_ret_entry *
+get_return_for_leaf(struct trace_iterator *iter,
                struct ftrace_graph_ent_entry *curr)
 {
        struct ring_buffer_iter *ring_iter;
@@ -211,65 +297,123 @@ trace_branch_is_leaf(struct trace_iterator *iter,
 
        ring_iter = iter->buffer_iter[iter->cpu];
 
-       if (!ring_iter)
-               return false;
-
-       event = ring_buffer_iter_peek(ring_iter, NULL);
+       /* First peek to compare current entry and the next one */
+       if (ring_iter)
+               event = ring_buffer_iter_peek(ring_iter, NULL);
+       else {
+       /* We need to consume the current entry to see the next one */
+               ring_buffer_consume(iter->tr->buffer, iter->cpu, NULL);
+               event = ring_buffer_peek(iter->tr->buffer, iter->cpu,
+                                       NULL);
+       }
 
        if (!event)
-               return false;
+               return NULL;
 
        next = ring_buffer_event_data(event);
 
        if (next->ent.type != TRACE_GRAPH_RET)
-               return false;
+               return NULL;
 
        if (curr->ent.pid != next->ent.pid ||
                        curr->graph_ent.func != next->ret.func)
-               return false;
+               return NULL;
+
+       /* this is a leaf, now advance the iterator */
+       if (ring_iter)
+               ring_buffer_read(ring_iter, NULL);
 
-       return true;
+       return next;
+}
+
+/* Signal a overhead of time execution to the output */
+static int
+print_graph_overhead(unsigned long long duration, struct trace_seq *s)
+{
+       /* If duration disappear, we don't need anything */
+       if (!(tracer_flags.val & TRACE_GRAPH_PRINT_DURATION))
+               return 1;
+
+       /* Non nested entry or return */
+       if (duration == -1)
+               return trace_seq_printf(s, "  ");
+
+       if (tracer_flags.val & TRACE_GRAPH_PRINT_OVERHEAD) {
+               /* Duration exceeded 100 msecs */
+               if (duration > 100000ULL)
+                       return trace_seq_printf(s, "! ");
+
+               /* Duration exceeded 10 msecs */
+               if (duration > 10000ULL)
+                       return trace_seq_printf(s, "+ ");
+       }
+
+       return trace_seq_printf(s, "  ");
+}
+
+static int print_graph_abs_time(u64 t, struct trace_seq *s)
+{
+       unsigned long usecs_rem;
+
+       usecs_rem = do_div(t, NSEC_PER_SEC);
+       usecs_rem /= 1000;
+
+       return trace_seq_printf(s, "%5lu.%06lu |  ",
+                       (unsigned long)t, usecs_rem);
 }
 
 static enum print_line_t
-print_graph_irq(struct trace_seq *s, unsigned long addr,
-                               enum trace_type type, int cpu, pid_t pid)
+print_graph_irq(struct trace_iterator *iter, unsigned long addr,
+               enum trace_type type, int cpu, pid_t pid)
 {
        int ret;
+       struct trace_seq *s = &iter->seq;
 
        if (addr < (unsigned long)__irqentry_text_start ||
                addr >= (unsigned long)__irqentry_text_end)
                return TRACE_TYPE_UNHANDLED;
 
-       if (type == TRACE_GRAPH_ENT) {
-               ret = trace_seq_printf(s, "==========> |  ");
-       } else {
-               /* Cpu */
-               if (tracer_flags.val & TRACE_GRAPH_PRINT_CPU) {
-                       ret = print_graph_cpu(s, cpu);
-                       if (ret == TRACE_TYPE_PARTIAL_LINE)
-                               return TRACE_TYPE_PARTIAL_LINE;
-               }
-               /* Proc */
-               if (tracer_flags.val & TRACE_GRAPH_PRINT_PROC) {
-                       ret = print_graph_proc(s, pid);
-                       if (ret == TRACE_TYPE_PARTIAL_LINE)
-                               return TRACE_TYPE_PARTIAL_LINE;
+       /* Absolute time */
+       if (tracer_flags.val & TRACE_GRAPH_PRINT_ABS_TIME) {
+               ret = print_graph_abs_time(iter->ts, s);
+               if (!ret)
+                       return TRACE_TYPE_PARTIAL_LINE;
+       }
 
