builtin-report.c

/*
 * builtin-report.c
 *
 * Builtin report command: Analyze the perf.data input file,
 * look up and read DSOs and symbol information and display
 * a histogram of results, along various sorting keys.
 */
#include "builtin.h"

#include "util/util.h"

#include "util/color.h"
#include <linux/list.h>
#include "util/cache.h"
#include <linux/rbtree.h>
#include "util/symbol.h"
#include "util/string.h"
#include "util/callchain.h"
#include "util/strlist.h"
#include "util/values.h"

#include "perf.h"
#include "util/debug.h"
#include "util/header.h"

#include "util/parse-options.h"
#include "util/parse-events.h"

#include "util/thread.h"

static char		const *input_name = "perf.data";

static char		default_sort_order[] = "comm,dso,symbol";
static char		*sort_order = default_sort_order;
static char		*dso_list_str, *comm_list_str, *sym_list_str,
			*col_width_list_str;
static struct strlist	*dso_list, *comm_list, *sym_list;
static char		*field_sep;

static int		force;
static int		input;
static int		show_mask = SHOW_KERNEL | SHOW_USER | SHOW_HV;

static int		full_paths;
static int		show_nr_samples;

static int		show_threads;
static struct perf_read_values	show_threads_values;

static char		default_pretty_printing_style[] = "normal";
static char		*pretty_printing_style = default_pretty_printing_style;

static unsigned long	page_size;
static unsigned long	mmap_window = 32;

static char		default_parent_pattern[] = "^sys_|^do_page_fault";
static char		*parent_pattern = default_parent_pattern;
static regex_t		parent_regex;

static int		exclude_other = 1;

static char		callchain_default_opt[] = "fractal,0.5";

static int		callchain;

static char		__cwd[PATH_MAX];
static char		*cwd = __cwd;
static int		cwdlen;

static struct rb_root	threads;
static struct thread	*last_match;

static struct perf_header *header;

static
struct callchain_param	callchain_param = {
	.mode	= CHAIN_GRAPH_REL,
	.min_percent = 0.5
};

static u64		sample_type;

static int repsep_fprintf(FILE *fp, const char *fmt, ...)
{
	int n;
	va_list ap;

	va_start(ap, fmt);
	if (!field_sep)
		n = vfprintf(fp, fmt, ap);
	else {
		char *bf = NULL;
		n = vasprintf(&bf, fmt, ap);
		if (n > 0) {
			char *sep = bf;

			while (1) {
				sep = strchr(sep, *field_sep);
				if (sep == NULL)
					break;
				*sep = '.';
			}
		}
		fputs(bf, fp);
		free(bf);
	}
	va_end(ap);
	return n;
}

static unsigned int dsos__col_width,
		    comms__col_width,
		    threads__col_width;

/*
 * histogram, sorted on item, collects counts
 */

static struct rb_root hist;

struct hist_entry {
	struct rb_node		rb_node;

	struct thread		*thread;
	struct map		*map;
	struct dso		*dso;
	struct symbol		*sym;
	struct symbol		*parent;
	u64			ip;
	char			level;
	struct callchain_node	callchain;
	struct rb_root		sorted_chain;

	u64			count;
};

/*
 * configurable sorting bits
 */

struct sort_entry {
	struct list_head list;

	const char *header;

	int64_t (*cmp)(struct hist_entry *, struct hist_entry *);
	int64_t (*collapse)(struct hist_entry *, struct hist_entry *);
	size_t	(*print)(FILE *fp, struct hist_entry *, unsigned int width);
	unsigned int *width;
	bool	elide;
};

static int64_t cmp_null(void *l, void *r)
{
	if (!l && !r)
		return 0;
	else if (!l)
		return -1;
	else
		return 1;
}

/* --sort pid */

static int64_t
sort__thread_cmp(struct hist_entry *left, struct hist_entry *right)
{
	return right->thread->pid - left->thread->pid;
}

static size_t
sort__thread_print(FILE *fp, struct hist_entry *self, unsigned int width)
{
	return repsep_fprintf(fp, "%*s:%5d", width - 6,
			      self->thread->comm ?: "", self->thread->pid);
}

static struct sort_entry sort_thread = {
	.header = "Command:  Pid",
	.cmp	= sort__thread_cmp,
	.print	= sort__thread_print,
	.width	= &threads__col_width,
};

