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Re: bluetooth 2.0 is extremely slow



-------- Original Message  --------
Subject: Re: bluetooth 2.0 is extremely slow
From: Mike Cronenworth <mike cchtml com>
To: mike cchtml com, Development discussions related to Fedora <fedora-devel-list redhat com>
Cc: Bastien Nocera <bnocera redhat com>
Date: 04/09/2008 09:53 PM

OK,

I applied the attached patch. I'm putting this up for review, and any suggestions (should this be posted somewhere else, etc.). My transfer time went from 40 seconds to 10 seconds. It now matches Windows XP performance. Just add it to the RPM spec like the existing patches.

Regards,
Michael


After further testing I've created a proper patch. These are my results based on the attached patch. Each MTU was tested twice using "open_push" as the receiver program and using the "gnome-obex-server" program.

Bluetooth 2.0 - 1070k file transfer from phone to computer
1024 MTU - 40 seconds (default MTU)
8192 MTU - 20 seconds
16384 MTU - 10 seconds
32768 MTU - 11 seconds
65535 MTU - 12 seconds

Bluetooth 1.1 - 1070k file transfer from phone to computer
1024 MTU - 52 seconds (default MTU)
8192 MTU - 30 seconds
16384 MTU - 34 seconds

I revised the patch to not change the minimum MTU. It had no effect on speeds. 16k seems to be the sweet spot. This makes *huge* differences for both 1.1 and 2.0. It seems no one with OpenOBEX bothered to test transfer speeds... kind of unsettling. I will make a Bugzilla report and join the bluez list later today.

Regards,
Mike
--- openobex-1.3/include/obex_const.h.mtu	2006-03-08 06:18:55.000000000 -0600
+++ openobex-1.3/include/obex_const.h	2008-04-09 21:26:53.000000000 -0500
@@ -192,8 +192,8 @@
 #define OBEX_RSP_DATABASE_LOCKED	0x61
 
 /* Min, Max and default transport MTU */
-#define OBEX_DEFAULT_MTU	1024
+#define OBEX_DEFAULT_MTU	16384
 #define OBEX_MINIMUM_MTU	255
 #define OBEX_MAXIMUM_MTU	65535
 
 /* Optimum MTU for various transport (optimum for throughput).


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