perf report: Add 'cgroup' sort key

The cgroup sort key is to show cgroup membership of each task.
Currently it shows full path in the cgroupfs (not relative to the root
of cgroup namespace) since it'd be more intuitive IMHO.  Otherwise root
cgroup in different namespaces will all show same name - "/".

The cgroup sort key should come before cgroup_id otherwise
sort_dimension__add() will match it to cgroup_id as it only matches with
the given substring.

For example it will look like following.  Note that record patch adding
--all-cgroups patch will come later.

  $ perf record -a --namespace --all-cgroups  cgtest
  [ perf record: Woken up 1 times to write data ]
  [ perf record: Captured and wrote 0.208 MB perf.data (4090 samples) ]

  $ perf report -s cgroup_id,cgroup,pid
  ...
  # Overhead  cgroup id (dev/inode)  Cgroup          Pid:Command
  # ........  .....................  ..........  ...............
  #
      93.96%  0/0x0                  /                 0:swapper
       1.25%  3/0xeffffffb           /               278:looper0
       0.86%  3/0xf000015f           /sub/cgrp1      280:cgtest
       0.37%  3/0xf0000160           /sub/cgrp2      281:cgtest
       0.34%  3/0xf0000163           /sub/cgrp3      282:cgtest
       0.22%  3/0xeffffffb           /sub            278:looper0
       0.20%  3/0xeffffffb           /               280:cgtest
       0.15%  3/0xf0000163           /sub/cgrp3      285:looper3

Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lore.kernel.org/lkml/20200325124536.2800725-6-namhyung@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/Documentation/perf-report.txt

@@ -95,6 +95,7 @@ OPTIONS
 	abort cost. This is the global weight.
 	- local_weight: Local weight version of the weight above.
 	- cgroup_id: ID derived from cgroup namespace device and inode numbers.
+	- cgroup: cgroup pathname in the cgroupfs.
 	- transaction: Transaction abort flags.
 	- overhead: Overhead percentage of sample
 	- overhead_sys: Overhead percentage of sample running in system mode

tools/perf/util/hist.c

@@ -10,6 +10,7 @@
 #include "mem-events.h"
 #include "session.h"
 #include "namespaces.h"
+#include "cgroup.h"
 #include "sort.h"
 #include "units.h"
 #include "evlist.h"
@@ -194,6 +195,7 @@ void hists__calc_col_len(struct hists *hists, struct hist_entry *h)
 		hists__set_unres_dso_col_len(hists, HISTC_MEM_DADDR_DSO);
 	}
 
+	hists__new_col_len(hists, HISTC_CGROUP, 6);
 	hists__new_col_len(hists, HISTC_CGROUP_ID, 20);
 	hists__new_col_len(hists, HISTC_CPU, 3);
 	hists__new_col_len(hists, HISTC_SOCKET, 6);
@@ -222,6 +224,16 @@ void hists__calc_col_len(struct hists *hists, struct hist_entry *h)
 
 	if (h->trace_output)
 		hists__new_col_len(hists, HISTC_TRACE, strlen(h->trace_output));
+
+	if (h->cgroup) {
+		const char *cgrp_name = "unknown";
+		struct cgroup *cgrp = cgroup__find(h->ms.maps->machine->env,
+						   h->cgroup);
+		if (cgrp != NULL)
+			cgrp_name = cgrp->name;
+
+		hists__new_col_len(hists, HISTC_CGROUP, strlen(cgrp_name));
+	}
 }
 
 void hists__output_recalc_col_len(struct hists *hists, int max_rows)
@@ -691,6 +703,7 @@ __hists__add_entry(struct hists *hists,
 			.dev = ns ? ns->link_info[CGROUP_NS_INDEX].dev : 0,
 			.ino = ns ? ns->link_info[CGROUP_NS_INDEX].ino : 0,
 		},
+		.cgroup = sample->cgroup,
 		.ms = {
 			.maps	= al->maps,
 			.map	= al->map,

tools/perf/util/hist.h

@@ -38,6 +38,7 @@ enum hist_column {
 	HISTC_THREAD,
 	HISTC_COMM,
 	HISTC_CGROUP_ID,
+	HISTC_CGROUP,
 	HISTC_PARENT,
 	HISTC_CPU,
 	HISTC_SOCKET,

tools/perf/util/sort.c

@@ -12,6 +12,7 @@
 #include "cacheline.h"
 #include "comm.h"
 #include "map.h"
+#include "maps.h"
 #include "symbol.h"
 #include "map_symbol.h"
 #include "branch.h"
@@ -25,6 +26,8 @@
 #include "mem-events.h"
 #include "annotate.h"
 #include "time-utils.h"
+#include "cgroup.h"
+#include "machine.h"
 #include <linux/kernel.h>
 #include <linux/string.h>
 
@@ -634,6 +637,39 @@ struct sort_entry sort_cgroup_id = {
 	.se_width_idx	= HISTC_CGROUP_ID,
 };
 
+/* --sort cgroup */
+
+static int64_t
+sort__cgroup_cmp(struct hist_entry *left, struct hist_entry *right)
+{
+	return right->cgroup - left->cgroup;
+}
+
+static int hist_entry__cgroup_snprintf(struct hist_entry *he,
+				       char *bf, size_t size,
+				       unsigned int width __maybe_unused)
+{
+	const char *cgrp_name = "N/A";
+
+	if (he->cgroup) {
+		struct cgroup *cgrp = cgroup__find(he->ms.maps->machine->env,
+						   he->cgroup);
+		if (cgrp != NULL)
+			cgrp_name = cgrp->name;
+		else
+			cgrp_name = "unknown";
+	}
+
+	return repsep_snprintf(bf, size, "%s", cgrp_name);
+}
+
+struct sort_entry sort_cgroup = {
+	.se_header      = "Cgroup",
+	.se_cmp	        = sort__cgroup_cmp,
+	.se_snprintf    = hist_entry__cgroup_snprintf,
+	.se_width_idx	= HISTC_CGROUP,
+};
+
 /* --sort socket */
 
 static int64_t
@@ -1660,6 +1696,7 @@ static struct sort_dimension common_sort_dimensions[] = {
 	DIM(SORT_TRACE, "trace", sort_trace),
 	DIM(SORT_SYM_SIZE, "symbol_size", sort_sym_size),
 	DIM(SORT_DSO_SIZE, "dso_size", sort_dso_size),
+	DIM(SORT_CGROUP, "cgroup", sort_cgroup),
 	DIM(SORT_CGROUP_ID, "cgroup_id", sort_cgroup_id),
 	DIM(SORT_SYM_IPC_NULL, "ipc_null", sort_sym_ipc_null),
 	DIM(SORT_TIME, "time", sort_time),

tools/perf/util/sort.h

@@ -101,6 +101,7 @@ struct hist_entry {
 	struct thread		*thread;
 	struct comm		*comm;
 	struct namespace_id	cgroup_id;
+	u64			cgroup;
 	u64			ip;
 	u64			transaction;
 	s32			socket;
@@ -224,6 +225,7 @@ enum sort_type {
 	SORT_TRACE,
 	SORT_SYM_SIZE,
 	SORT_DSO_SIZE,
+	SORT_CGROUP,
 	SORT_CGROUP_ID,
 	SORT_SYM_IPC_NULL,
 	SORT_TIME,