/* --sort comm */

static int64_t
sort__comm_cmp(struct hist_entry *left, struct hist_entry *right)
{
	return right->thread->pid - left->thread->pid;
}

static int64_t
sort__comm_collapse(struct hist_entry *left, struct hist_entry *right)
{
	char *comm_l = left->thread->comm;
	char *comm_r = right->thread->comm;

	if (!comm_l || !comm_r)
		return cmp_null(comm_l, comm_r);

	return strcmp(comm_l, comm_r);
}

static size_t
sort__comm_print(FILE *fp, struct hist_entry *self, unsigned int width)
{
	return repsep_fprintf(fp, "%*s", width, self->thread->comm);
}

static struct sort_entry sort_comm = {
	.header		= "Command",
	.cmp		= sort__comm_cmp,
	.collapse	= sort__comm_collapse,
	.print		= sort__comm_print,
	.width		= &comms__col_width,
};

/* --sort dso */

static int64_t
sort__dso_cmp(struct hist_entry *left, struct hist_entry *right)
{
	struct dso *dso_l = left->dso;
	struct dso *dso_r = right->dso;

	if (!dso_l || !dso_r)
		return cmp_null(dso_l, dso_r);

	return strcmp(dso_l->name, dso_r->name);
}

static size_t
sort__dso_print(FILE *fp, struct hist_entry *self, unsigned int width)
{
	if (self->dso)
		return repsep_fprintf(fp, "%-*s", width, self->dso->name);

	return repsep_fprintf(fp, "%*llx", width, (u64)self->ip);
}

static struct sort_entry sort_dso = {
	.header = "Shared Object",
	.cmp	= sort__dso_cmp,
	.print	= sort__dso_print,
	.width	= &dsos__col_width,
};

/* --sort symbol */

static int64_t
sort__sym_cmp(struct hist_entry *left, struct hist_entry *right)
{
	u64 ip_l, ip_r;

	if (left->sym == right->sym)
		return 0;

	ip_l = left->sym ? left->sym->start : left->ip;
	ip_r = right->sym ? right->sym->start : right->ip;

	return (int64_t)(ip_r - ip_l);
}

static size_t
sort__sym_print(FILE *fp, struct hist_entry *self, unsigned int width __used)
{
	size_t ret = 0;

	if (verbose)
		ret += repsep_fprintf(fp, "%#018llx %c ", (u64)self->ip,
				      dso__symtab_origin(self->dso));

	ret += repsep_fprintf(fp, "[%c] ", self->level);
	if (self->sym) {
		ret += repsep_fprintf(fp, "%s", self->sym->name);

		if (self->sym->module)
			ret += repsep_fprintf(fp, "\t[%s]",
					     self->sym->module->name);
	} else {
		ret += repsep_fprintf(fp, "%#016llx", (u64)self->ip);
	}

	return ret;
}

static struct sort_entry sort_sym = {
	.header = "Symbol",
	.cmp	= sort__sym_cmp,
	.print	= sort__sym_print,
};

/* --sort parent */

static int64_t
sort__parent_cmp(struct hist_entry *left, struct hist_entry *right)
{
	struct symbol *sym_l = left->parent;
	struct symbol *sym_r = right->parent;

	if (!sym_l || !sym_r)
		return cmp_null(sym_l, sym_r);

	return strcmp(sym_l->name, sym_r->name);
}

static size_t
sort__parent_print(FILE *fp, struct hist_entry *self, unsigned int width)
{
	return repsep_fprintf(fp, "%-*s", width,
			      self->parent ? self->parent->name : "[other]");
}

static unsigned int parent_symbol__col_width;

static struct sort_entry sort_parent = {
	.header = "Parent symbol",
	.cmp	= sort__parent_cmp,
	.print	= sort__parent_print,
	.width	= &parent_symbol__col_width,
};

static int sort__need_collapse = 0;
static int sort__has_parent = 0;

struct sort_dimension {
	const char		*name;
	struct sort_entry	*entry;
	int			taken;
};

static struct sort_dimension sort_dimensions[] = {
	{ .name = "pid",	.entry = &sort_thread,	},
	{ .name = "comm",	.entry = &sort_comm,	},
	{ .name = "dso",	.entry = &sort_dso,	},
	{ .name = "symbol",	.entry = &sort_sym,	},
	{ .name = "parent",	.entry = &sort_parent,	},
};

