Return-path: Received: from nm15-vm0.bullet.mail.bf1.yahoo.com ([98.139.212.254]:36144 "HELO nm15-vm0.bullet.mail.bf1.yahoo.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1756088Ab1DHMVS (ORCPT ); Fri, 8 Apr 2011 08:21:18 -0400 Message-ID: <888400.56093.qm@web161618.mail.bf1.yahoo.com> Date: Fri, 8 Apr 2011 05:21:17 -0700 (PDT) From: Walter Goldens Subject: Re: Questions about rt2800usb To: Ivo Van Doorn Cc: Steev Klimaszewski , Jett Chen , Larry Finger , wireless In-Reply-To: <699128.18071.qm@web161601.mail.bf1.yahoo.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Sender: linux-wireless-owner@vger.kernel.org List-ID: > > Try: > > > > iwconfig wlan0 power off > > > > to disable powersaving. > > > > Ivo > > Hi Ivo, > > Disabling power decreased latency substantially to a normal > level, however it paved the way for myriad duplicate > packets. > > rt2800usb: > > PING gmail.com (209.85.229.19) 56(84) bytes of data. > 64 bytes from ww-in-f19.1e100.net (209.85.229.19): > icmp_req=1 ttl=53 time=52.9 ms > 64 bytes from ww-in-f19.1e100.net (209.85.229.19): > icmp_req=2 ttl=53 time=50.2 ms > 64 bytes from ww-in-f19.1e100.net (209.85.229.19): > icmp_req=3 ttl=53 time=51.6 ms > 64 bytes from ww-in-f19.1e100.net (209.85.229.19): > icmp_req=4 ttl=53 time=52.8 ms > 64 bytes from ww-in-f19.1e100.net (209.85.229.19): > icmp_req=5 ttl=53 time=53.3 ms > 64 bytes from ww-in-f19.1e100.net (209.85.229.19): > icmp_req=6 ttl=53 time=51.4 ms > 64 bytes from ww-in-f19.1e100.net (209.85.229.19): > icmp_req=6 ttl=53 time=52.4 ms (DUP!) > 64 bytes from ww-in-f19.1e100.net (209.85.229.19): > icmp_req=6 ttl=53 time=52.5 ms (DUP!) > 64 bytes from ww-in-f19.1e100.net (209.85.229.19): > icmp_req=7 ttl=53 time=51.8 ms > 64 bytes from ww-in-f19.1e100.net (209.85.229.19): > icmp_req=7 ttl=53 time=54.8 ms (DUP!) > 64 bytes from ww-in-f19.1e100.net (209.85.229.19): > icmp_req=7 ttl=53 time=56.5 ms (DUP!) > 64 bytes from ww-in-f19.1e100.net (209.85.229.19): > icmp_req=7 ttl=53 time=58.2 ms (DUP!) > 64 bytes from ww-in-f19.1e100.net (209.85.229.19): > icmp_req=7 ttl=53 time=59.9 ms (DUP!) > 64 bytes from ww-in-f19.1e100.net (209.85.229.19): > icmp_req=7 ttl=53 time=61.3 ms (DUP!) > 64 bytes from ww-in-f19.1e100.net (209.85.229.19): > icmp_req=7 ttl=53 time=62.9 ms (DUP!) > 64 bytes from ww-in-f19.1e100.net (209.85.229.19): > icmp_req=7 ttl=53 time=63.3 ms (DUP!) > 64 bytes from ww-in-f19.1e100.net (209.85.229.19): > icmp_req=8 ttl=53 time=51.4 ms > ^C > --- gmail.com ping statistics --- > 8 packets transmitted, 8 received, +9 duplicates, 0% packet > loss, time 7011ms > rtt min/avg/max/mdev = 50.285/55.181/63.304/4.219 ms > > Without these, the rt2800usb is looking to be pretty > stellar driver. Further investigation suggests the DUP! packets stem from one specific AP. Different APs seem to have less duplicate packets and overall packet-loss. Its puzzling to me however that the said AP does not produce DUP! packs at all with rt2870sta. I think the problem may be originating from the device's retransmission pattern. The device thinks that certain package(s) were not transmitted correctly and attempts to re-send them again which in essence results in duplicates. Network tests completed with staging and rt2800usb indicate staging slightly outperforms rt2800usb. Also it appears some throughput is lost with rt2800usb. My verdict nevertheless: Drop the staging driver and leave rt2800usb as primary. I'm sure improvements will be made. Plus, having both drivers load together, clash with each other and confuse users isn't desirable, either. Walter