Return-path: Received: from yw-out-2324.google.com ([74.125.46.31]:28657 "EHLO yw-out-2324.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752856AbZESRsb convert rfc822-to-8bit (ORCPT ); Tue, 19 May 2009 13:48:31 -0400 Received: by yw-out-2324.google.com with SMTP id 5so2481852ywb.1 for ; Tue, 19 May 2009 10:48:32 -0700 (PDT) MIME-Version: 1.0 Date: Wed, 20 May 2009 01:48:32 +0800 Message-ID: <60ce8d250905191048t46e3848fw3416ecd793dab9d1@mail.gmail.com> Subject: Throughput is not changed when setting to a much higher bit rate From: Dongas To: linux-wireless@vger.kernel.org Content-Type: text/plain; charset=windows-1252 Sender: linux-wireless-owner@vger.kernel.org List-ID: Hi ALL, I'm doing the performance profiling of our WiFi module with iperf. The module is based on Marvell 8686 chipset with Libertas driver. A strange issue i encounterred is that even i changed to a higher bit rate ,the result of iperf seems that the bandwidth/troughput is still not changed. Details are as follows: 1. First test with default Bit Rate -1Mb/s # iwconfig eth1 IEEE 802.11b/g ESSID:"dlink" Mode:Managed Frequency:2.437 GHz Access Point: 00:24:01:25:18:8A Bit Rate:1 Mb/s Tx-Power=13 dBm Retry limit:8 RTS thr=2347 B Fragment thr=2346 B Encryption key:off Power Management:off Link Quality=100/100 Signal level=-22 dBm Noise level=-93 dBm Rx invalid nwid:0 Rx invalid crypt:0 Rx invalid frag:125310 Tx excessive retries:1120 Invalid misc:2988 Missed beacon:0 # # iperf -c 172.31.42.51 -i 5 -t 60 ------------------------------------------------------------ Client connecting to 172.31.42.51, TCP port 5001 TCP window size: 16.0 KByte (default) ------------------------------------------------------------ [ 3] local 172.31.42.218 port 33228 connected with 172.31.42.51 port 5001 [ ID] Interval Transfer Bandwidth [ 3] 0.0- 5.0 sec 792 KBytes 1.30 Mbits/sec [ ID] Interval Transfer Bandwidth [ 3] 5.0-10.0 sec 680 KBytes 1.11 Mbits/sec ?? The bandwidth tested out with iperf is around 1.1Mb/s. 2. Change to a higner Bit Rate (11Mb/s) and re-test # iwconfig eth1 rate 11M fixed # iwconfig eth1 IEEE 802.11b/g ESSID:"dlink" Mode:Managed Frequency:2.437 GHz Access Point: 00:24:01:25:18:8A Bit Rate=11 Mb/s Tx-Power=13 dBm Retry limit:8 RTS thr=2347 B Fragment thr=2346 B Encryption key:off Power Management:off Link Quality=100/100 Signal level=-22 dBm Noise level=-94 dBm Rx invalid nwid:0 Rx invalid crypt:0 Rx invalid frag:125610 Tx excessive retries:1120 Invalid misc:2988 Missed beacon:0 # iperf -c 172.31.42.51 -i 5 -t 60 ------------------------------------------------------------ Client connecting to 172.31.42.51, TCP port 5001 TCP window size: 16.0 KByte (default) ------------------------------------------------------------ [ 3] local 172.31.42.218 port 33229 connected with 172.31.42.51 port 5001 [ ID] Interval Transfer Bandwidth [ 3] 0.0- 5.0 sec 776 KBytes 1.27 Mbits/sec [ ID] Interval Transfer Bandwidth [ 3] 5.0-10.0 sec 720 KBytes 1.18 Mbits/sec [ ID] Interval Transfer Bandwidth [ 3] 10.0-15.0 sec 680 KBytes 1.11 Mbits/sec The bandwidth tested out with iperf is still around 1.1Mb/s. Why the bandwidth is not changed when bit rate is changed to 11Mb/s? Any thing wrong? Thanks Regards Dongas