Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753430Ab1DNFRR (ORCPT ); Thu, 14 Apr 2011 01:17:17 -0400 Received: from mail-bw0-f46.google.com ([209.85.214.46]:40418 "EHLO mail-bw0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752908Ab1DNFRP (ORCPT ); Thu, 14 Apr 2011 01:17:15 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=message-id:date:from:user-agent:mime-version:to:cc:subject :references:in-reply-to:content-type:content-transfer-encoding; b=CUKNH6TncAeJyyzSFFeYUjS5NAdwAjSYNTexVhNuWOZlSxmc0JYRiYGYVETEYo07rP MKSf4rbHcu649Afuk/RkwEYr3olJh2vBfkKRhBEbRyuSC17ZoVySaBVNvJjZlFWck4nY 668QdaWj5/YR/2BAXJzFHjIeOeotK/TWKy3IA= Message-ID: <4DA68354.4060603@gmail.com> Date: Thu, 14 Apr 2011 09:17:08 +0400 From: Igor Plyatov User-Agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.2.14) Gecko/20110223 Thunderbird/3.1.8 MIME-Version: 1.0 To: Justin Piszcz CC: Daniel Halperin , Ivo Van Doorn , linux-usb@vger.kernel.org, linux-wireless@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: 2.6.38: rt2800usb: high latency (1000ms)? References: In-Reply-To: Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3859 Lines: 101 Hi! > On Wed, 13 Apr 2011, Daniel Halperin wrote: > >> On Wed, Apr 13, 2011 at 10:57 AM, Justin Piszcz >> wrote: >>> Hi, >>> >>> When powersave is enabled, it is very jumpy, I've used satellite comms >>> before >>> and (~600ms-1200ms was more smooth) as it did not jump around as >>> much. The >>> application is just a standalone desktop with minimal activity for the >>> majority >>> of the time, maybe thats why.. >>> >>> With powersave disabled, I now see 0% packet loss (802.11n) and low >>> ping >>> times, this looks like the proper solution for the wireless USB >>> device I >>> am using. By the way, is it possible/are there wireless USB devices >>> out >>> there >>> that support wake on wireless lan (WOWL? >>> >>> Your ping command with power off: >>> 1408 bytes from server (192.168.1.2): icmp_req=539 ttl=64 time=1.07 ms >>> 1408 bytes from server (192.168.1.2): icmp_req=540 ttl=64 time=1.31 ms >>> 1408 bytes from server (192.168.1.2): icmp_req=541 ttl=64 time=1.07 ms >>> 1408 bytes from server (192.168.1.2): icmp_req=542 ttl=64 time=1.26 ms >>> >>> Your ping command with power on: >>> 1408 bytes from server (192.168.1.2): icmp_req=649 ttl=64 time=1.80 ms >>> 1408 bytes from server (192.168.1.2): icmp_req=650 ttl=64 time=1.85 ms >>> 1408 bytes from server (192.168.1.2): icmp_req=651 ttl=64 time=2.86 ms >>> 1408 bytes from server (192.168.1.2): icmp_req=652 ttl=64 time=1.46 ms >>> >>> You are correct, if there is a lot of traffic, its good, but if the >>> system >>> is relatively idle and all that's going on is an SSH session, there is >>> horrible >>> latency. >> >> Gotcha. I might still look around in the network stack and/or driver >> and see what the time constants are. For instance: >> >> (1) What is the AP's beacon period and DTIM? Typical values are 100 >> TUs for beacons (102.4 ms) and 2 for DTIM (2 beacons per power-save >> wakeup) which should imply a mean of 100 and max of 200 ms delay even >> on pings. > I am using a WNDR3700 with default settings in terms of beacons/etc. No > issues with any device (laptop, computer, etc (in windows)), I have two > wireless USB adapters (bought two) and in Windows, no problems, I > don't think > it is the WNDR3700. As far as linux/wpa-supplicant, using default > settings. > > >> >> (2) How long does the client wait after waking up to go back to sleep? >> It should be at least a few seconds. For ssh, then, you should see >> something like a 100-200 ms delay for the first key and then nothing >> at all unless you stop typing for a bit. > It lags with each word I type, it is terrible. If I run something like > dmesg or ps auxww, the entire session freezes for 5-10 seconds before it > comes back. Yes, it's terrible. I have the same problems with ping and ssh with latest GIT linux on my ARM platform and two different USB Wi-Fi adapters based on RT3070 chipset ("D-Link DWA-125" and "Qcom LR802UKN3"). > >> >> I'm SSHing over a Wi-Fi link that uses power save right this second, >> and have for years. It's not generally an issue, I suspect something >> worse is going on. > Maybe the wireless usb adapters do not function well in Linux with > power save > on. > > I bought them awhile ago, they had the highest reviews, and in Windows, > they did do 10-15MiB/s, in Linux, I see ~4.6MiB/s (but that was with > power save on) about the same, 4.5MiB/s. > http://www.amazon.com/Medialink-Wireless-Adapter-802-11n-Compatible/dp/B002RM08RE > > > 100+0 records in > 100+0 records out > 104857600 bytes (105 MB) copied, 23.2803 s, 4.5 MB/s > > Justin. Best regards! -- Igor Plyatov -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/