Merge branch 'perf-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip

8aedf8a6 · Linus Torvalds <[email protected]> · 2009-12-16 12:32:47 -08:00

* 'perf-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: (52 commits)
  perf record: Use per-task-per-cpu events for inherited events
  perf record: Properly synchronize child creation
  perf events: Allow per-task-per-cpu counters
  perf diff: Percent calcs should use double values
  perf diff: Change the default sort order to "dso,symbol"
  perf diff: Use perf_session__fprintf_hists just like 'perf record'
  perf report: Fix cut'n'paste error recently introduced
  perf session: Move perf report specific hits out of perf_session__fprintf_hists
  perf tools: Move hist entries printing routines from perf report
  perf report: Generalize perf_session__fprintf_hists()
  perf symbols: Move symbol filtering to event__preprocess_sample()
  perf symbols: Adopt the strlists for dso, comm
  perf symbols: Make symbol_conf global
  perf probe: Fix to show which probe point is not found
  perf probe: Check symbols in symtab/kallsyms
  perf probe: Check build-id of vmlinux
  perf probe: Reject second attempt of adding same-name event
  perf probe: Support event name for --add option
  perf probe: Add glob matching support on --del
  perf probe: Use strlist__for_each macros in probe-event.c
  ...

Commit: 8aedf8a6ae98d5d4df3254b6afb7e4432d9d8600
Parents: bac5e54c · 60ab2716

Merge commit. Changes below are compared with the first parent: bac5e54c.

Changes

53 files changed · +2293 −1413

File	Status	Add	Del	Content
include/linux/perf_event.h	modified	+3	−9	View file
kernel/perf_event.c	modified	+9	−6	View file
tools/perf/Documentation/perf-diff.txt	added	+55	−0	View file
tools/perf/Documentation/perf-probe.txt	modified	+2	−1	View file
tools/perf/Documentation/perf-report.txt	modified	+4	−0	View file
tools/perf/Documentation/perf-trace.txt	modified	+26	−1	View file
tools/perf/Makefile	modified	+1	−3	View file
tools/perf/builtin-annotate.c	modified	+23	−43	View file
tools/perf/builtin-buildid-list.c	modified	+2	−2	View file
tools/perf/builtin-diff.c	added	+248	−0	View file
tools/perf/builtin-kmem.c	modified	+26	−38	View file
tools/perf/builtin-probe.c	modified	+78	−63	View file
tools/perf/builtin-record.c	modified	+93	−48	View file
tools/perf/builtin-report.c	modified	+59	−664	View file
tools/perf/builtin-sched.c	modified	+50	−43	View file
tools/perf/builtin-timechart.c	modified	+24	−35	View file
tools/perf/builtin-top.c	modified	+27	−18	View file
tools/perf/builtin-trace.c	modified	+306	−43	View file
tools/perf/builtin.h	modified	+1	−0	View file
tools/perf/command-list.txt	modified	+1	−0	View file
tools/perf/perf.c	modified	+1	−0	View file
tools/perf/scripts/perl/bin/check-perf-trace-report	modified	+1	−0	View file
tools/perf/scripts/perl/bin/rw-by-file-report	modified	+3	−1	View file
tools/perf/scripts/perl/bin/rw-by-pid-report	modified	+1	−0	View file
tools/perf/scripts/perl/bin/wakeup-latency-report	modified	+1	−0	View file
tools/perf/scripts/perl/bin/workqueue-stats-report	modified	+1	−0	View file
tools/perf/scripts/perl/rw-by-file.pl	modified	+3	−2	View file
tools/perf/util/data_map.c	modified	+53	−43	View file
tools/perf/util/data_map.h	deleted	+0	−29	View before deletion
tools/perf/util/event.c	modified	+109	−33	View file
tools/perf/util/event.h	modified	+21	−15	View file
tools/perf/util/header.c	modified	+1	−1	View file
tools/perf/util/hist.c	modified	+489	−29	View file
tools/perf/util/hist.h	modified	+16	−39	View file
tools/perf/util/map.c	modified	+12	−6	View file
tools/perf/util/probe-event.c	modified	+141	−66	View file
tools/perf/util/probe-event.h	modified	+7	−4	View file
tools/perf/util/probe-finder.c	modified	+1	−3	View file
tools/perf/util/probe-finder.h	modified	+3	−0	View file
tools/perf/util/session.c	modified	+77	−7	View file
tools/perf/util/session.h	modified	+45	−0	View file
tools/perf/util/sort.c	modified	+26	−0	View file
tools/perf/util/sort.h	modified	+10	−2	View file
tools/perf/util/string.c	modified	+25	−0	View file
tools/perf/util/string.h	modified	+2	−0	View file
tools/perf/util/strlist.c	modified	+3	−3	View file
tools/perf/util/strlist.h	modified	+40	−1	View file
tools/perf/util/symbol.c	modified	+87	−57	View file
tools/perf/util/symbol.h	modified	+24	−10	View file
tools/perf/util/thread.c	modified	+12	−25	View file
tools/perf/util/thread.h	modified	+8	−8	View file
tools/perf/util/trace-event-perl.c	modified	+31	−11	View file
tools/perf/util/trace-event.h	modified	+1	−1	View file

