diff --git a/benchmark.py b/benchmark.py
--- a/benchmark.py
+++ b/benchmark.py
@@ -11,6 +11,7 @@
 import shutil
 import subprocess
 import sys
+from tempfile import TemporaryDirectory
 from typing import Set
 
 import click
@@ -118,15 +119,16 @@
         format="%(asctime)s %(message)s",
         datefmt="%m/%d/%Y %I:%M:%S %p",
     )
-
     try:
-        subprocess.run(
-            ["tar", "xvf", repo_path, "-C", temp_path],
-            check=True,
-            stdout=subprocess.DEVNULL,
-            stderr=sys.stderr,
-        )
-        run_experiments(repo_path, temp_path, kb_state, set(algos))
+        repo_id = Path(repo_path).parts[-1].split(".")[0]
+        with TemporaryDirectory(prefix=repo_id + "_", dir=temp_path) as tmp_dir:
+            subprocess.run(
+                ["tar", "xf", repo_path, "-C", tmp_dir, "--strip-components=1"],
+                check=True,
+                stdout=subprocess.DEVNULL,
+                stderr=sys.stderr,
+            )
+            run_experiments(repo_path, temp_path, kb_state, set(algos))
     except Exception as e:
         logging.exception(e)
     except IOError as ioerror:
diff --git a/run_benchmark.sh b/run_benchmark.sh
--- a/run_benchmark.sh
+++ b/run_benchmark.sh
@@ -28,6 +28,9 @@
     algos="$algos -a $i"
 done
 
+# print headers
+echo "repo_id,origin,commit_id,kb_state,repo_size,algorithm_name,kb_queries,swhids_queried"
+
 while IFS= read -r repo;
 do
     ./benchmark.py $repo $temp_dir $kb_state $algos
diff --git a/swh/scanner/benchmark_algos.py b/swh/scanner/benchmark_algos.py
--- a/swh/scanner/benchmark_algos.py
+++ b/swh/scanner/benchmark_algos.py
@@ -293,7 +293,7 @@
     """
 
     def _scan(root_path, source_tree, sre_patterns):
-        dirpath, dnames, fnames = next(os.walk(root_path))
+        dirpath, dnames, fnames = next(os.walk(root_path, followlinks=False))
         dirpath = Path(dirpath)
 
         if fnames:
@@ -336,7 +336,8 @@
             reg_obj for reg_obj in extract_regex_objs(Path(root), exclude_patterns)
         }
 
-    repo_id = Path(root).parts[-1]
+    # temporary directory prefix
+    repo_id = Path(root).parts[-1].split("_")[0]
     counter: collections.Counter = collections.Counter()
     counter["api_calls"] = 0
     counter["queries"] = 0
@@ -356,9 +357,10 @@
             backend_name,
             len(source_tree),
             algo,
+            -1,
             min_queries,
         )
-        print(min_result)
+        print(*min_result, sep=",")
         return
     elif algo == "stopngo":
         stopngo(source_tree, api_url, counter)
@@ -380,4 +382,4 @@
         counter["queries"],
     )
 
-    print(result)
+    print(*result, sep=",")