perf/core improvements:

User visible:
 
 o Support handling complete branch stacks as histograms (Andi Kleen)
 
 Infrastructure:
 
 o Prep work for supporting per-pkg and snapshot counters in 'perf stat' (Jiri Olsa)
 
 Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
 -----BEGIN PGP SIGNATURE-----
 Version: GnuPG v1
 
 iQEcBAABAgAGBQJUfPO7AAoJEBpxZoYYoA71TvEIAKyJODdEj7oVjYMqehGZfLPU
 mR54xXWVOWaHWrsl/E7SiRudue7IdTnAzabQjq2VnxbDG7Y8oSJ8uYwHhAu9Sxtr
 WYGa+pAdnn5fwt/xm9Dqd0BuLI3DFB2t0aRvOJ9odPEBjHkLwgizFaACuKhWjSN7
 LiwUTxVxQn8z+M/xgmH4jKuFH+QG7LHVqNHgjrPOX23J8AEDxGzXEIws8vymIrzZ
 pYAHtQ5s6yNU1JOS04gX8DFcGHOZnkcgVyIdD9f/QNMXSAZB/GJBtYrvprzl0i8O
 AiyTKYMrK1Il5nJkESsjunNkWfnEwJw95BEwlVPIKsgPW3wNaBoWfUpfkFK7T+k=
 =V1km
 -----END PGP SIGNATURE-----

Merge tag 'perf-core-for-mingo-2' of git://git.kernel.org/pub/scm/linux/kernel/git/acme/linux into perf/core

Pull perf/core improvements from Arnaldo Carvalho de Melo:

User visible changes:

  - Support handling complete branch stacks as histograms (Andi Kleen)

Infrastructure changes:

  - Prep work for supporting per-pkg and snapshot counters in 'perf stat' (Jiri Olsa)

Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>

tools/perf/Documentation/perf-report.txt

@@ -159,7 +159,7 @@ OPTIONS
 --dump-raw-trace::
         Dump raw trace in ASCII.
 
--g [type,min[,limit],order[,key]]::
+-g [type,min[,limit],order[,key][,branch]]::
 --call-graph::
         Display call chains using type, min percent threshold, optional print
 	limit and order.
@@ -177,6 +177,11 @@ OPTIONS
 	- function: compare on functions
 	- address: compare on individual code addresses
 
+	branch can be:
+	- branch: include last branch information in callgraph
+	when available. Usually more convenient to use --branch-history
+	for this.
+
 	Default: fractal,0.5,callee,function.
 
 --children::
@@ -266,6 +271,11 @@ OPTIONS
 	branch stacks and it will automatically switch to the branch view mode,
 	unless --no-branch-stack is used.
 
+--branch-history::
+	Add the addresses of sampled taken branches to the callstack.
+	This allows to examine the path the program took to each sample.
+	The data collection must have used -b (or -j) and -g.
+
 --objdump=<path>::
         Path to objdump binary.
 

