Merge pull request iovisor#3765 from bveldhoen/usdt_sample_update

Updated usdt_sample for ubuntu 21.10 (and python3)

examples/usdt_sample/.gitignore

@@ -0,0 +1 @@
+**/build*/

examples/usdt_sample/CMakeLists.txt

@@ -1,4 +1,4 @@
-cmake_minimum_required(VERSION 3.0)
+cmake_minimum_required(VERSION 3.12)
 
 # This sample requires C++11 enabled.
 set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -std=c++11 -Wall -Weffc++")

examples/usdt_sample/scripts/bpf_text_shared.c

@@ -4,15 +4,27 @@
 /**
  * @brief Helper method to filter based on the specified inputString.
  * @param inputString The operation input string to check against the filter.
- * @return True if the specified inputString starts with the hard-coded FILTER_STRING; otherwise, false.
+ * @return True if the specified inputString starts with the hard-coded filter string; otherwise, false.
  */
 static inline bool filter(char const* inputString)
 {
- char needle[] = "FILTER_STRING"; ///< The FILTER STRING is replaced by python code.
- char haystack[sizeof(needle)] = {};
- bpf_probe_read_user(&haystack, sizeof(haystack), (void*)inputString);
- for (int i = 0; i < sizeof(needle) - 1; ++i) {
- if (needle[i] != haystack[i]) {
+ static const char* null_ptr = 0x0;
+ static const char null_terminator = '\0';
+
+ static const char filter_string[] = "FILTER_STRING"; ///< The filter string is replaced by python code.
+ if (null_ptr == inputString) {
+ return false;
+ }
+
+ // Compare until (not including) the null-terminator for filter_string
+ for (int i = 0; i < sizeof(filter_string) - 1; ++i) {
+ char c1 = *inputString++;
+ if (null_terminator == c1) {
+ return false; // If the null-terminator for inputString was reached, it can not be equal to filter_string.
+ }
+
+ char c2 = filter_string[i];
+ if (c1 != c2) {
  return false;
  }
  }
@@ -45,7 +57,7 @@ int trace_operation_start(struct pt_regs* ctx)
  struct start_data_t start_data = {};
  bpf_usdt_readarg_p(2, ctx, &start_data.input, sizeof(start_data.input));
 
- FILTER ///< Replaced by python code.
+ FILTER_STATEMENT ///< Replaced by python code.
 
  bpf_usdt_readarg(1, ctx, &start_data.operation_id);
 

examples/usdt_sample/scripts/lat_avg.py

@@ -12,23 +12,25 @@
  formatter_class=argparse.RawDescriptionHelpFormatter)
 parser.add_argument("-p", "--pid", type=int, help="The id of the process to trace.")
 parser.add_argument("-i", "--interval", type=int, help="The interval in seconds on which to report the latency distribution.")
-parser.add_argument("-c", "--count", type=int, default=16, help="The count of samples over which to calculate the moving average.")
+parser.add_argument("-c", "--count", type=int, default=16, help="The maximum number of samples over which to calculate the moving average.")
 parser.add_argument("-f", "--filterstr", type=str, default="", help="The prefix filter for the operation input. If specified, only operations for which the input string starts with the filterstr are traced.")
-parser.add_argument("-v", "--verbose", dest="verbose", action="store_true", help="If true, will output verbose logging information.")
+parser.add_argument("-v", "--verbose", dest="verbose", action="store_true", help="If true, will output generated bpf program and verbose logging information.")
+parser.add_argument("-s", "--sdt", dest="sdt", action="store_true", help="If true, will use the probes, created by systemtap's dtrace.")
+
 parser.set_defaults(verbose=False)
 args = parser.parse_args()
 this_pid = int(args.pid)
 this_interval = int(args.interval)
-this_count = int(args.count)
+this_maxsamplesize = int(args.count)
 this_filter = str(args.filterstr)
 
 if this_interval < 1:
  print("Invalid value for interval, using 1.")
  this_interval = 1
 
-if this_count < 1:
- print("Invalid value for count, using 1.")
- this_count = 1
+if this_maxsamplesize < 1:
+ print("Invalid value for this_maxsamplesize, using 1.")
+ this_maxsamplesize = 1
 
 debugLevel=0
 if args.verbose:
@@ -39,18 +41,18 @@
 bpf_text = open(bpf_text_shared, 'r').read()
 bpf_text += """
 
