Perfprofd: Add support for sampling frequency

Allow sampling frequency (-f) besides sampling period (-c), and
support simpleperf default values (when neither is set).

(cherry picked from commit e4b2ed98a9a4a35ac4bb46c20b1599e0889eb3a3)

Bug: 73175642
Test: mmma system/extras/perfprofd
Test: perfprofd_test
Merged-In: I40d7472bc45f5efd33687f9d8a5d6493343091c3
Change-Id: I40d7472bc45f5efd33687f9d8a5d6493343091c3

4 files changed, 25 insertions, 8 deletions

diff --git a/perfprofd/binder_interface/perfprofd_config.proto b/perfprofd/binder_interface/perfprofd_config.proto
index c25aa93b..37c369c2 100644
--- a/perfprofd/binder_interface/perfprofd_config.proto
+++ b/perfprofd/binder_interface/perfprofd_config.proto
@@ -33,8 +33,12 @@ message ProfilingConfig {
 
   // Desired sampling period (passed to perf -c option). Small
   // sampling periods can perturb the collected profiles, so enforce
-  // min/max.
+  // min/max. A value of 0 means perf default. sampling_frequency
+  // takes priority.
   optional uint32 sampling_period = 7;
+  // Desired sampling frequency (passed to perf -f option). A value of 0
+  // means using sampling_period or default.
+  optional uint32 sampling_frequency = 22;
   // Length of time to collect samples (number of seconds for 'perf
   // record -a' run).
   optional uint32 sample_duration_in_s = 8;
diff --git a/perfprofd/config.h b/perfprofd/config.h
index 774f7e86..0ee23099 100644
--- a/perfprofd/config.h
+++ b/perfprofd/config.h
@@ -52,8 +52,12 @@ struct Config {
 
   // Desired sampling period (passed to perf -c option). Small
   // sampling periods can perturb the collected profiles, so enforce
-  // min/max.
-  uint32_t sampling_period = 5000;
+  // min/max. A value of 0 means perf default. sampling_frequency
+  // takes priority.
+  uint32_t sampling_period = 0;
+  // Desired sampling frequency (passed to perf -f option). A value of 0
+  // means using sampling_period or default.
+  uint32_t sampling_frequency = 0;
   // Length of time to collect samples (number of seconds for 'perf
   // record -a' run).
   uint32_t sample_duration_in_s = 2;
diff --git a/perfprofd/configreader.cc b/perfprofd/configreader.cc
index ac78f276..5d52b26e 100644
--- a/perfprofd/configreader.cc
+++ b/perfprofd/configreader.cc
@@ -91,7 +91,9 @@ void ConfigReader::addDefaultEntries()
   addStringEntry("perf_path", config.perf_path.c_str());
 
   // Desired sampling period (passed to perf -c option).
-  addUnsignedEntry("sampling_period", config.sampling_period, 1, UINT32_MAX);
+  addUnsignedEntry("sampling_period", config.sampling_period, 0, UINT32_MAX);
+  // Desired sampling frequency (passed to perf -f option).
+  addUnsignedEntry("sampling_frequency", config.sampling_frequency, 0, UINT32_MAX);
 
   // Length of time to collect samples (number of seconds for 'perf
   // record -a' run).
diff --git a/perfprofd/perfprofdcore.cc b/perfprofd/perfprofdcore.cc
index 69508ad6..d7b0e9b4 100644
--- a/perfprofd/perfprofdcore.cc
+++ b/perfprofd/perfprofdcore.cc
@@ -491,10 +491,17 @@ static PROFILE_RESULT invoke_perf(Config& config,
     argv[slot++] = "-o";
     argv[slot++] = data_file_path.c_str();
 
-    // -c N
-    argv[slot++] = "-c";
-    std::string p_str = android::base::StringPrintf("%u", sampling_period);
-    argv[slot++] = p_str.c_str();
+    // -c/f N
+    std::string p_str;
+    if (config.sampling_frequency > 0) {
+      argv[slot++] = "-f";
+      p_str = android::base::StringPrintf("%u", sampling_period);
+      argv[slot++] = p_str.c_str();
+    } else if (config.sampling_period > 0) {
+      argv[slot++] = "-c";
+      p_str = android::base::StringPrintf("%u", sampling_period);
+      argv[slot++] = p_str.c_str();
+    }
 
     // -g if desired
     if (stack_profile_opt)