Only the first 600 diff lines are shown. Download the complete patch.

include/linux/perf_event.h

View file

diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
index da7bdc2..c66b34f 100644
--- a/include/linux/perf_event.h
+++ b/include/linux/perf_event.h
@@ -211,17 +211,11 @@ struct perf_event_attr {
 		__u32		wakeup_watermark; /* bytes before wakeup   */
 	};
 
-	struct { /* Hardware breakpoint info */
-		__u64		bp_addr;
-		__u32		bp_type;
-		__u32		bp_len;
-		__u64		__bp_reserved_1;
-		__u64		__bp_reserved_2;
-	};
-
 	__u32			__reserved_2;
 
-	__u64			__reserved_3;
+	__u64			bp_addr;
+	__u32			bp_type;
+	__u32			bp_len;
 };
 
 /*

kernel/perf_event.c

View file

diff --git a/kernel/perf_event.c b/kernel/perf_event.c
index 9052d6c..8ab8698 100644
--- a/kernel/perf_event.c
+++ b/kernel/perf_event.c
@@ -782,6 +782,9 @@ static void __perf_install_in_context(void *info)
 
 	add_event_to_ctx(event, ctx);
 
+	if (event->cpu != -1 && event->cpu != smp_processor_id())
+		goto unlock;
+
 	/*
 	 * Don't put the event on if it is disabled or if
 	 * it is in a group and the group isn't on.
@@ -925,6 +928,9 @@ static void __perf_event_enable(void *info)
 		goto unlock;
 	__perf_event_mark_enabled(event, ctx);
 
+	if (event->cpu != -1 && event->cpu != smp_processor_id())
+		goto unlock;
+
 	/*
 	 * If the event is in a group and isn't the group leader,
 	 * then don't put it on unless the group is on.
@@ -1595,15 +1601,12 @@ static struct perf_event_context *find_get_context(pid_t pid, int cpu)
 	unsigned long flags;
 	int err;
 
-	/*
-	 * If cpu is not a wildcard then this is a percpu event:
-	 */
-	if (cpu != -1) {
+	if (pid == -1 && cpu != -1) {
 		/* Must be root to operate on a CPU event: */
 		if (perf_paranoid_cpu() && !capable(CAP_SYS_ADMIN))
 			return ERR_PTR(-EACCES);
 
-		if (cpu < 0 || cpu > num_possible_cpus())
+		if (cpu < 0 || cpu >= nr_cpumask_bits)
 			return ERR_PTR(-EINVAL);
 
 		/*
@@ -4564,7 +4567,7 @@ static int perf_copy_attr(struct perf_event_attr __user *uattr,
 	if (attr->type >= PERF_TYPE_MAX)
 		return -EINVAL;
 
