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Date: Mon, 20 Feb 2017 10:33:20 +0100
From: Jan Stancek <jstancek@...hat.com>
To: linux-kernel@...r.kernel.org
Cc: peterz@...radead.org, mingo@...hat.com, acme@...nel.org,
alexander.shishkin@...ux.intel.com, jolsa@...nel.org,
mhiramat@...nel.org, jstancek@...hat.com
Subject: [PATCH v4 3/3] perf: Replace _SC_NPROCESSORS_CONF with max_present_cpu in cpu_topology_map
There are 2 problems wrt. cpu_topology_map on systems with sparse CPUs:
1. offline/absent CPUs will have their socket_id and core_id set to -1
which triggers:
"socket_id number is too big.You may need to upgrade the perf tool."
2. size of cpu_topology_map (perf_env.cpu[]) is allocated based on
_SC_NPROCESSORS_CONF, but can be indexed with CPU ids going above.
Users of perf_env.cpu[] are using CPU id as index. This can lead
to read beyond what was allocated:
==19991== Invalid read of size 4
==19991== at 0x490CEB: check_cpu_topology (topology.c:69)
==19991== by 0x490CEB: test_session_topology (topology.c:106)
...
For example:
_SC_NPROCESSORS_CONF == 16
available: 2 nodes (0-1)
node 0 cpus: 0 6 8 10 16 22 24 26
node 0 size: 12004 MB
node 0 free: 9470 MB
node 1 cpus: 1 7 9 11 23 25 27
node 1 size: 12093 MB
node 1 free: 9406 MB
node distances:
node 0 1
0: 10 20
1: 20 10
This patch changes HEADER_NRCPUS.nr_cpus_available from _SC_NPROCESSORS_CONF
to max_present_cpu and updates any user of cpu_topology_map to iterate
with nr_cpus_avail. As consequence HEADER_CPU_TOPOLOGY core_id and
socket_id lists get longer, but maintain compatibility with pre-patch
state - index to cpu_topology_map is CPU id.
# ./perf test 36 -v
36: Session topology :
--- start ---
test child forked, pid 22211
templ file: /tmp/perf-test-gmdX5i
CPU 0, core 0, socket 0
CPU 1, core 0, socket 1
CPU 6, core 10, socket 0
CPU 7, core 10, socket 1
CPU 8, core 1, socket 0
CPU 9, core 1, socket 1
CPU 10, core 9, socket 0
CPU 11, core 9, socket 1
CPU 16, core 0, socket 0
CPU 22, core 10, socket 0
CPU 23, core 10, socket 1
CPU 24, core 1, socket 0
CPU 25, core 1, socket 1
CPU 26, core 9, socket 0
CPU 27, core 9, socket 1
test child finished with 0
---- end ----
Session topology: Ok
Signed-off-by: Jan Stancek <jstancek@...hat.com>
---
tools/perf/builtin-stat.c | 2 +-
tools/perf/tests/topology.c | 4 +++-
tools/perf/util/env.c | 2 +-
tools/perf/util/header.c | 20 +++++++++-----------
4 files changed, 14 insertions(+), 14 deletions(-)
diff --git a/tools/perf/builtin-stat.c b/tools/perf/builtin-stat.c
index a02f2e965628..9e2be1c52fbd 100644
--- a/tools/perf/builtin-stat.c
+++ b/tools/perf/builtin-stat.c
@@ -1765,7 +1765,7 @@ static inline int perf_env__get_cpu(struct perf_env *env, struct cpu_map *map, i
cpu = map->map[idx];
- if (cpu >= env->nr_cpus_online)
+ if (cpu >= env->nr_cpus_avail)
return -1;
return cpu;
diff --git a/tools/perf/tests/topology.c b/tools/perf/tests/topology.c
index 98fe69ac553c..803f893550d6 100644
--- a/tools/perf/tests/topology.c
+++ b/tools/perf/tests/topology.c
@@ -65,7 +65,9 @@ static int check_cpu_topology(char *path, struct cpu_map *map)
session = perf_session__new(&file, false, NULL);
TEST_ASSERT_VAL("can't get session", session);
- for (i = 0; i < session->header.env.nr_cpus_online; i++) {
+ for (i = 0; i < session->header.env.nr_cpus_avail; i++) {
+ if (!cpu_map__has(map, i))
+ continue;
pr_debug("CPU %d, core %d, socket %d\n", i,
session->header.env.cpu[i].core_id,
session->header.env.cpu[i].socket_id);
diff --git a/tools/perf/util/env.c b/tools/perf/util/env.c
index bb964e86b09d..075fc77286bf 100644
--- a/tools/perf/util/env.c
+++ b/tools/perf/util/env.c
@@ -66,7 +66,7 @@ int perf_env__read_cpu_topology_map(struct perf_env *env)
return 0;
if (env->nr_cpus_avail == 0)
- env->nr_cpus_avail = sysconf(_SC_NPROCESSORS_CONF);
+ env->nr_cpus_avail = cpu__max_present_cpu();
nr_cpus = env->nr_cpus_avail;
if (nr_cpus == -1)
diff --git a/tools/perf/util/header.c b/tools/perf/util/header.c
index ca0f12fb5fd3..e97cbf78ef21 100644
--- a/tools/perf/util/header.c
+++ b/tools/perf/util/header.c
@@ -293,11 +293,7 @@ static int write_nrcpus(int fd, struct perf_header *h __maybe_unused,
u32 nrc, nra;
int ret;
- nr = sysconf(_SC_NPROCESSORS_CONF);
- if (nr < 0)
- return -1;
-
- nrc = (u32)(nr & UINT_MAX);
+ nrc = cpu__max_present_cpu();
nr = sysconf(_SC_NPROCESSORS_ONLN);
if (nr < 0)
@@ -511,9 +507,7 @@ static struct cpu_topo *build_cpu_topology(void)
int ret = -1;
struct cpu_map *map;
- ncpus = sysconf(_SC_NPROCESSORS_CONF);
- if (ncpus < 0)
- return NULL;
+ ncpus = cpu__max_present_cpu();
/* build online CPU map */
map = cpu_map__new(NULL);
@@ -1137,7 +1131,7 @@ static void print_cpu_topology(struct perf_header *ph, int fd __maybe_unused,
{
int nr, i;
char *str;
- int cpu_nr = ph->env.nr_cpus_online;
+ int cpu_nr = ph->env.nr_cpus_avail;
nr = ph->env.nr_sibling_cores;
str = ph->env.sibling_cores;
@@ -1792,7 +1786,7 @@ static int process_cpu_topology(struct perf_file_section *section,
u32 nr, i;
char *str;
struct strbuf sb;
- int cpu_nr = ph->env.nr_cpus_online;
+ int cpu_nr = ph->env.nr_cpus_avail;
u64 size = 0;
ph->env.cpu = calloc(cpu_nr, sizeof(*ph->env.cpu));
@@ -1873,7 +1867,11 @@ static int process_cpu_topology(struct perf_file_section *section,
if (ph->needs_swap)
nr = bswap_32(nr);
- if (nr > (u32)cpu_nr) {
+ /*
+ * Offline/absent CPUs have their socket_id set to -1,
+ * don't treat that as error.
+ */
+ if (nr != (u32)-1 && nr > (u32)cpu_nr) {
pr_debug("socket_id number is too big."
"You may need to upgrade the perf tool.\n");
goto free_cpu;
--
1.8.3.1
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