batctl: Correct mdev calculation in ping subcommand

Message ID	4BF55C08.7010704@tiwoc.de (mailing list archive)
State	Superseded, archived
Headers	Message-ID: <4BF55C08.7010704@tiwoc.de> Date: Thu, 20 May 2010 17:58:00 +0200 From: Daniel Seither <post@tiwoc.de> User-Agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.1.9) Gecko/20100423 Lightning/1.0b1 Thunderbird/3.0.4 MIME-Version: 1.0 To: The list for a Better Approach To Mobile Ad-hoc Networking <b.a.t.m.a.n@lists.open-mesh.org> Content-Type: text/plain; charset=ISO-8859-15 Content-Transfer-Encoding: 7bit Subject: [B.A.T.M.A.N.] [PATCH] batctl: Correct mdev calculation in ping subcommand Precedence: list Reply-To: The list for a Better Approach To Mobile Ad-hoc Networking <b.a.t.m.a.n@lists.open-mesh.org>

Message ID

4BF55C08.7010704@tiwoc.de (mailing list archive)

State

Superseded, archived

Headers

Message-ID: <4BF55C08.7010704@tiwoc.de>
Date: Thu, 20 May 2010 17:58:00 +0200
From: Daniel Seither <post@tiwoc.de>
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To: The list for a Better Approach To Mobile Ad-hoc Networking
	<b.a.t.m.a.n@lists.open-mesh.org>
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Subject: [B.A.T.M.A.N.] [PATCH] batctl: Correct mdev calculation in ping
	subcommand
Precedence: list
Reply-To: The list for a Better Approach To Mobile Ad-hoc Networking
	<b.a.t.m.a.n@lists.open-mesh.org>

Commit Message

Daniel Seither May 20, 2010, 3:58 p.m. UTC

  Fixes the calculation of the mean absolute deviation (mdev)
of the roundtrip times. mdev was previously calculated by
computing the difference of maximum and minimum round trip times.

The calculation is now done using the same formula as in the iputils
ping program.

Signed-off-by: Daniel Seither <post@tiwoc.de>
---

Comments

Daniel Seither May 20, 2010, 4:10 p.m. UTC | #1

Sorry, I sent the wrong version of the patch. I'll send a fixed patch in
a minute...

- Daniel

Am 20.05.2010 17:58, schrieb Daniel Seither:
> Fixes the calculation of the mean absolute deviation (mdev)
> of the roundtrip times. mdev was previously calculated by
> computing the difference of maximum and minimum round trip times.
> 
> The calculation is now done using the same formula as in the iputils
> ping program.
> 
> Signed-off-by: Daniel Seither <post@tiwoc.de>
> ---

diff mbox

Patch

Index: ping.c
===================================================================
--- ping.c	(revision 1659)
+++ ping.c	(working copy)
@@ -76,7 +76,7 @@ 
 	unsigned int seq_counter = 0, packets_out = 0, packets_in = 0, packets_loss;
 	char *dst_string, *mac_string, *rr_string;
 	double time_delta;
-	float min = 0.0, max = 0.0, avg = 0.0;
+	float min = 0.0, max = 0.0, avg = 0.0, mdev = 0.0;
 	uint8_t last_rr_cur = 0, last_rr[BAT_RR_LEN][ETH_ALEN];
 	size_t packet_len;

@@ -260,6 +260,7 @@ 
 			if (time_delta > max)
 				max = time_delta;
 			avg += time_delta;
+			mdev += time_delta * time_delta;
 			packets_in++;
 			break;
 		case DESTINATION_UNREACHABLE:
@@ -289,11 +290,20 @@ 
 	else
 		packets_loss = ((packets_out - packets_in) * 100) / packets_out;

+	if (packets_in) {
+		avg /= packets_in;
+		mdev /= packets_in;
+		mdev = sqrt(mdev - avg * avg);
+	} else {
+		avg = 0.0;
+		mdev = 0.0;
+	}
+
 	printf("--- %s ping statistics ---\n", dst_string);
 	printf("%u packets transmitted, %u received, %u%% packet loss\n",
 		packets_out, packets_in, packets_loss);
 	printf("rtt min/avg/max/mdev = %.3f/%.3f/%.3f/%.3f ms\n",
-		min, (packets_in ? (avg / packets_in) : 0.000), max, (max - min));
+		min, avg, max, mdev);

 	ret = EXIT_SUCCESS;