http-lib: make perf shorter

Taking measurements in practice doesn't lead to improved accuracy. Also change
the tests so more than one sample is collected and can know how noisy the
measurements really are.

Here's an example of a run, including the result before the change:

```
   $ ./test_client.exe --perf
-  1 thread non-persistent connections:        4896.0 +/- 0.0 RPCs/sec
-  1 thread non-persistent connections (query):        4811.0 +/- 0.0 RPCs/sec
-  10 threads non-persistent connections: 7175.0 +/- 0.0 RPCs/sec
-  1 thread persistent connection:             16047.0 +/- 0.0 RPCs/sec
-  10 threads persistent connections: 7713.0 +/- 0.0 RPCs/sec
+  1 thread non-persistent connections:         5042.0 +/- 247.5 RPCs/sec
+  1 thread non-persistent connections (query): 5173.0 +/- 216.0 RPCs/sec
+  10 threads non-persistent connections:       7678.0 +/- 2241.2 RPCs/sec
+  1 thread persistent connection:              21814.0 +/- 2124.6 RPCs/sec
+  10 threads persistent connections:           10154.0 +/- 2461.9 RPCs/sec
```

Signed-off-by: Pau Ruiz Safont <[email protected]>

ocaml/libs/http-lib/test_client.ml

@@ -117,44 +117,44 @@ let perf () =
   let use_fastpath = !use_fastpath in
   let use_framing = !use_framing in
   let transport = if !use_ssl then with_stunnel else with_connection in
-  Printf.printf "1 thread non-persistent connections:        " ;
+  Printf.printf "1 thread non-persistent connections:         " ;
   let nonpersistent =
-    let@ () = sample 1 in
-    let@ () = per_nsec 1. in
+    let@ () = sample 10 in
+    let@ () = per_nsec 0.1 in
     transport !ip !port (one ~use_fastpath ~use_framing false)
   in
   Printf.printf "%s RPCs/sec\n%!" (Normal_population.to_string nonpersistent) ;
-  Printf.printf "1 thread non-persistent connections (query):        " ;
+  Printf.printf "1 thread non-persistent connections (query): " ;
   let nonpersistent_query =
-    let@ () = sample 1 in
-    let@ () = per_nsec 1. in
+    let@ () = sample 10 in
+    let@ () = per_nsec 0.1 in
     transport !ip !port (query ~use_fastpath ~use_framing false)
   in
   Printf.printf "%s RPCs/sec\n%!"
     (Normal_population.to_string nonpersistent_query) ;
-  Printf.printf "10 threads non-persistent connections: " ;
+  Printf.printf "10 threads non-persistent connections:       " ;
   let thread_nonpersistent =
-    let@ () = sample 1 in
+    let@ () = sample 10 in
     let@ () = threads 10 in
-    let@ () = per_nsec 5. in
+    let@ () = per_nsec 0.1 in
     transport !ip !port (one ~use_fastpath ~use_framing false)
   in
   Printf.printf "%s RPCs/sec\n%!"
     (Normal_population.to_string thread_nonpersistent) ;
-  Printf.printf "1 thread persistent connection:             " ;
+  Printf.printf "1 thread persistent connection:              " ;
   let persistent =
-    let@ () = sample 1 in
+    let@ () = sample 10 in
     let@ s = transport !ip !port in
-    let@ () = per_nsec 1. in
+    let@ () = per_nsec 0.1 in
     one ~use_fastpath ~use_framing true s
   in
   Printf.printf "%s RPCs/sec\n%!" (Normal_population.to_string persistent) ;
-  Printf.printf "10 threads persistent connections: " ;
+  Printf.printf "10 threads persistent connections:           " ;
   let thread_persistent =
-    let@ () = sample 1 in
+    let@ () = sample 10 in
     let@ () = threads 10 in
     let@ s = transport !ip !port in
-    let@ () = per_nsec 5. in
+    let@ () = per_nsec 0.1 in
     one ~use_fastpath ~use_framing true s
   in
   Printf.printf "%s RPCs/sec\n%!" (Normal_population.to_string thread_persistent)