static LIST_HEAD(hist_entry__sort_list);

static int sort_dimension__add(const char *tok)
{
	unsigned int i;

	for (i = 0; i < ARRAY_SIZE(sort_dimensions); i++) {
		struct sort_dimension *sd = &sort_dimensions[i];

		if (sd->taken)
			continue;

		if (strncasecmp(tok, sd->name, strlen(tok)))
			continue;

		if (sd->entry->collapse)
			sort__need_collapse = 1;

		if (sd->entry == &sort_parent) {
			int ret = regcomp(&parent_regex, parent_pattern, REG_EXTENDED);
			if (ret) {
				char err[BUFSIZ];

				regerror(ret, &parent_regex, err, sizeof(err));
				fprintf(stderr, "Invalid regex: %s\n%s",
					parent_pattern, err);
				exit(-1);
			}
			sort__has_parent = 1;
		}

		list_add_tail(&sd->entry->list, &hist_entry__sort_list);
		sd->taken = 1;

		return 0;
	}

	return -ESRCH;
}

static int64_t
hist_entry__cmp(struct hist_entry *left, struct hist_entry *right)
{
	struct sort_entry *se;
	int64_t cmp = 0;

	list_for_each_entry(se, &hist_entry__sort_list, list) {
		cmp = se->cmp(left, right);
		if (cmp)
			break;
	}

	return cmp;
}

static int64_t
hist_entry__collapse(struct hist_entry *left, struct hist_entry *right)
{
	struct sort_entry *se;
	int64_t cmp = 0;

	list_for_each_entry(se, &hist_entry__sort_list, list) {
		int64_t (*f)(struct hist_entry *, struct hist_entry *);

		f = se->collapse ?: se->cmp;

		cmp = f(left, right);
		if (cmp)
			break;
	}

	return cmp;
}

static size_t ipchain__fprintf_graph_line(FILE *fp, int depth, int depth_mask)
{
	int i;
	size_t ret = 0;

	ret += fprintf(fp, "%s", "                ");

	for (i = 0; i < depth; i++)
		if (depth_mask & (1 << i))
			ret += fprintf(fp, "|          ");
		else
			ret += fprintf(fp, "           ");

	ret += fprintf(fp, "\n");

	return ret;
}
static size_t
ipchain__fprintf_graph(FILE *fp, struct callchain_list *chain, int depth,
		       int depth_mask, int count, u64 total_samples,
		       int hits)
{
	int i;
	size_t ret = 0;

	ret += fprintf(fp, "%s", "                ");
	for (i = 0; i < depth; i++) {
		if (depth_mask & (1 << i))
			ret += fprintf(fp, "|");
		else
			ret += fprintf(fp, " ");
		if (!count && i == depth - 1) {
			double percent;

			percent = hits * 100.0 / total_samples;
			ret += percent_color_fprintf(fp, "--%2.2f%%-- ", percent);
		} else
			ret += fprintf(fp, "%s", "          ");
	}
	if (chain->sym)
		ret += fprintf(fp, "%s\n", chain->sym->name);
	else
		ret += fprintf(fp, "%p\n", (void *)(long)chain->ip);

	return ret;
}

static struct symbol *rem_sq_bracket;
static struct callchain_list rem_hits;

static void init_rem_hits(void)
{
	rem_sq_bracket = malloc(sizeof(*rem_sq_bracket) + 6);
	if (!rem_sq_bracket) {
		fprintf(stderr, "Not enough memory to display remaining hits\n");
		return;
	}

	strcpy(rem_sq_bracket->name, "[...]");
	rem_hits.sym = rem_sq_bracket;
}

static size_t
callchain__fprintf_graph(FILE *fp, struct callchain_node *self,
			u64 total_samples, int depth, int depth_mask)
{
	struct rb_node *node, *next;
	struct callchain_node *child;
	struct callchain_list *chain;
	int new_depth_mask = depth_mask;
	u64 new_total;
	u64 remaining;
	size_t ret = 0;
	int i;

	if (callchain_param.mode == CHAIN_GRAPH_REL)
		new_total = self->children_hit;
	else
		new_total = total_samples;

	remaining = new_total;

	node = rb_first(&self->rb_root);
	while (node) {
		u64 cumul;

		child = rb_entry(node, struct callchain_node, rb_node);
		cumul = cumul_hits(child);
		remaining -= cumul;