-                       ret = trace_seq_printf(s, " | ");
-                       if (!ret)
-                               return TRACE_TYPE_PARTIAL_LINE;
-               }
+       /* Cpu */
+       if (tracer_flags.val & TRACE_GRAPH_PRINT_CPU) {
+               ret = print_graph_cpu(s, cpu);
+               if (ret == TRACE_TYPE_PARTIAL_LINE)
+                       return TRACE_TYPE_PARTIAL_LINE;
+       }
+       /* Proc */
+       if (tracer_flags.val & TRACE_GRAPH_PRINT_PROC) {
+               ret = print_graph_proc(s, pid);
+               if (ret == TRACE_TYPE_PARTIAL_LINE)
+                       return TRACE_TYPE_PARTIAL_LINE;
+               ret = trace_seq_printf(s, " | ");
+               if (!ret)
+                       return TRACE_TYPE_PARTIAL_LINE;
+       }
 
-               /* No overhead */
-               if (tracer_flags.val & TRACE_GRAPH_PRINT_OVERHEAD) {
-                       ret = trace_seq_printf(s, "  ");
-                       if (!ret)
-                               return TRACE_TYPE_PARTIAL_LINE;
-               }
+       /* No overhead */
+       ret = print_graph_overhead(-1, s);
+       if (!ret)
+               return TRACE_TYPE_PARTIAL_LINE;
+
+       if (type == TRACE_GRAPH_ENT)
+               ret = trace_seq_printf(s, "==========>");
+       else
+               ret = trace_seq_printf(s, "<==========");
+
+       if (!ret)
+               return TRACE_TYPE_PARTIAL_LINE;
+
+       /* Don't close the duration column if haven't one */
+       if (tracer_flags.val & TRACE_GRAPH_PRINT_DURATION)
+               trace_seq_printf(s, " |");
+       ret = trace_seq_printf(s, "\n");
 
-               ret = trace_seq_printf(s, "<========== |\n");
-       }
        if (!ret)
                return TRACE_TYPE_PARTIAL_LINE;
        return TRACE_TYPE_HANDLED;
@@ -288,7 +432,7 @@ print_graph_duration(unsigned long long duration, struct trace_seq *s)
        sprintf(msecs_str, "%lu", (unsigned long) duration);
 
        /* Print msecs */
-       ret = trace_seq_printf(s, msecs_str);
+       ret = trace_seq_printf(s, "%s", msecs_str);
        if (!ret)
                return TRACE_TYPE_PARTIAL_LINE;
 
@@ -321,51 +465,33 @@ print_graph_duration(unsigned long long duration, struct trace_seq *s)
 
 }
 
-/* Signal a overhead of time execution to the output */
-static int
-print_graph_overhead(unsigned long long duration, struct trace_seq *s)
-{
-       /* Duration exceeded 100 msecs */
-       if (duration > 100000ULL)
-               return trace_seq_printf(s, "! ");
-
-       /* Duration exceeded 10 msecs */
-       if (duration > 10000ULL)
-               return trace_seq_printf(s, "+ ");
-
-       return trace_seq_printf(s, "  ");
-}
-
 /* Case of a leaf function on its call entry */
 static enum print_line_t
 print_graph_entry_leaf(struct trace_iterator *iter,
-               struct ftrace_graph_ent_entry *entry, struct trace_seq *s)
+               struct ftrace_graph_ent_entry *entry,
+               struct ftrace_graph_ret_entry *ret_entry, struct trace_seq *s)
 {
-       struct ftrace_graph_ret_entry *ret_entry;
        struct ftrace_graph_ret *graph_ret;
-       struct ring_buffer_event *event;
        struct ftrace_graph_ent *call;
        unsigned long long duration;
        int ret;
        int i;
 