tools/perf/builtin-report.c

@@ -226,8 +226,9 @@ static int report__setup_sample_type(struct report *rep)
 			return -EINVAL;
 		}
 		if (symbol_conf.use_callchain) {
-			ui__error("Selected -g but no callchain data. Did "
-				    "you call 'perf record' without -g?\n");
+			ui__error("Selected -g or --branch-history but no "
+				  "callchain data. Did\n"
+				  "you call 'perf record' without -g?\n");
 			return -1;
 		}
 	} else if (!rep->dont_use_callchains &&
@@ -575,6 +576,7 @@ int cmd_report(int argc, const char **argv, const char *prefix __maybe_unused)
 	struct stat st;
 	bool has_br_stack = false;
 	int branch_mode = -1;
+	bool branch_call_mode = false;
 	char callchain_default_opt[] = "fractal,0.5,callee";
 	const char * const report_usage[] = {
 		"perf report [<options>]",
@@ -637,8 +639,8 @@ int cmd_report(int argc, const char **argv, const char *prefix __maybe_unused)
 		   "regex filter to identify parent, see: '--sort parent'"),
 	OPT_BOOLEAN('x', "exclude-other", &symbol_conf.exclude_other,
 		    "Only display entries with parent-match"),
-	OPT_CALLBACK_DEFAULT('g', "call-graph", &report, "output_type,min_percent[,print_limit],call_order",
-		     "Display callchains using output_type (graph, flat, fractal, or none) , min percent threshold, optional print limit, callchain order, key (function or address). "
+	OPT_CALLBACK_DEFAULT('g', "call-graph", &report, "output_type,min_percent[,print_limit],call_order[,branch]",
+		     "Display callchains using output_type (graph, flat, fractal, or none) , min percent threshold, optional print limit, callchain order, key (function or address), add branches. "
 		     "Default: fractal,0.5,callee,function", &report_parse_callchain_opt, callchain_default_opt),
 	OPT_BOOLEAN(0, "children", &symbol_conf.cumulate_callchain,
 		    "Accumulate callchains of children and show total overhead as well"),
@@ -684,7 +686,10 @@ int cmd_report(int argc, const char **argv, const char *prefix __maybe_unused)
 	OPT_BOOLEAN(0, "group", &symbol_conf.event_group,
 		    "Show event group information together"),
 	OPT_CALLBACK_NOOPT('b', "branch-stack", &branch_mode, "",
-		    "use branch records for histogram filling", parse_branch_mode),
+		    "use branch records for per branch histogram filling",
+		    parse_branch_mode),
+	OPT_BOOLEAN(0, "branch-history", &branch_call_mode,
+		    "add last branch records to call history"),
 	OPT_STRING(0, "objdump", &objdump_path, "path",
 		   "objdump binary to use for disassembly and annotations"),
 	OPT_BOOLEAN(0, "demangle", &symbol_conf.demangle,
@@ -745,10 +750,24 @@ repeat:
 	has_br_stack = perf_header__has_feat(&session->header,
 					     HEADER_BRANCH_STACK);
 
-	if ((branch_mode == -1 && has_br_stack) || branch_mode == 1) {
+	/*
+	 * Branch mode is a tristate:
+	 * -1 means default, so decide based on the file having branch data.
+	 * 0/1 means the user chose a mode.
+	 */
+	if (((branch_mode == -1 && has_br_stack) || branch_mode == 1) &&
+	    branch_call_mode == -1) {
 		sort__mode = SORT_MODE__BRANCH;
 		symbol_conf.cumulate_callchain = false;
 	}
+	if (branch_call_mode) {
+		callchain_param.key = CCKEY_ADDRESS;
+		callchain_param.branch_callstack = 1;
+		symbol_conf.use_callchain = true;
+		callchain_register_param(&callchain_param);
+		if (sort_order == NULL)
+			sort_order = "srcline,symbol,dso";
+	}
 
 	if (report.mem_mode) {
 		if (sort__mode == SORT_MODE__BRANCH) {

tools/perf/builtin-stat.c

@@ -388,20 +388,102 @@ static void update_shadow_stats(struct perf_evsel *counter, u64 *count)
 		update_stats(&runtime_itlb_cache_stats[0], count[0]);
 }
 
+static void zero_per_pkg(struct perf_evsel *counter)
+{
+	if (counter->per_pkg_mask)
+		memset(counter->per_pkg_mask, 0, MAX_NR_CPUS);
+}
+
+static int check_per_pkg(struct perf_evsel *counter, int cpu, bool *skip)
+{
+	unsigned long *mask = counter->per_pkg_mask;
+	struct cpu_map *cpus = perf_evsel__cpus(counter);
+	int s;
+
+	*skip = false;
+
+	if (!counter->per_pkg)
+		return 0;
+
+	if (cpu_map__empty(cpus))
+		return 0;
+
+	if (!mask) {
+		mask = zalloc(MAX_NR_CPUS);
+		if (!mask)
+			return -ENOMEM;
+
+		counter->per_pkg_mask = mask;
+	}
+
+	s = cpu_map__get_socket(cpus, cpu);
+	if (s < 0)
+		return -1;
+
+	*skip = test_and_set_bit(s, mask) == 1;
+	return 0;
+}
+
+static int read_cb(struct perf_evsel *evsel, int cpu, int thread __maybe_unused,
+		   struct perf_counts_values *count)
+{
+	struct perf_counts_values *aggr = &evsel->counts->aggr;
+	static struct perf_counts_values zero;
+	bool skip = false;
+
+	if (check_per_pkg(evsel, cpu, &skip)) {
+		pr_err("failed to read per-pkg counter\n");
+		return -1;
+	}
+
+	if (skip)
+		count = &zero;
+
+	switch (aggr_mode) {
+	case AGGR_CORE:
+	case AGGR_SOCKET:
+	case AGGR_NONE:
+		if (!evsel->snapshot)
+			perf_evsel__compute_deltas(evsel, cpu, count);
+		perf_counts_values__scale(count, scale, NULL);
+		evsel->counts->cpu[cpu] = *count;
+		update_shadow_stats(evsel, count->values);
+		break;
+	case AGGR_GLOBAL:
+		aggr->val += count->val;
+		if (scale) {
+			aggr->ena += count->ena;
+			aggr->run += count->run;
+		}
+	default:
+		break;
+	}
+
+	return 0;
+}
+
+static int read_counter(struct perf_evsel *counter);
+
 /*
  * Read out the results of a single counter:
  * aggregate counts across CPUs in system-wide mode
  */
 static int read_counter_aggr(struct perf_evsel *counter)
 {
+	struct perf_counts_values *aggr = &counter->counts->aggr;
 	struct perf_stat *ps = counter->priv;
 	u64 *count = counter->counts->aggr.values;
 	int i;
 