		/*
		 * The depth mask manages the output of pipes that show
		 * the depth. We don't want to keep the pipes of the current
		 * level for the last child of this depth.
		 * Except if we have remaining filtered hits. They will
		 * supersede the last child
		 */
		next = rb_next(node);
		if (!next && (callchain_param.mode != CHAIN_GRAPH_REL || !remaining))
			new_depth_mask &= ~(1 << (depth - 1));

		/*
		 * But we keep the older depth mask for the line seperator
		 * to keep the level link until we reach the last child
		 */
		ret += ipchain__fprintf_graph_line(fp, depth, depth_mask);
		i = 0;
		list_for_each_entry(chain, &child->val, list) {
			if (chain->ip >= PERF_CONTEXT_MAX)
				continue;
			ret += ipchain__fprintf_graph(fp, chain, depth,
						      new_depth_mask, i++,
						      new_total,
						      cumul);
		}
		ret += callchain__fprintf_graph(fp, child, new_total,
						depth + 1,
						new_depth_mask | (1 << depth));
		node = next;
	}

	if (callchain_param.mode == CHAIN_GRAPH_REL &&
		remaining && remaining != new_total) {

		if (!rem_sq_bracket)
			return ret;

		new_depth_mask &= ~(1 << (depth - 1));

		ret += ipchain__fprintf_graph(fp, &rem_hits, depth,
					      new_depth_mask, 0, new_total,
					      remaining);
	}

	return ret;
}

static size_t
callchain__fprintf_flat(FILE *fp, struct callchain_node *self,
			u64 total_samples)
{
	struct callchain_list *chain;
	size_t ret = 0;

	if (!self)
		return 0;

	ret += callchain__fprintf_flat(fp, self->parent, total_samples);


	list_for_each_entry(chain, &self->val, list) {
		if (chain->ip >= PERF_CONTEXT_MAX)
			continue;
		if (chain->sym)
			ret += fprintf(fp, "                %s\n", chain->sym->name);
		else
			ret += fprintf(fp, "                %p\n",
					(void *)(long)chain->ip);
	}

	return ret;
}

static size_t
hist_entry_callchain__fprintf(FILE *fp, struct hist_entry *self,
			      u64 total_samples)
{
	struct rb_node *rb_node;
	struct callchain_node *chain;
	size_t ret = 0;

	rb_node = rb_first(&self->sorted_chain);
	while (rb_node) {
		double percent;

		chain = rb_entry(rb_node, struct callchain_node, rb_node);
		percent = chain->hit * 100.0 / total_samples;
		switch (callchain_param.mode) {
		case CHAIN_FLAT:
			ret += percent_color_fprintf(fp, "           %6.2f%%\n",
						     percent);
			ret += callchain__fprintf_flat(fp, chain, total_samples);
			break;
		case CHAIN_GRAPH_ABS: /* Falldown */
		case CHAIN_GRAPH_REL:
			ret += callchain__fprintf_graph(fp, chain,
							total_samples, 1, 1);
		case CHAIN_NONE:
		default:
			break;
		}
		ret += fprintf(fp, "\n");
		rb_node = rb_next(rb_node);
	}

	return ret;
}


static size_t
hist_entry__fprintf(FILE *fp, struct hist_entry *self, u64 total_samples)
{
	struct sort_entry *se;
	size_t ret;

	if (exclude_other && !self->parent)
		return 0;

	if (total_samples)
		ret = percent_color_fprintf(fp,
					    field_sep ? "%.2f" : "   %6.2f%%",
					(self->count * 100.0) / total_samples);
	else
		ret = fprintf(fp, field_sep ? "%lld" : "%12lld ", self->count);

	if (show_nr_samples) {
		if (field_sep)
			fprintf(fp, "%c%lld", *field_sep, self->count);
		else
			fprintf(fp, "%11lld", self->count);
	}

	list_for_each_entry(se, &hist_entry__sort_list, list) {
		if (se->elide)
			continue;

		fprintf(fp, "%s", field_sep ?: "  ");
		ret += se->print(fp, self, se->width ? *se->width : 0);
	}

	ret += fprintf(fp, "\n");

	if (callchain)
		hist_entry_callchain__fprintf(fp, self, total_samples);