-       event = ring_buffer_read(iter->buffer_iter[iter->cpu], NULL);
-       ret_entry = ring_buffer_event_data(event);
        graph_ret = &ret_entry->ret;
        call = &entry->graph_ent;
        duration = graph_ret->rettime - graph_ret->calltime;
 
        /* Overhead */
-       if (tracer_flags.val & TRACE_GRAPH_PRINT_OVERHEAD) {
-               ret = print_graph_overhead(duration, s);
-               if (!ret)
-                       return TRACE_TYPE_PARTIAL_LINE;
-       }
+       ret = print_graph_overhead(duration, s);
+       if (!ret)
+               return TRACE_TYPE_PARTIAL_LINE;
 
        /* Duration */
-       ret = print_graph_duration(duration, s);
-       if (ret == TRACE_TYPE_PARTIAL_LINE)
-               return TRACE_TYPE_PARTIAL_LINE;
+       if (tracer_flags.val & TRACE_GRAPH_PRINT_DURATION) {
+               ret = print_graph_duration(duration, s);
+               if (ret == TRACE_TYPE_PARTIAL_LINE)
+                       return TRACE_TYPE_PARTIAL_LINE;
+       }
 
        /* Function */
        for (i = 0; i < call->depth * TRACE_GRAPH_INDENT; i++) {
@@ -394,25 +520,17 @@ print_graph_entry_nested(struct ftrace_graph_ent_entry *entry,
        struct ftrace_graph_ent *call = &entry->graph_ent;
 
        /* No overhead */
-       if (tracer_flags.val & TRACE_GRAPH_PRINT_OVERHEAD) {
-               ret = trace_seq_printf(s, "  ");
-               if (!ret)
-                       return TRACE_TYPE_PARTIAL_LINE;
-       }
+       ret = print_graph_overhead(-1, s);
+       if (!ret)
+               return TRACE_TYPE_PARTIAL_LINE;
 
-       /* Interrupt */
-       ret = print_graph_irq(s, call->func, TRACE_GRAPH_ENT, cpu, pid);
-       if (ret == TRACE_TYPE_UNHANDLED) {
-               /* No time */
+       /* No time */
+       if (tracer_flags.val & TRACE_GRAPH_PRINT_DURATION) {
                ret = trace_seq_printf(s, "            |  ");
                if (!ret)
                        return TRACE_TYPE_PARTIAL_LINE;
-       } else {
-               if (ret == TRACE_TYPE_PARTIAL_LINE)
-                       return TRACE_TYPE_PARTIAL_LINE;
        }
 
-
        /* Function */
        for (i = 0; i < call->depth * TRACE_GRAPH_INDENT; i++) {
                ret = trace_seq_printf(s, " ");
@@ -428,20 +546,40 @@ print_graph_entry_nested(struct ftrace_graph_ent_entry *entry,
        if (!ret)
                return TRACE_TYPE_PARTIAL_LINE;
 
-       return TRACE_TYPE_HANDLED;
+       /*
+        * we already consumed the current entry to check the next one
+        * and see if this is a leaf.
+        */
+       return TRACE_TYPE_NO_CONSUME;
 }
 
 static enum print_line_t
 print_graph_entry(struct ftrace_graph_ent_entry *field, struct trace_seq *s,
-                       struct trace_iterator *iter, int cpu)
+                       struct trace_iterator *iter)
 {
        int ret;
+       int cpu = iter->cpu;
+       pid_t *last_entry = iter->private;
        struct trace_entry *ent = iter->ent;
+       struct ftrace_graph_ent *call = &field->graph_ent;
+       struct ftrace_graph_ret_entry *leaf_ret;
 