-	if (__perf_evsel__read(counter, perf_evsel__nr_cpus(counter),
-			       thread_map__nr(evsel_list->threads), scale) < 0)
+	aggr->val = aggr->ena = aggr->run = 0;
+
+	if (read_counter(counter))
 		return -1;
 
+	if (!counter->snapshot)
+		perf_evsel__compute_deltas(counter, -1, aggr);
+	perf_counts_values__scale(aggr, scale, &counter->counts->scaled);
+
 	for (i = 0; i < 3; i++)
 		update_stats(&ps->res_stats[i], count[i]);
 
@@ -424,16 +506,21 @@ static int read_counter_aggr(struct perf_evsel *counter)
  */
 static int read_counter(struct perf_evsel *counter)
 {
-	u64 *count;
-	int cpu;
+	int nthreads = thread_map__nr(evsel_list->threads);
+	int ncpus = perf_evsel__nr_cpus(counter);
+	int cpu, thread;
 
-	for (cpu = 0; cpu < perf_evsel__nr_cpus(counter); cpu++) {
-		if (__perf_evsel__read_on_cpu(counter, cpu, 0, scale) < 0)
-			return -1;
+	if (counter->system_wide)
+		nthreads = 1;
 
-		count = counter->counts->cpu[cpu].values;
+	if (counter->per_pkg)
+		zero_per_pkg(counter);
 
-		update_shadow_stats(counter, count);
+	for (thread = 0; thread < nthreads; thread++) {
+		for (cpu = 0; cpu < ncpus; cpu++) {
+			if (perf_evsel__read_cb(counter, cpu, thread, read_cb))
+				return -1;
+		}
 	}
 
 	return 0;

tools/perf/util/callchain.c

@@ -149,6 +149,10 @@ static int parse_callchain_sort_key(const char *value)
 		callchain_param.key = CCKEY_ADDRESS;
 		return 0;
 	}
+	if (!strncmp(value, "branch", strlen(value))) {
+		callchain_param.branch_callstack = 1;
+		return 0;
+	}
 	return -1;
 }
 

tools/perf/util/callchain.h

@@ -63,6 +63,7 @@ struct callchain_param {
 	sort_chain_func_t	sort;
 	enum chain_order	order;
 	enum chain_key		key;
+	bool			branch_callstack;
 };
 
 extern struct callchain_param callchain_param;

tools/perf/util/evsel.c

@@ -954,40 +954,6 @@ int __perf_evsel__read_on_cpu(struct perf_evsel *evsel,
 	return 0;
 }
 
-int __perf_evsel__read(struct perf_evsel *evsel,
-		       int ncpus, int nthreads, bool scale)
-{
-	size_t nv = scale ? 3 : 1;
-	int cpu, thread;
-	struct perf_counts_values *aggr = &evsel->counts->aggr, count;
-
-	if (evsel->system_wide)
-		nthreads = 1;
-
-	aggr->val = aggr->ena = aggr->run = 0;
-
-	for (cpu = 0; cpu < ncpus; cpu++) {
-		for (thread = 0; thread < nthreads; thread++) {
-			if (FD(evsel, cpu, thread) < 0)
-				continue;
-
-			if (readn(FD(evsel, cpu, thread),
-				  &count, nv * sizeof(u64)) < 0)
-				return -errno;
-
-			aggr->val += count.val;
-			if (scale) {
-				aggr->ena += count.ena;
-				aggr->run += count.run;
-			}
-		}
-	}
-
-	perf_evsel__compute_deltas(evsel, -1, aggr);
-	perf_counts_values__scale(aggr, scale, &evsel->counts->scaled);
-	return 0;
-}
-
 static int get_group_fd(struct perf_evsel *evsel, int cpu, int thread)
 {
 	struct perf_evsel *leader = evsel->leader;