-const u32 MAX_SAMPLES = SAMPLE_COUNT;
+const u32 max_sample_size = MAX_SAMPLE_SIZE;
 
 struct hash_key_t
 {
- char input[64];
+ char input[64]; // The operation id is used as key
 };
 
 struct hash_leaf_t
 {
- u32 count;
- u64 total;
- u64 average;
+ u32 sample_size; // Number of operation samples taken
+ u64 total; // Cumulative duration of the operations
+ u64 average; // Moving average duration of the operations
 };
 
 /**
@@ -83,45 +85,49 @@
  return 0;
  }
 
- if (hash_leaf->count < MAX_SAMPLES) {
- hash_leaf->count++;
+ if (hash_leaf->sample_size < max_sample_size) {
+ ++hash_leaf->sample_size;
  } else {
  hash_leaf->total -= hash_leaf->average;
  }
 
  hash_leaf->total += duration;
- hash_leaf->average = hash_leaf->total / hash_leaf->count;
+ hash_leaf->average = hash_leaf->total / hash_leaf->sample_size;
 
  return 0;
 }
 """
 
-bpf_text = bpf_text.replace("SAMPLE_COUNT", str(this_count))
+bpf_text = bpf_text.replace("MAX_SAMPLE_SIZE", str(this_maxsamplesize))
 bpf_text = bpf_text.replace("FILTER_STRING", this_filter)
 if this_filter:
- bpf_text = bpf_text.replace("FILTER", "if (!filter(start_data.input)) { return 0; }")
+ bpf_text = bpf_text.replace("FILTER_STATEMENT", "if (!filter(start_data.input)) { return 0; }")
 else:
- bpf_text = bpf_text.replace("FILTER", "")
+ bpf_text = bpf_text.replace("FILTER_STATEMENT", "")
 
 # Create USDT context
-print("Attaching probes to pid %d" % this_pid)
+print("lat_avg.py - Attaching probes to pid: %d; filter: %s" % (this_pid, this_filter))
 usdt_ctx = USDT(pid=this_pid)
-usdt_ctx.enable_probe(probe="operation_start", fn_name="trace_operation_start")
-usdt_ctx.enable_probe(probe="operation_end", fn_name="trace_operation_end")
+
+if args.sdt:
+ usdt_ctx.enable_probe(probe="usdt_sample_lib1_sdt:operation_start_sdt", fn_name="trace_operation_start")
+ usdt_ctx.enable_probe(probe="usdt_sample_lib1_sdt:operation_end_sdt", fn_name="trace_operation_end")
+else:
+ usdt_ctx.enable_probe(probe="usdt_sample_lib1:operation_start", fn_name="trace_operation_start")
+ usdt_ctx.enable_probe(probe="usdt_sample_lib1:operation_end", fn_name="trace_operation_end")
 
 # Create BPF context, load BPF program
 bpf_ctx = BPF(text=bpf_text, usdt_contexts=[usdt_ctx], debug=debugLevel)
 
 print("Tracing... Hit Ctrl-C to end.")
 
 lat_hash = bpf_ctx.get_table("lat_hash")
+print("%-12s %-64s %8s %16s" % ("time", "input", "sample_size", "latency (us)"))
 while (1):
  try:
  sleep(this_interval)
  except KeyboardInterrupt:
  exit()
 
- print("[%s]" % strftime("%H:%M:%S"))
- print("%-64s %8s %16s" % ("input", "count", "latency (us)"))
  for k, v in lat_hash.items():
- print("%-64s %8d %16d" % (k.input, v.count, v.average / 1000))
+ print("%-12s %-64s %8d %16d" % (strftime("%H:%M:%S"), k.input, v.sample_size, v.average / 1000))

examples/usdt_sample/scripts/lat_dist.py

@@ -13,7 +13,9 @@
 parser.add_argument("-p", "--pid", type=int, help="The id of the process to trace.")
 parser.add_argument("-i", "--interval", type=int, help="The interval in seconds on which to report the latency distribution.")
 parser.add_argument("-f", "--filterstr", type=str, default="", help="The prefix filter for the operation input. If specified, only operations for which the input string starts with the filterstr are traced.")
-parser.add_argument("-v", "--verbose", dest="verbose", action="store_true", help="If true, will output verbose logging information.")
+parser.add_argument("-v", "--verbose", dest="verbose", action="store_true", help="If true, will output generated bpf program and verbose logging information.")
+parser.add_argument("-s", "--sdt", dest="sdt", action="store_true", help="If true, will use the probes, created by systemtap's dtrace.")
+
 parser.set_defaults(verbose=False)
 args = parser.parse_args()
 this_pid = int(args.pid)
@@ -67,26 +69,33 @@
  dist_key.slot = bpf_log2l(duration / 1000);
  start_hash.delete(&operation_id);
 