        /* Pid */
-       if (verif_pid(s, ent->pid, cpu) == TRACE_TYPE_PARTIAL_LINE)
+       if (verif_pid(s, ent->pid, cpu, last_entry) == TRACE_TYPE_PARTIAL_LINE)
+               return TRACE_TYPE_PARTIAL_LINE;
+
+       /* Interrupt */
+       ret = print_graph_irq(iter, call->func, TRACE_GRAPH_ENT, cpu, ent->pid);
+       if (ret == TRACE_TYPE_PARTIAL_LINE)
                return TRACE_TYPE_PARTIAL_LINE;
 
+       /* Absolute time */
+       if (tracer_flags.val & TRACE_GRAPH_PRINT_ABS_TIME) {
+               ret = print_graph_abs_time(iter->ts, s);
+               if (!ret)
+                       return TRACE_TYPE_PARTIAL_LINE;
+       }
+
        /* Cpu */
        if (tracer_flags.val & TRACE_GRAPH_PRINT_CPU) {
                ret = print_graph_cpu(s, cpu);
@@ -460,8 +598,9 @@ print_graph_entry(struct ftrace_graph_ent_entry *field, struct trace_seq *s,
                        return TRACE_TYPE_PARTIAL_LINE;
        }
 
-       if (trace_branch_is_leaf(iter, field))
-               return print_graph_entry_leaf(iter, field, s);
+       leaf_ret = get_return_for_leaf(iter, field);
+       if (leaf_ret)
+               return print_graph_entry_leaf(iter, field, leaf_ret, s);
        else
                return print_graph_entry_nested(field, s, iter->ent->pid, cpu);
 
@@ -469,16 +608,25 @@ print_graph_entry(struct ftrace_graph_ent_entry *field, struct trace_seq *s,
 
 static enum print_line_t
 print_graph_return(struct ftrace_graph_ret *trace, struct trace_seq *s,
-                  struct trace_entry *ent, int cpu)
+                  struct trace_entry *ent, struct trace_iterator *iter)
 {
        int i;
        int ret;
+       int cpu = iter->cpu;
+       pid_t *last_pid = iter->private, pid = ent->pid;
        unsigned long long duration = trace->rettime - trace->calltime;
 
        /* Pid */
-       if (verif_pid(s, ent->pid, cpu) == TRACE_TYPE_PARTIAL_LINE)
+       if (verif_pid(s, pid, cpu, last_pid) == TRACE_TYPE_PARTIAL_LINE)
                return TRACE_TYPE_PARTIAL_LINE;
 
+       /* Absolute time */
+       if (tracer_flags.val & TRACE_GRAPH_PRINT_ABS_TIME) {
+               ret = print_graph_abs_time(iter->ts, s);
+               if (!ret)
+                       return TRACE_TYPE_PARTIAL_LINE;
+       }
+
        /* Cpu */
        if (tracer_flags.val & TRACE_GRAPH_PRINT_CPU) {
                ret = print_graph_cpu(s, cpu);
@@ -498,16 +646,16 @@ print_graph_return(struct ftrace_graph_ret *trace, struct trace_seq *s,
        }
 
        /* Overhead */
-       if (tracer_flags.val & TRACE_GRAPH_PRINT_OVERHEAD) {
-               ret = print_graph_overhead(duration, s);
-               if (!ret)
-                       return TRACE_TYPE_PARTIAL_LINE;
-       }
+       ret = print_graph_overhead(duration, s);
+       if (!ret)
+               return TRACE_TYPE_PARTIAL_LINE;
 
        /* Duration */
-       ret = print_graph_duration(duration, s);
-       if (ret == TRACE_TYPE_PARTIAL_LINE)
-               return TRACE_TYPE_PARTIAL_LINE;
+       if (tracer_flags.val & TRACE_GRAPH_PRINT_DURATION) {
+               ret = print_graph_duration(duration, s);
+               if (ret == TRACE_TYPE_PARTIAL_LINE)
+                       return TRACE_TYPE_PARTIAL_LINE;
+       }
 
