perf lock contention: Allow 'mmap_lock' in -L/--lock-filter

The -L/--lock-filter option is to specify target locks by name or
address.  It's basically for global locks where name or address is known
and fixed.  But 'mmap_lock' is a per-process lock so it cannot be used
for the -L option.

  $ sudo perf lock con -ab -L mmap_lock
  ignore unknown symbol: mmap_lock
  libbpf: map 'addr_filter': failed to create: -EINVAL
  libbpf: failed to load BPF skeleton 'lock_contention_bpf': -EINVAL
  Failed to load lock-contention BPF skeleton
  lock contention BPF setup failed

However, it's still a common source of contention especially in a large
process so we want to use it for the -L/--lock-filter option.  As there
is check_lock_type() to check mmap_lock at runtime, let's used it to
filter mmap_locks as a special case.

Of course, this only works with -b/--use-bpf option.

  $ sudo perf lock con -b -L mmap_lock -- perf bench mem mmap -f demand -t 2
  # Running 'mem/mmap' benchmark:
  # function 'demand' (Demand loaded mmap())
  # Copying 1MB bytes ...

         2.679184 GB/sec/thread	( +-   1.78% )
   contended   total wait     max wait     avg wait         type   caller

           1     15.22 us     15.22 us     15.22 us      rwsem:W   __vm_munmap+0x7e
           1      7.72 us      7.72 us      7.72 us      rwsem:R   lock_mm_and_find_vma+0x97

Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: James Clark <james.clark@linaro.org>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Suchit Karunakaran <suchitkarunakaran@gmail.com>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

diff --git a/tools/perf/tests/shell/lock_contention.sh b/tools/perf/tests/shell/lock_contention.sh
index 6dd90519f45cec1d7e6096e022a48052ed5ff39c..52e8b9db9fbd884410b964a0f7b4a232295fbc9a 100755 (executable)
--- a/tools/perf/tests/shell/lock_contention.sh
+++ b/tools/perf/tests/shell/lock_contention.sh
@@ -208,6 +208,17 @@ test_lock_filter()
                err=1
                exit
        fi
+
+       perf lock con -b -L mmap_lock -q -- perf bench mem mmap -t 2 -l 10 > /dev/null 2> ${result}
+
+       # find out the type of mmap_lock
+       test_lock_filter_type=$(head -1 "${result}" | awk '{ print $8 }' | sed -e 's/:.*//')
+
+       if [ "$(grep -c -v "${test_lock_filter_type}" "${result}")" != "0" ]; then
+               echo "[Fail] BPF result should not have non-${test_lock_filter_type} locks:" "$(cat "${result}")"
+               err=1
+               exit
+       fi
 }
 
 test_stack_filter()

diff --git a/tools/perf/util/bpf_lock_contention.c b/tools/perf/util/bpf_lock_contention.c
index cbd7435579feaf8e837c587795db650ed7e0eb6a..eb8e29b8064b7348ce33f079f884d1d7cc1178f0 100644 (file)
--- a/tools/perf/util/bpf_lock_contention.c
+++ b/tools/perf/util/bpf_lock_contention.c
@@ -186,6 +186,7 @@ int lock_contention_prepare(struct lock_contention *con)
        int ncpus = 1, ntasks = 1, ntypes = 1, naddrs = 1, ncgrps = 1, nslabs = 1;
        struct evlist *evlist = con->evlist;
        struct target *target = con->target;
+       bool has_mmap_lock = false;
 