-	if (attr->__reserved_1 || attr->__reserved_2 || attr->__reserved_3)
+	if (attr->__reserved_1 || attr->__reserved_2)
 		return -EINVAL;
 
 	if (attr->sample_type & ~(PERF_SAMPLE_MAX-1))

tools/perf/Documentation/perf-diff.txt

View file

diff --git a/tools/perf/Documentation/perf-diff.txt b/tools/perf/Documentation/perf-diff.txt
new file mode 100644
index 0000000..8974e20
--- /dev/null
+++ b/tools/perf/Documentation/perf-diff.txt
@@ -0,0 +1,55 @@
+perf-diff(1)
+==============
+
+NAME
+----
+perf-diff - Read two perf.data files and display the differential profile
+
+SYNOPSIS
+--------
+[verse]
+'perf diff' [oldfile] [newfile]
+
+DESCRIPTION
+-----------
+This command displays the performance difference amongst two perf.data files
+captured via perf record.
+
+If no parameters are passed it will assume perf.data.old and perf.data.
+
+OPTIONS
+-------
+-d::
+--dsos=::
+	Only consider symbols in these dsos. CSV that understands
+	file://filename entries.
+
+-C::
+--comms=::
+	Only consider symbols in these comms. CSV that understands
+	file://filename entries.
+
+-S::
+--symbols=::
+	Only consider these symbols. CSV that understands
+	file://filename entries.
+
+-s::
+--sort=::
+	Sort by key(s): pid, comm, dso, symbol.
+
+-t::
+--field-separator=::
+
+	Use a special separator character and don't pad with spaces, replacing
+	all occurances of this separator in symbol names (and other output)
+	with a '.' character, that thus it's the only non valid separator.
+
+-v::
+--verbose::
+	Be verbose, for instance, show the raw counts in addition to the
+	diff.
+
+SEE ALSO
+--------
+linkperf:perf-record[1]

tools/perf/Documentation/perf-probe.txt

View file

diff --git a/tools/perf/Documentation/perf-probe.txt b/tools/perf/Documentation/perf-probe.txt
index 8fa6bf9..250e391 100644
--- a/tools/perf/Documentation/perf-probe.txt
+++ b/tools/perf/Documentation/perf-probe.txt
@@ -49,8 +49,9 @@ PROBE SYNTAX
 ------------
 Probe points are defined by following syntax.
 
- "FUNC[+OFFS|:RLN|%return][@SRC]|SRC:ALN [ARG ...]"
+ "[EVENT=]FUNC[+OFFS|:RLN|%return][@SRC]|SRC:ALN [ARG ...]"
 
+'EVENT' specifies the name of new event, if omitted, it will be set the name of the probed function. Currently, event group name is set as 'probe'.
 'FUNC' specifies a probed function name, and it may have one of the following options; '+OFFS' is the offset from function entry address in bytes, 'RLN' is the relative-line number from function entry line, and '%return' means that it probes function return. In addition, 'SRC' specifies a source file which has that function.
 It is also possible to specify a probe point by the source line number by using 'SRC:ALN' syntax, where 'SRC' is the source file path and 'ALN' is the line number.
 'ARG' specifies the arguments of this probe point. You can use the name of local variable, or kprobe-tracer argument format (e.g. $retval, %ax, etc).

tools/perf/Documentation/perf-report.txt

View file

diff --git a/tools/perf/Documentation/perf-report.txt b/tools/perf/Documentation/perf-report.txt
index 9dccb18..abfabe9 100644
--- a/tools/perf/Documentation/perf-report.txt
+++ b/tools/perf/Documentation/perf-report.txt
@@ -39,6 +39,10 @@ OPTIONS
 	Only consider these symbols. CSV that understands
 	file://filename entries.
 