        /* Closing brace */
        for (i = 0; i < trace->depth * TRACE_GRAPH_INDENT; i++) {
@@ -528,7 +676,7 @@ print_graph_return(struct ftrace_graph_ret *trace, struct trace_seq *s,
                        return TRACE_TYPE_PARTIAL_LINE;
        }
 
-       ret = print_graph_irq(s, trace->func, TRACE_GRAPH_RET, cpu, ent->pid);
+       ret = print_graph_irq(iter, trace->func, TRACE_GRAPH_RET, cpu, pid);
        if (ret == TRACE_TYPE_PARTIAL_LINE)
                return TRACE_TYPE_PARTIAL_LINE;
 
@@ -541,14 +689,23 @@ print_graph_comment(struct print_entry *trace, struct trace_seq *s,
 {
        int i;
        int ret;
+       int cpu = iter->cpu;
+       pid_t *last_pid = iter->private;
 
        /* Pid */
-       if (verif_pid(s, ent->pid, iter->cpu) == TRACE_TYPE_PARTIAL_LINE)
+       if (verif_pid(s, ent->pid, cpu, last_pid) == TRACE_TYPE_PARTIAL_LINE)
                return TRACE_TYPE_PARTIAL_LINE;
 
+       /* Absolute time */
+       if (tracer_flags.val & TRACE_GRAPH_PRINT_ABS_TIME) {
+               ret = print_graph_abs_time(iter->ts, s);
+               if (!ret)
+                       return TRACE_TYPE_PARTIAL_LINE;
+       }
+
        /* Cpu */
        if (tracer_flags.val & TRACE_GRAPH_PRINT_CPU) {
-               ret = print_graph_cpu(s, iter->cpu);
+               ret = print_graph_cpu(s, cpu);
                if (ret == TRACE_TYPE_PARTIAL_LINE)
                        return TRACE_TYPE_PARTIAL_LINE;
        }
@@ -565,17 +722,17 @@ print_graph_comment(struct print_entry *trace, struct trace_seq *s,
        }
 
        /* No overhead */
-       if (tracer_flags.val & TRACE_GRAPH_PRINT_OVERHEAD) {
-               ret = trace_seq_printf(s, "  ");
+       ret = print_graph_overhead(-1, s);
+       if (!ret)
+               return TRACE_TYPE_PARTIAL_LINE;
+
+       /* No time */
+       if (tracer_flags.val & TRACE_GRAPH_PRINT_DURATION) {
+               ret = trace_seq_printf(s, "            |  ");
                if (!ret)
                        return TRACE_TYPE_PARTIAL_LINE;
        }
 
-       /* No time */
-       ret = trace_seq_printf(s, "            |  ");
-       if (!ret)
-               return TRACE_TYPE_PARTIAL_LINE;
-
        /* Indentation */
        if (trace->depth > 0)
                for (i = 0; i < (trace->depth + 1) * TRACE_GRAPH_INDENT; i++) {
@@ -585,12 +742,19 @@ print_graph_comment(struct print_entry *trace, struct trace_seq *s,
                }
 
        /* The comment */
-       ret = trace_seq_printf(s, "/* %s", trace->buf);
+       ret = trace_seq_printf(s, "/* ");
+       if (!ret)
+               return TRACE_TYPE_PARTIAL_LINE;
+
+       ret = trace_seq_bprintf(s, trace->fmt, trace->buf);
        if (!ret)
                return TRACE_TYPE_PARTIAL_LINE;
 
