Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932874Ab1DMQ0i (ORCPT ); Wed, 13 Apr 2011 12:26:38 -0400 Received: from mail-bw0-f46.google.com ([209.85.214.46]:54664 "EHLO mail-bw0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932632Ab1DMQ0E convert rfc822-to-8bit (ORCPT ); Wed, 13 Apr 2011 12:26:04 -0400 MIME-Version: 1.0 In-Reply-To: References: From: Daniel Halperin Date: Wed, 13 Apr 2011 09:25:42 -0700 Message-ID: Subject: Re: 2.6.38: rt2800usb: high latency (1000ms)? To: Justin Piszcz Cc: Ivo Van Doorn , linux-usb@vger.kernel.org, linux-wireless@vger.kernel.org, linux-kernel@vger.kernel.org Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2131 Lines: 34 Ugh! Couldn't you configure the stupid mailing list filter to only drop rich text mails that have [PATCH or [RFC or [RFT in the subject, e.g.? Original mail below. (sorry for the resend, Justin and Ivo). Dan On Wed, Apr 13, 2011 at 9:23 AM, Daniel Halperin wrote: > > On Wed, Apr 13, 2011 at 9:01 AM, Justin Piszcz wrote: >>> >>> Can you try disabling powersaving? >>> iwconfig wlan0 power off >>> >> Wow! That was it, now its interactive again. >> >> 64 bytes from wireless-host (192.168.1.2): icmp_req=1 ttl=64 time=0.581 ms >> 64 bytes from wireless-host (192.168.1.2): icmp_req=2 ttl=64 time=0.647 ms >> >> Thanks, so its recommend to keep this off then, can that be set as the driver default? >> > > That's a bad idea, what you're seeing is likely completely a red herring.?Wi-Fi power saving mode saves energy by putting the RF hardware most of the time. This is a Good Thing. > Power save is designed to kick in only when the load is very slow; the client's network stack should automatically disable power save during times of high load, e.g., during a download or a VoIP call. You should run some tests to see if this is actually occurring; there may be a bug in the rtl implementation. > The real problem here is that your ping test has invalid assumptions. One packet/second is not enough load to disable Wi-Fi power save, so you should not see interactive ping times. Again, this is a good thing and something I doubt you want to disable! (Assuming that RTL's implementation isn't fundamentally broken elsewhere) It certainly should NOT be the driver default. > Try again with sudo ping -i 0.01 -s 1400 (e.g., to ping with large packets every 10 ms); this should probably trigger the logic that automatically disables the power saving mode. Or try pinging while doing a 1 Mbit UDP transfer (e.g., with iperf). > Dan -- 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/