+-s::
+--sort=::
+	Sort by key(s): pid, comm, dso, symbol, parent.
+
 -w::
 --field-width=::
 	Force each column width to the provided list, for large terminal

tools/perf/Documentation/perf-trace.txt

View file

diff --git a/tools/perf/Documentation/perf-trace.txt b/tools/perf/Documentation/perf-trace.txt
index 07065ef..60e5900 100644
--- a/tools/perf/Documentation/perf-trace.txt
+++ b/tools/perf/Documentation/perf-trace.txt
@@ -8,18 +8,43 @@ perf-trace - Read perf.data (created by perf record) and display trace output
 SYNOPSIS
 --------
 [verse]
-'perf trace' [-i <file> | --input=file] symbol_name
+'perf trace' {record <script> | report <script> [args] }
 
 DESCRIPTION
 -----------
 This command reads the input file and displays the trace recorded.
 
+There are several variants of perf trace:
+
+  'perf trace' to see a detailed trace of the workload that was
+  recorded.
+
+  'perf trace record <script>' to record the events required for 'perf
+  trace report'.  <script> is the name displayed in the output of
+  'perf trace --list' i.e. the actual script name minus any language
+  extension.
+
+  'perf trace report <script>' to run and display the results of
+  <script>.  <script> is the name displayed in the output of 'perf
+  trace --list' i.e. the actual script name minus any language
+  extension.  The perf.data output from a previous run of 'perf trace
+  record <script>' is used and should be present for this command to
+  succeed.
+
 OPTIONS
 -------
 -D::
 --dump-raw-trace=::
         Display verbose dump of the trace data.
 
+-L::
+--Latency=::
+        Show latency attributes (irqs/preemption disabled, etc).
+
+-l::
+--list=::
+        Display a list of available trace scripts.
+
 -s::
 --script=::
         Process trace data with the given script ([lang]:script[.ext]).

tools/perf/Makefile

View file

diff --git a/tools/perf/Makefile b/tools/perf/Makefile
index 4069996..7814dbb 100644
--- a/tools/perf/Makefile
+++ b/tools/perf/Makefile
@@ -370,7 +370,6 @@ LIB_H += util/values.h
 LIB_H += util/sort.h
 LIB_H += util/hist.h
 LIB_H += util/thread.h
-LIB_H += util/data_map.h
 LIB_H += util/probe-finder.h
 LIB_H += util/probe-event.h
 
@@ -428,6 +427,7 @@ BUILTIN_OBJS += bench/sched-messaging.o
 BUILTIN_OBJS += bench/sched-pipe.o
 BUILTIN_OBJS += bench/mem-memcpy.o
 
+BUILTIN_OBJS += builtin-diff.o
 BUILTIN_OBJS += builtin-help.o
 BUILTIN_OBJS += builtin-sched.o
 BUILTIN_OBJS += builtin-buildid-list.o
@@ -996,8 +996,6 @@ install: all
 	$(INSTALL) scripts/perl/Perf-Trace-Util/lib/Perf/Trace/* -t '$(DESTDIR_SQ)$(perfexec_instdir_SQ)/scripts/perl/Perf-Trace-Util/lib/Perf/Trace'
 	$(INSTALL) scripts/perl/*.pl -t '$(DESTDIR_SQ)$(perfexec_instdir_SQ)/scripts/perl'
 	$(INSTALL) scripts/perl/bin/* -t '$(DESTDIR_SQ)$(perfexec_instdir_SQ)/scripts/perl/bin'
-	$(INSTALL) scripts/perl/Perf-Trace-Util/Makefile.PL -t '$(DESTDIR_SQ)$(perfexec_instdir_SQ)/scripts/perl/Perf-Trace-Util'
-	$(INSTALL) scripts/perl/Perf-Trace-Util/README -t '$(DESTDIR_SQ)$(perfexec_instdir_SQ)/scripts/perl/Perf-Trace-Util'
 ifdef BUILT_INS
 	$(INSTALL) -d -m 755 '$(DESTDIR_SQ)$(perfexec_instdir_SQ)'
 	$(INSTALL) $(BUILT_INS) '$(DESTDIR_SQ)$(perfexec_instdir_SQ)'

tools/perf/builtin-annotate.c

View file

diff --git a/tools/perf/builtin-annotate.c b/tools/perf/builtin-annotate.c
index 21a78d3..593ff25 100644
--- a/tools/perf/builtin-annotate.c
+++ b/tools/perf/builtin-annotate.c
@@ -26,7 +26,6 @@
 #include "util/sort.h"
 #include "util/hist.h"
 #include "util/session.h"
-#include "util/data_map.h"
 
 static char		const *input_name = "perf.data";
 