-       if (ent->flags & TRACE_FLAG_CONT)
-               trace_seq_print_cont(s, iter);
+       /* Strip ending newline */
+       if (s->buffer[s->len - 1] == '\n') {
+               s->buffer[s->len - 1] = '\0';
+               s->len--;
+       }
 
        ret = trace_seq_printf(s, " */\n");
        if (!ret)
@@ -610,13 +774,12 @@ print_graph_function(struct trace_iterator *iter)
        case TRACE_GRAPH_ENT: {
                struct ftrace_graph_ent_entry *field;
                trace_assign_type(field, entry);
-               return print_graph_entry(field, s, iter,
-                                        iter->cpu);
+               return print_graph_entry(field, s, iter);
        }
        case TRACE_GRAPH_RET: {
                struct ftrace_graph_ret_entry *field;
                trace_assign_type(field, entry);
-               return print_graph_return(&field->ret, s, entry, iter->cpu);
+               return print_graph_return(&field->ret, s, entry, iter);
        }
        case TRACE_PRINT: {
                struct print_entry *field;
@@ -632,33 +795,64 @@ static void print_graph_headers(struct seq_file *s)
 {
        /* 1st line */
        seq_printf(s, "# ");
+       if (tracer_flags.val & TRACE_GRAPH_PRINT_ABS_TIME)
+               seq_printf(s, "     TIME       ");
        if (tracer_flags.val & TRACE_GRAPH_PRINT_CPU)
-               seq_printf(s, "CPU ");
+               seq_printf(s, "CPU");
        if (tracer_flags.val & TRACE_GRAPH_PRINT_PROC)
-               seq_printf(s, "TASK/PID     ");
-       if (tracer_flags.val & TRACE_GRAPH_PRINT_OVERHEAD)
-               seq_printf(s, "OVERHEAD/");
-       seq_printf(s, "DURATION            FUNCTION CALLS\n");
+               seq_printf(s, "  TASK/PID      ");
+       if (tracer_flags.val & TRACE_GRAPH_PRINT_DURATION)
+               seq_printf(s, "  DURATION   ");
+       seq_printf(s, "               FUNCTION CALLS\n");
 
        /* 2nd line */
        seq_printf(s, "# ");
+       if (tracer_flags.val & TRACE_GRAPH_PRINT_ABS_TIME)
+               seq_printf(s, "      |         ");
        if (tracer_flags.val & TRACE_GRAPH_PRINT_CPU)
-               seq_printf(s, "|   ");
+               seq_printf(s, "|  ");
        if (tracer_flags.val & TRACE_GRAPH_PRINT_PROC)
-               seq_printf(s, "|      |     ");
-       if (tracer_flags.val & TRACE_GRAPH_PRINT_OVERHEAD) {
-               seq_printf(s, "|        ");
-               seq_printf(s, "|                   |   |   |   |\n");
-       } else
-               seq_printf(s, "    |               |   |   |   |\n");
+               seq_printf(s, "  |    |        ");
+       if (tracer_flags.val & TRACE_GRAPH_PRINT_DURATION)
+               seq_printf(s, "   |   |      ");
+       seq_printf(s, "               |   |   |   |\n");
 }
+
+static void graph_trace_open(struct trace_iterator *iter)
+{
+       /* pid on the last trace processed */
+       pid_t *last_pid = alloc_percpu(pid_t);
+       int cpu;
+
+       if (!last_pid)
+               pr_warning("function graph tracer: not enough memory\n");
+       else
+               for_each_possible_cpu(cpu) {
+                       pid_t *pid = per_cpu_ptr(last_pid, cpu);
+                       *pid = -1;
+               }
+
+       iter->private = last_pid;
+}
+
+static void graph_trace_close(struct trace_iterator *iter)
+{
+       free_percpu(iter->private);
+}
+
 static struct tracer graph_trace __read_mostly = {
        .name           = "function_graph",
+       .open           = graph_trace_open,
+       .close          = graph_trace_close,
+       .wait_pipe      = poll_wait_pipe,
        .init           = graph_trace_init,
        .reset          = graph_trace_reset,
        .print_line     = print_graph_function,
        .print_header   = print_graph_headers,
        .flags          = &tracer_flags,
+#ifdef CONFIG_FTRACE_SELFTEST
+       .selftest       = trace_selftest_startup_function_graph,
+#endif
 };
 
 static __init int init_graph_trace(void)