- dist.increment(dist_key);
+ dist.atomic_increment(dist_key);
  return 0;
 }
 """
 
 bpf_text = bpf_text.replace("FILTER_STRING", this_filter)
 if this_filter:
- bpf_text = bpf_text.replace("FILTER", "if (!filter(start_data.input)) { return 0; }")
+ bpf_text = bpf_text.replace("FILTER_STATEMENT", "if (!filter(start_data.input)) { return 0; }")
 else:
- bpf_text = bpf_text.replace("FILTER", "")
+ bpf_text = bpf_text.replace("FILTER_STATEMENT", "")
 
 # Create USDT context
-print("Attaching probes to pid %d" % this_pid)
+print("lat_dist.py - Attaching probes to pid: %d; filter: %s" % (this_pid, this_filter))
 usdt_ctx = USDT(pid=this_pid)
-usdt_ctx.enable_probe(probe="operation_start", fn_name="trace_operation_start")
-usdt_ctx.enable_probe(probe="operation_end", fn_name="trace_operation_end")
+
+if args.sdt:
+ usdt_ctx.enable_probe(probe="usdt_sample_lib1_sdt:operation_start_sdt", fn_name="trace_operation_start")
+ usdt_ctx.enable_probe(probe="usdt_sample_lib1_sdt:operation_end_sdt", fn_name="trace_operation_end")
+else:
+ usdt_ctx.enable_probe(probe="usdt_sample_lib1:operation_start", fn_name="trace_operation_start")
+ usdt_ctx.enable_probe(probe="usdt_sample_lib1:operation_end", fn_name="trace_operation_end")
 
 # Create BPF context, load BPF program
 bpf_ctx = BPF(text=bpf_text, usdt_contexts=[usdt_ctx], debug=debugLevel)
 
+print("Tracing... Hit Ctrl-C to end.")
+
 start = 0
 dist = bpf_ctx.get_table("dist")
 while (1):

examples/usdt_sample/scripts/latency.py

@@ -12,7 +12,9 @@
  formatter_class=argparse.RawDescriptionHelpFormatter)
 parser.add_argument("-p", "--pid", type=int, help="The id of the process to trace.")
 parser.add_argument("-f", "--filterstr", type=str, default="", help="The prefix filter for the operation input. If specified, only operations for which the input string starts with the filterstr are traced.")
-parser.add_argument("-v", "--verbose", dest="verbose", action="store_true", help="If true, will output verbose logging information.")
+parser.add_argument("-v", "--verbose", dest="verbose", action="store_true", help="If true, will output generated bpf program and verbose logging information.")
+parser.add_argument("-s", "--sdt", dest="sdt", action="store_true", help="If true, will use the probes, created by systemtap's dtrace.")
+
 parser.set_defaults(verbose=False)
 args = parser.parse_args()
 this_pid = int(args.pid)
@@ -76,15 +78,20 @@
 
 bpf_text = bpf_text.replace("FILTER_STRING", this_filter)
 if this_filter:
- bpf_text = bpf_text.replace("FILTER", "if (!filter(start_data.input)) { return 0; }")
+ bpf_text = bpf_text.replace("FILTER_STATEMENT", "if (!filter(start_data.input)) { return 0; }")
 else:
- bpf_text = bpf_text.replace("FILTER", "")
+ bpf_text = bpf_text.replace("FILTER_STATEMENT", "")
 
 # Create USDT context
-print("Attaching probes to pid %d" % this_pid)
+print("latency.py - Attaching probes to pid: %d; filter: %s" % (this_pid, this_filter))
 usdt_ctx = USDT(pid=this_pid)
-usdt_ctx.enable_probe(probe="operation_start", fn_name="trace_operation_start")
-usdt_ctx.enable_probe(probe="operation_end", fn_name="trace_operation_end")
+
+if args.sdt:
+ usdt_ctx.enable_probe(probe="usdt_sample_lib1_sdt:operation_start_sdt", fn_name="trace_operation_start")
+ usdt_ctx.enable_probe(probe="usdt_sample_lib1_sdt:operation_end_sdt", fn_name="trace_operation_end")
+else:
+ usdt_ctx.enable_probe(probe="usdt_sample_lib1:operation_start", fn_name="trace_operation_start")
+ usdt_ctx.enable_probe(probe="usdt_sample_lib1:operation_end", fn_name="trace_operation_end")
 
 # Create BPF context, load BPF program
 bpf_ctx = BPF(text=bpf_text, usdt_contexts=[usdt_ctx], debug=debugLevel)