	return ret;
}

/*
 *
 */

static void dso__calc_col_width(struct dso *self)
{
	if (!col_width_list_str && !field_sep &&
	    (!dso_list || strlist__has_entry(dso_list, self->name))) {
		unsigned int slen = strlen(self->name);
		if (slen > dsos__col_width)
			dsos__col_width = slen;
	}

	self->slen_calculated = 1;
}

static int thread__set_comm_adjust(struct thread *self, const char *comm)
{
	int ret = thread__set_comm(self, comm);

	if (ret)
		return ret;

	if (!col_width_list_str && !field_sep &&
	    (!comm_list || strlist__has_entry(comm_list, comm))) {
		unsigned int slen = strlen(comm);

		if (slen > comms__col_width) {
			comms__col_width = slen;
			threads__col_width = slen + 6;
		}
	}

	return 0;
}


static struct symbol *
resolve_symbol(struct thread *thread, struct map **mapp,
	       struct dso **dsop, u64 *ipp)
{
	struct dso *dso = dsop ? *dsop : NULL;
	struct map *map = mapp ? *mapp : NULL;
	u64 ip = *ipp;

	if (!thread)
		return NULL;

	if (dso)
		goto got_dso;

	if (map)
		goto got_map;

	map = thread__find_map(thread, ip);
	if (map != NULL) {
		/*
		 * We have to do this here as we may have a dso
		 * with no symbol hit that has a name longer than
		 * the ones with symbols sampled.
		 */
		if (!sort_dso.elide && !map->dso->slen_calculated)
			dso__calc_col_width(map->dso);

		if (mapp)
			*mapp = map;
got_map:
		ip = map->map_ip(map, ip);

		dso = map->dso;
	} else {
		/*
		 * If this is outside of all known maps,
		 * and is a negative address, try to look it
		 * up in the kernel dso, as it might be a
		 * vsyscall (which executes in user-mode):
		 */
		if ((long long)ip < 0)
		dso = kernel_dso;
	}
	dump_printf(" ...... dso: %s\n", dso ? dso->name : "<not found>");
	dump_printf(" ...... map: %Lx -> %Lx\n", *ipp, ip);
	*ipp  = ip;

	if (dsop)
		*dsop = dso;

	if (!dso)
		return NULL;
got_dso:
	return dso->find_symbol(dso, ip);
}

static int call__match(struct symbol *sym)
{
	if (sym->name && !regexec(&parent_regex, sym->name, 0, NULL, 0))
		return 1;

	return 0;
}

static struct symbol **
resolve_callchain(struct thread *thread, struct map *map __used,
		    struct ip_callchain *chain, struct hist_entry *entry)
{
	u64 context = PERF_CONTEXT_MAX;
	struct symbol **syms = NULL;
	unsigned int i;

	if (callchain) {
		syms = calloc(chain->nr, sizeof(*syms));
		if (!syms) {
			fprintf(stderr, "Can't allocate memory for symbols\n");
			exit(-1);
		}
	}

	for (i = 0; i < chain->nr; i++) {
		u64 ip = chain->ips[i];
		struct dso *dso = NULL;
		struct symbol *sym;

		if (ip >= PERF_CONTEXT_MAX) {
			context = ip;
			continue;
		}

		switch (context) {
		case PERF_CONTEXT_HV:
			dso = hypervisor_dso;
			break;
		case PERF_CONTEXT_KERNEL:
			dso = kernel_dso;
			break;
		default:
			break;
		}

		sym = resolve_symbol(thread, NULL, &dso, &ip);

		if (sym) {
			if (sort__has_parent && call__match(sym) &&
			    !entry->parent)
				entry->parent = sym;
			if (!callchain)
				break;
			syms[i] = sym;
		}
	}

	return syms;
}

/*
 * collect histogram counts
 */

static int
hist_entry__add(struct thread *thread, struct map *map, struct dso *dso,
		struct symbol *sym, u64 ip, struct ip_callchain *chain,
		char level, u64 count)
{
	struct rb_node **p = &hist.rb_node;
	struct rb_node *parent = NULL;
	struct hist_entry *he;
	struct symbol **syms = NULL;
	struct hist_entry entry = {
		.thread	= thread,
		.map	= map,
		.dso	= dso,
		.sym	= sym,
		.ip	= ip,
		.level	= level,
		.count	= count,
		.parent = NULL,
		.sorted_chain = RB_ROOT
	};
	int cmp;