@@ -52,11 +51,6 @@ struct sym_priv {
 	struct sym_ext	*ext;
 };
 
-static struct symbol_conf symbol_conf = {
-	.priv_size	  = sizeof(struct sym_priv),
-	.try_vmlinux_path = true,
-};
-
 static const char *sym_hist_filter;
 
 static int symbol_filter(struct map *map __used, struct symbol *sym)
@@ -122,30 +116,32 @@ static void hist_hit(struct hist_entry *he, u64 ip)
 			h->ip[offset]);
 }
 
-static int hist_entry__add(struct addr_location *al, u64 count)
+static int perf_session__add_hist_entry(struct perf_session *self,
+					struct addr_location *al, u64 count)
 {
 	bool hit;
-	struct hist_entry *he = __hist_entry__add(al, NULL, count, &hit);
+	struct hist_entry *he = __perf_session__add_hist_entry(self, al, NULL,
+							       count, &hit);
 	if (he == NULL)
 		return -ENOMEM;
 	hist_hit(he, al->addr);
 	return 0;
 }
 
-static int process_sample_event(event_t *event)
+static int process_sample_event(event_t *event, struct perf_session *session)
 {
 	struct addr_location al;
 
 	dump_printf("(IP, %d): %d: %p\n", event->header.misc,
 		    event->ip.pid, (void *)(long)event->ip.ip);
 
-	if (event__preprocess_sample(event, &al, symbol_filter) < 0) {
+	if (event__preprocess_sample(event, session, &al, symbol_filter) < 0) {
 		fprintf(stderr, "problem processing %d event, skipping it.\n",
 			event->header.type);
 		return -1;
 	}
 
-	if (hist_entry__add(&al, 1)) {
+	if (!al.filtered && perf_session__add_hist_entry(session, &al, 1)) {
 		fprintf(stderr, "problem incrementing symbol count, "
 				"skipping event\n");
 		return -1;
@@ -429,11 +425,11 @@ static void annotate_sym(struct hist_entry *he)
 		free_source_line(he, len);
 }
 
-static void find_annotations(void)
+static void perf_session__find_annotations(struct perf_session *self)
 {
 	struct rb_node *nd;
 
-	for (nd = rb_first(&output_hists); nd; nd = rb_next(nd)) {
+	for (nd = rb_first(&self->hists); nd; nd = rb_next(nd)) {
 		struct hist_entry *he = rb_entry(nd, struct hist_entry, rb_node);
 		struct sym_priv *priv;
 
@@ -454,7 +450,7 @@ static void find_annotations(void)
 	}
 }
 
-static struct perf_file_handler file_handler = {
+static struct perf_event_ops event_ops = {
 	.process_sample_event	= process_sample_event,
 	.process_mmap_event	= event__process_mmap,
 	.process_comm_event	= event__process_comm,
@@ -463,17 +459,14 @@ static struct perf_file_handler file_handler = {
 
 static int __cmd_annotate(void)
 {
-	struct perf_session *session = perf_session__new(input_name, O_RDONLY, force);
-	struct thread *idle;
 	int ret;
+	struct perf_session *session;
 
+	session = perf_session__new(input_name, O_RDONLY, force);
 	if (session == NULL)
 		return -ENOMEM;
 
-	idle = register_idle_thread();
-	register_perf_file_handler(&file_handler);
-
-	ret = perf_session__process_events(session, 0, &event__cwdlen, &event__cwd);
+	ret = perf_session__process_events(session, &event_ops);
 	if (ret)
 		goto out_delete;
 