        /* make sure it loads the kernel map before lookup */
        map__load(machine__kernel_map(con->machine));
@@ -244,6 +245,11 @@ int lock_contention_prepare(struct lock_contention *con)
                unsigned long *addrs;
 
                for (i = 0; i < con->filters->nr_syms; i++) {
+                       if (!strcmp(con->filters->syms[i], "mmap_lock")) {
+                               has_mmap_lock = true;
+                               continue;
+                       }
+
                        sym = machine__find_kernel_symbol_by_name(con->machine,
                                                                  con->filters->syms[i],
                                                                  &kmap);
@@ -263,7 +269,7 @@ int lock_contention_prepare(struct lock_contention *con)
                        addrs[con->filters->nr_addrs++] = map__unmap_ip(kmap, sym->start);
                        con->filters->addrs = addrs;
                }
-               naddrs = con->filters->nr_addrs;
+               naddrs = con->filters->nr_addrs ?: has_mmap_lock;
                skel->rodata->has_addr = 1;
        }
 
@@ -298,6 +304,7 @@ int lock_contention_prepare(struct lock_contention *con)
        skel->rodata->aggr_mode = con->aggr_mode;
        skel->rodata->needs_callstack = con->save_callstack;
        skel->rodata->lock_owner = con->owner;
+       skel->rodata->has_mmap_lock = has_mmap_lock;
 
        if (con->aggr_mode == LOCK_AGGR_CGROUP || con->filters->nr_cgrps) {
                if (cgroup_is_v2("perf_event"))

diff --git a/tools/perf/util/bpf_skel/lock_contention.bpf.c b/tools/perf/util/bpf_skel/lock_contention.bpf.c
index 5c8431be674acd94f8bf6e0d3688f055b17ed1b8..d4186ae9f85c7f0b33aed0309d1f2dfc8899ba55 100644 (file)
--- a/tools/perf/util/bpf_skel/lock_contention.bpf.c
+++ b/tools/perf/util/bpf_skel/lock_contention.bpf.c
@@ -191,6 +191,7 @@ const volatile int has_type;
 const volatile int has_addr;
 const volatile int has_cgroup;
 const volatile int has_slab;
+const volatile int has_mmap_lock;
 const volatile int needs_callstack;
 const volatile int stack_skip;
 const volatile int lock_owner;
@@ -221,6 +222,8 @@ int data_map_full;
 struct task_struct *bpf_task_from_pid(s32 pid) __ksym __weak;
 void bpf_task_release(struct task_struct *p) __ksym __weak;
 
+static inline __u32 check_lock_type(__u64 lock, __u32 flags);
+
 static inline __u64 get_current_cgroup_id(void)
 {
        struct task_struct *task;
@@ -246,6 +249,8 @@ static inline __u64 get_current_cgroup_id(void)
 
 static inline int can_record(u64 *ctx)
 {
+       bool is_addr_ok = false;
+
        if (has_cpu) {
                __u32 cpu = bpf_get_smp_processor_id();
                __u8 *ok;
@@ -278,8 +283,10 @@ static inline int can_record(u64 *ctx)
                __u64 addr = ctx[0];
 
                ok = bpf_map_lookup_elem(&addr_filter, &addr);
-               if (!ok && !has_slab)
+               if (!ok && !has_slab && !has_mmap_lock)
                        return 0;
+
+               is_addr_ok = !!ok;
        }
 
        if (has_cgroup) {
@@ -291,6 +298,10 @@ static inline int can_record(u64 *ctx)
                        return 0;
        }
 
+       if (is_addr_ok)
+               return 1;
+
+       /* slab and mmap_lock are part of the addr_filter */
        if (has_slab && bpf_get_kmem_cache) {
                __u8 *ok;
                __u64 addr = ctx[0];
@@ -298,7 +309,17 @@ static inline int can_record(u64 *ctx)
 
                kmem_cache_addr = (long)bpf_get_kmem_cache(addr);
                ok = bpf_map_lookup_elem(&slab_filter, &kmem_cache_addr);
-               if (!ok)
+               if (ok)
+                       return 1;
+               else if (!has_mmap_lock)
+                       return 0;
+       }
+
+       if (has_mmap_lock) {
+               __u64 lock = ctx[0];
+               __u32 flag = ctx[1];
+
+               if (check_lock_type(lock, flag) != LCD_F_MMAP_LOCK)
                        return 0;
        }