	if ((sort__has_parent || callchain) && chain)
		syms = resolve_callchain(thread, map, chain, &entry);

	while (*p != NULL) {
		parent = *p;
		he = rb_entry(parent, struct hist_entry, rb_node);

		cmp = hist_entry__cmp(&entry, he);

		if (!cmp) {
			he->count += count;
			if (callchain) {
				append_chain(&he->callchain, chain, syms);
				free(syms);
			}
			return 0;
		}

		if (cmp < 0)
			p = &(*p)->rb_left;
		else
			p = &(*p)->rb_right;
	}

	he = malloc(sizeof(*he));
	if (!he)
		return -ENOMEM;
	*he = entry;
	if (callchain) {
		callchain_init(&he->callchain);
		append_chain(&he->callchain, chain, syms);
		free(syms);
	}
	rb_link_node(&he->rb_node, parent, p);
	rb_insert_color(&he->rb_node, &hist);

	return 0;
}

static void hist_entry__free(struct hist_entry *he)
{
	free(he);
}

/*
 * collapse the histogram
 */

static struct rb_root collapse_hists;

static void collapse__insert_entry(struct hist_entry *he)
{
	struct rb_node **p = &collapse_hists.rb_node;
	struct rb_node *parent = NULL;
	struct hist_entry *iter;
	int64_t cmp;

	while (*p != NULL) {
		parent = *p;
		iter = rb_entry(parent, struct hist_entry, rb_node);

		cmp = hist_entry__collapse(iter, he);

		if (!cmp) {
			iter->count += he->count;
			hist_entry__free(he);
			return;
		}

		if (cmp < 0)
			p = &(*p)->rb_left;
		else
			p = &(*p)->rb_right;
	}

	rb_link_node(&he->rb_node, parent, p);
	rb_insert_color(&he->rb_node, &collapse_hists);
}

static void collapse__resort(void)
{
	struct rb_node *next;
	struct hist_entry *n;

	if (!sort__need_collapse)
		return;

	next = rb_first(&hist);
	while (next) {
		n = rb_entry(next, struct hist_entry, rb_node);
		next = rb_next(&n->rb_node);

		rb_erase(&n->rb_node, &hist);
		collapse__insert_entry(n);
	}
}

/*
 * reverse the map, sort on count.
 */

static struct rb_root output_hists;

static void output__insert_entry(struct hist_entry *he, u64 min_callchain_hits)
{
	struct rb_node **p = &output_hists.rb_node;
	struct rb_node *parent = NULL;
	struct hist_entry *iter;

	if (callchain)
		callchain_param.sort(&he->sorted_chain, &he->callchain,
				      min_callchain_hits, &callchain_param);

	while (*p != NULL) {
		parent = *p;
		iter = rb_entry(parent, struct hist_entry, rb_node);

		if (he->count > iter->count)
			p = &(*p)->rb_left;
		else
			p = &(*p)->rb_right;
	}

	rb_link_node(&he->rb_node, parent, p);
	rb_insert_color(&he->rb_node, &output_hists);
}

static void output__resort(u64 total_samples)
{
	struct rb_node *next;
	struct hist_entry *n;
	struct rb_root *tree = &hist;
	u64 min_callchain_hits;

	min_callchain_hits = total_samples * (callchain_param.min_percent / 100);

	if (sort__need_collapse)
		tree = &collapse_hists;

	next = rb_first(tree);

	while (next) {
		n = rb_entry(next, struct hist_entry, rb_node);
		next = rb_next(&n->rb_node);

		rb_erase(&n->rb_node, tree);
		output__insert_entry(n, min_callchain_hits);
	}
}

static size_t output__fprintf(FILE *fp, u64 total_samples)
{
	struct hist_entry *pos;
	struct sort_entry *se;
	struct rb_node *nd;
	size_t ret = 0;
	unsigned int width;
	char *col_width = col_width_list_str;
	int raw_printing_style;

	raw_printing_style = !strcmp(pretty_printing_style, "raw");

	init_rem_hits();

	fprintf(fp, "# Samples: %Ld\n", (u64)total_samples);
	fprintf(fp, "#\n");

	fprintf(fp, "# Overhead");
	if (show_nr_samples) {