@@ -483,15 +476,14 @@ static int __cmd_annotate(void)
 	}
 
 	if (verbose > 3)
-		threads__fprintf(stdout);
+		perf_session__fprintf(session, stdout);
 
 	if (verbose > 2)
 		dsos__fprintf(stdout);
 
-	collapse__resort();
-	output__resort(event__total[0]);
-
-	find_annotations();
+	perf_session__collapse_resort(session);
+	perf_session__output_resort(session, session->event_total[0]);
+	perf_session__find_annotations(session);
 out_delete:
 	perf_session__delete(session);
 
@@ -524,29 +516,17 @@ static const struct option options[] = {
 	OPT_END()
 };
 
-static void setup_sorting(void)
+int cmd_annotate(int argc, const char **argv, const char *prefix __used)
 {
-	char *tmp, *tok, *str = strdup(sort_order);
-
-	for (tok = strtok_r(str, ", ", &tmp);
-			tok; tok = strtok_r(NULL, ", ", &tmp)) {
-		if (sort_dimension__add(tok) < 0) {
-			error("Unknown --sort key: `%s'", tok);
-			usage_with_options(annotate_usage, options);
-		}
-	}
+	argc = parse_options(argc, argv, options, annotate_usage, 0);
 
-	free(str);
-}
+	symbol_conf.priv_size = sizeof(struct sym_priv);
+	symbol_conf.try_vmlinux_path = true;
 
-int cmd_annotate(int argc, const char **argv, const char *prefix __used)
-{
-	if (symbol__init(&symbol_conf) < 0)
+	if (symbol__init() < 0)
 		return -1;
 
-	argc = parse_options(argc, argv, options, annotate_usage, 0);
-
-	setup_sorting();
+	setup_sorting(annotate_usage, options);
 
 	if (argc) {
 		/*

tools/perf/builtin-buildid-list.c

View file

diff --git a/tools/perf/builtin-buildid-list.c b/tools/perf/builtin-buildid-list.c
index bfd16a1..e693e67 100644
--- a/tools/perf/builtin-buildid-list.c
+++ b/tools/perf/builtin-buildid-list.c
@@ -9,7 +9,6 @@
 #include "builtin.h"
 #include "perf.h"
 #include "util/cache.h"
-#include "util/data_map.h"
 #include "util/debug.h"
 #include "util/parse-options.h"
 #include "util/session.h"
@@ -55,8 +54,9 @@ static int perf_file_section__process_buildids(struct perf_file_section *self,
 static int __cmd_buildid_list(void)
 {
 	int err = -1;
-	struct perf_session *session = perf_session__new(input_name, O_RDONLY, force);
+	struct perf_session *session;
 
+	session = perf_session__new(input_name, O_RDONLY, force);
 	if (session == NULL)
 		return -1;
 

