Re: [PATCH] perf intel-pt: Fix 'CPU too large' error

[Liang, Kan]

On 1/7/2021 12:41 PM, Adrian Hunter wrote:

In some cases, the number of cpus (nr_cpus_online) is confused with the
maximum cpu number (nr_cpus_avail), which results in the error in the
example below:

Example on system with 8 cpus:

  Before:
    # echo 0 > /sys/devices/system/cpu/cpu2/online
    # ./perf record --kcore -e intel_pt// taskset --cpu-list 7 uname
    Linux
    [ perf record: Woken up 1 times to write data ]
    [ perf record: Captured and wrote 0.147 MB perf.data ]
    # ./perf script --itrace=e
    Requested CPU 7 too large. Consider raising MAX_NR_CPUS
    0x25908 [0x8]: failed to process type: 68 [Invalid argument]

  After:
    # ./perf script --itrace=e
    #

Fixes: 8c7274691f0d ("perf machine: Replace MAX_NR_CPUS with 
perf_env::nr_cpus_online")
Fixes: 7df4e36a4785 ("perf session: Replace MAX_NR_CPUS with 
perf_env::nr_cpus_online")
Cc: sta...@vger.kernel.org
Signed-off-by: Adrian Hunter <adrian.hun...@intel.com>

Tested-by: Kan Liang <kan.li...@linux.intel.com>

Thanks,
Kan

---
  tools/perf/util/machine.c | 4 ++--
  tools/perf/util/session.c | 2 +-
  2 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/tools/perf/util/machine.c b/tools/perf/util/machine.c
index 1ae32a81639c..46844599d25d 100644
--- a/tools/perf/util/machine.c
+++ b/tools/perf/util/machine.c
@@ -2977,7 +2977,7 @@ int machines__for_each_thread(struct machines *machines,

pid_t machine__get_current_tid(struct machine *machine, int cpu)

  {
-       int nr_cpus = min(machine->env->nr_cpus_online, MAX_NR_CPUS);
+       int nr_cpus = min(machine->env->nr_cpus_avail, MAX_NR_CPUS);

if (cpu < 0 || cpu >= nr_cpus || !machine->current_tid)

                return -1;
@@ -2989,7 +2989,7 @@ int machine__set_current_tid(struct machine *machine, int 
cpu, pid_t pid,
                             pid_t tid)
  {
        struct thread *thread;
-       int nr_cpus = min(machine->env->nr_cpus_online, MAX_NR_CPUS);
+       int nr_cpus = min(machine->env->nr_cpus_avail, MAX_NR_CPUS);

if (cpu < 0)

                return -EINVAL;
diff --git a/tools/perf/util/session.c b/tools/perf/util/session.c
index 3b3c50b12791..2777c2df7d87 100644
--- a/tools/perf/util/session.c
+++ b/tools/perf/util/session.c
@@ -2391,7 +2391,7 @@ int perf_session__cpu_bitmap(struct perf_session *session,
  {
        int i, err = -1;
        struct perf_cpu_map *map;
-       int nr_cpus = min(session->header.env.nr_cpus_online, MAX_NR_CPUS);
+       int nr_cpus = min(session->header.env.nr_cpus_avail, MAX_NR_CPUS);

for (i = 0; i < PERF_TYPE_MAX; ++i) {

                struct evsel *evsel;