tools/perf/util/evsel.h

@@ -93,6 +93,7 @@ struct perf_evsel {
 	bool			system_wide;
 	bool			tracking;
 	bool			per_pkg;
+	unsigned long		*per_pkg_mask;
 	/* parse modifier helper */
 	int			exclude_GH;
 	int			nr_members;
@@ -271,35 +272,6 @@ static inline int perf_evsel__read_on_cpu_scaled(struct perf_evsel *evsel,
 	return __perf_evsel__read_on_cpu(evsel, cpu, thread, true);
 }
 
-int __perf_evsel__read(struct perf_evsel *evsel, int ncpus, int nthreads,
-		       bool scale);
-
-/**
- * perf_evsel__read - Read the aggregate results on all CPUs
- *
- * @evsel - event selector to read value
- * @ncpus - Number of cpus affected, from zero
- * @nthreads - Number of threads affected, from zero
- */
-static inline int perf_evsel__read(struct perf_evsel *evsel,
-				    int ncpus, int nthreads)
-{
-	return __perf_evsel__read(evsel, ncpus, nthreads, false);
-}
-
-/**
- * perf_evsel__read_scaled - Read the aggregate results on all CPUs, scaled
- *
- * @evsel - event selector to read value
- * @ncpus - Number of cpus affected, from zero
- * @nthreads - Number of threads affected, from zero
- */
-static inline int perf_evsel__read_scaled(struct perf_evsel *evsel,
-					  int ncpus, int nthreads)
-{
-	return __perf_evsel__read(evsel, ncpus, nthreads, true);
-}
-
 int perf_evsel__parse_sample(struct perf_evsel *evsel, union perf_event *event,
 			     struct perf_sample *sample);
 

tools/perf/util/machine.c

@@ -12,6 +12,7 @@
 #include <stdbool.h>
 #include <symbol/kallsyms.h>
 #include "unwind.h"
+#include "linux/hash.h"
 
 static void dsos__init(struct dsos *dsos)
 {
@@ -1391,7 +1392,11 @@ static int add_callchain_ip(struct thread *thread,
 
 	al.filtered = 0;
 	al.sym = NULL;
-	thread__find_addr_location(thread, cpumode, MAP__FUNCTION,
+	if (cpumode == -1)
+		thread__find_cpumode_addr_location(thread, MAP__FUNCTION,
+						   ip, &al);
+	else
+		thread__find_addr_location(thread, cpumode, MAP__FUNCTION,
 				   ip, &al);
 	if (al.sym != NULL) {
 		if (sort__has_parent && !*parent &&
@@ -1427,8 +1432,50 @@ struct branch_info *sample__resolve_bstack(struct perf_sample *sample,
 	return bi;
 }
 
+#define CHASHSZ 127
+#define CHASHBITS 7
+#define NO_ENTRY 0xff
+
+#define PERF_MAX_BRANCH_DEPTH 127
+
+/* Remove loops. */
+static int remove_loops(struct branch_entry *l, int nr)
+{
+	int i, j, off;
+	unsigned char chash[CHASHSZ];
+
+	memset(chash, NO_ENTRY, sizeof(chash));
+
+	BUG_ON(PERF_MAX_BRANCH_DEPTH > 255);
+
+	for (i = 0; i < nr; i++) {
+		int h = hash_64(l[i].from, CHASHBITS) % CHASHSZ;
+
+		/* no collision handling for now */
+		if (chash[h] == NO_ENTRY) {
+			chash[h] = i;
+		} else if (l[chash[h]].from == l[i].from) {
+			bool is_loop = true;
+			/* check if it is a real loop */
+			off = 0;
+			for (j = chash[h]; j < i && i + off < nr; j++, off++)
+				if (l[j].from != l[i + off].from) {
+					is_loop = false;
+					break;
+				}
+			if (is_loop) {
+				memmove(l + i, l + i + off,
+					(nr - (i + off)) * sizeof(*l));
+				nr -= off;
+			}
+		}
+	}
+	return nr;
+}
+
 static int thread__resolve_callchain_sample(struct thread *thread,
 					     struct ip_callchain *chain,
+					     struct branch_stack *branch,
 					     struct symbol **parent,
 					     struct addr_location *root_al,
 					     int max_stack)
@@ -1438,22 +1485,82 @@ static int thread__resolve_callchain_sample(struct thread *thread,
 	int i;
 	int j;
 	int err;
-	int skip_idx __maybe_unused;
-
-	callchain_cursor_reset(&callchain_cursor);
-
-	if (chain->nr > PERF_MAX_STACK_DEPTH) {
-		pr_warning("corrupted callchain. skipping...\n");
-		return 0;
-	}
+	int skip_idx = -1;
+	int first_call = 0;
 