tools/perf/builtin-diff.c

View file

diff --git a/tools/perf/builtin-diff.c b/tools/perf/builtin-diff.c
new file mode 100644
index 0000000..4d33b55
--- /dev/null
+++ b/tools/perf/builtin-diff.c
@@ -0,0 +1,248 @@
+/*
+ * builtin-diff.c
+ *
+ * Builtin diff command: Analyze two perf.data input files, look up and read
+ * DSOs and symbol information, sort them and produce a diff.
+ */
+#include "builtin.h"
+
+#include "util/debug.h"
+#include "util/event.h"
+#include "util/hist.h"
+#include "util/session.h"
+#include "util/sort.h"
+#include "util/symbol.h"
+#include "util/util.h"
+
+#include <stdlib.h>
+
+static char const *input_old = "perf.data.old",
+		  *input_new = "perf.data";
+static char	  diff__default_sort_order[] = "dso,symbol";
+static int  force;
+static bool show_displacement;
+
+static int perf_session__add_hist_entry(struct perf_session *self,
+					struct addr_location *al, u64 count)
+{
+	bool hit;
+	struct hist_entry *he = __perf_session__add_hist_entry(self, al, NULL,
+							       count, &hit);
+	if (he == NULL)
+		return -ENOMEM;
+
+	if (hit)
+		he->count += count;
+
+	return 0;
+}
+
+static int diff__process_sample_event(event_t *event, struct perf_session *session)
+{
+	struct addr_location al;
+	struct sample_data data = { .period = 1, };
+
+	dump_printf("(IP, %d): %d: %p\n", event->header.misc,
+		    event->ip.pid, (void *)(long)event->ip.ip);
+
+	if (event__preprocess_sample(event, session, &al, NULL) < 0) {
+		pr_warning("problem processing %d event, skipping it.\n",
+			   event->header.type);
+		return -1;
+	}
+
+	if (al.filtered)
+		return 0;
+
+	event__parse_sample(event, session->sample_type, &data);
+
+	if (al.sym && perf_session__add_hist_entry(session, &al, data.period)) {
+		pr_warning("problem incrementing symbol count, skipping event\n");
+		return -1;
+	}
+
+	session->events_stats.total += data.period;
+	return 0;
+}
+
+static struct perf_event_ops event_ops = {
+	.process_sample_event = diff__process_sample_event,
+	.process_mmap_event   = event__process_mmap,
+	.process_comm_event   = event__process_comm,
+	.process_exit_event   = event__process_task,
+	.process_fork_event   = event__process_task,
+	.process_lost_event   = event__process_lost,
+};
+
+static void perf_session__insert_hist_entry_by_name(struct rb_root *root,
+						    struct hist_entry *he)
+{
+	struct rb_node **p = &root->rb_node;
+	struct rb_node *parent = NULL;
+	struct hist_entry *iter;
+
+	while (*p != NULL) {
+		int cmp;
+		parent = *p;
+		iter = rb_entry(parent, struct hist_entry, rb_node);
+
+		cmp = strcmp(he->map->dso->name, iter->map->dso->name);
+		if (cmp > 0)
+			p = &(*p)->rb_left;
+		else if (cmp < 0)
+			p = &(*p)->rb_right;
+		else {
+			cmp = strcmp(he->sym->name, iter->sym->name);
+			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, root);
+}
+
+static void perf_session__resort_by_name(struct perf_session *self)
+{
+	unsigned long position = 1;
+	struct rb_root tmp = RB_ROOT;
+	struct rb_node *next = rb_first(&self->hists);
+
+	while (next != NULL) {
+		struct hist_entry *n = rb_entry(next, struct hist_entry, rb_node);
+
+		next = rb_next(&n->rb_node);
+		rb_erase(&n->rb_node, &self->hists);
+		n->position = position++;
+		perf_session__insert_hist_entry_by_name(&tmp, n);
+	}
+
+	self->hists = tmp;
+}
+
+static struct hist_entry *
+perf_session__find_hist_entry_by_name(struct perf_session *self,
+				      struct hist_entry *he)
+{
+	struct rb_node *n = self->hists.rb_node;
+
+	while (n) {
+		struct hist_entry *iter = rb_entry(n, struct hist_entry, rb_node);
+		int cmp = strcmp(he->map->dso->name, iter->map->dso->name);
+
+		if (cmp > 0)
+			n = n->rb_left;
+		else if (cmp < 0)
+			n = n->rb_right;
+		else {
+			cmp = strcmp(he->sym->name, iter->sym->name);
+			if (cmp > 0)
+				n = n->rb_left;
+			else if (cmp < 0)
+				n = n->rb_right;
+			else
+				return iter;
+		}
+	}
+
+	return NULL;
+}
+
+static void perf_session__match_hists(struct perf_session *old_session,
+				      struct perf_session *new_session)
+{
+	struct rb_node *nd;
+
+	perf_session__resort_by_name(old_session);
+
+	for (nd = rb_first(&new_session->hists); nd; nd = rb_next(nd)) {
+		struct hist_entry *pos = rb_entry(nd, struct hist_entry, rb_node);
+		pos->pair = perf_session__find_hist_entry_by_name(old_session, pos);
+	}
+}