 	/*
 	 * Based on DWARF debug information, some architectures skip
 	 * a callchain entry saved by the kernel.
 	 */
-	skip_idx = arch_skip_callchain_idx(thread, chain);
+	if (chain->nr < PERF_MAX_STACK_DEPTH)
+		skip_idx = arch_skip_callchain_idx(thread, chain);
 
-	for (i = 0; i < chain_nr; i++) {
+	callchain_cursor_reset(&callchain_cursor);
+
+	/*
+	 * Add branches to call stack for easier browsing. This gives
+	 * more context for a sample than just the callers.
+	 *
+	 * This uses individual histograms of paths compared to the
+	 * aggregated histograms the normal LBR mode uses.
+	 *
+	 * Limitations for now:
+	 * - No extra filters
+	 * - No annotations (should annotate somehow)
+	 */
+
+	if (branch && callchain_param.branch_callstack) {
+		int nr = min(max_stack, (int)branch->nr);
+		struct branch_entry be[nr];
+
+		if (branch->nr > PERF_MAX_BRANCH_DEPTH) {
+			pr_warning("corrupted branch chain. skipping...\n");
+			goto check_calls;
+		}
+
+		for (i = 0; i < nr; i++) {
+			if (callchain_param.order == ORDER_CALLEE) {
+				be[i] = branch->entries[i];
+				/*
+				 * Check for overlap into the callchain.
+				 * The return address is one off compared to
+				 * the branch entry. To adjust for this
+				 * assume the calling instruction is not longer
+				 * than 8 bytes.
+				 */
+				if (i == skip_idx ||
+				    chain->ips[first_call] >= PERF_CONTEXT_MAX)
+					first_call++;
+				else if (be[i].from < chain->ips[first_call] &&
+				    be[i].from >= chain->ips[first_call] - 8)
+					first_call++;
+			} else
+				be[i] = branch->entries[branch->nr - i - 1];
+		}
+
+		nr = remove_loops(be, nr);
+
+		for (i = 0; i < nr; i++) {
+			err = add_callchain_ip(thread, parent, root_al,
+					       -1, be[i].to);
+			if (!err)
+				err = add_callchain_ip(thread, parent, root_al,
+						       -1, be[i].from);
+			if (err == -EINVAL)
+				break;
+			if (err)
+				return err;
+		}
+		chain_nr -= nr;
+	}
+
+check_calls:
+	if (chain->nr > PERF_MAX_STACK_DEPTH) {
+		pr_warning("corrupted callchain. skipping...\n");
+		return 0;
+	}
+
+	for (i = first_call; i < chain_nr; i++) {
 		u64 ip;
 
 		if (callchain_param.order == ORDER_CALLEE)
@@ -1517,6 +1624,7 @@ int thread__resolve_callchain(struct thread *thread,
 			      int max_stack)
 {
 	int ret = thread__resolve_callchain_sample(thread, sample->callchain,
+						   sample->branch_stack,
 						   parent, root_al, max_stack);
 	if (ret)
 		return ret;

tools/perf/util/symbol.h

@@ -102,7 +102,8 @@ struct symbol_conf {
 			demangle,
 			demangle_kernel,
 			filter_relative,
-			show_hist_headers;
+			show_hist_headers,
+			branch_callstack;
 	const char	*vmlinux_name,
 			*kallsyms_name,
 			*source_prefix,