From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from he.sipsolutions.net ([78.46.109.217]:46198 "EHLO sipsolutions.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754545Ab1BOMNL (ORCPT ); Tue, 15 Feb 2011 07:13:11 -0500 Subject: Re: [PATCH 4/5] iwlwifi: auto-tune tx queue size to minimize latency From: Johannes Berg To: Nathaniel Smith Cc: linville@tuxdriver.com, linux-wireless@vger.kernel.org, wey-yi.w.guy@intel.com, ilw@linux.intel.com In-Reply-To: References: <1297619803-2832-1-git-send-email-njs@pobox.com> <1297619803-2832-5-git-send-email-njs@pobox.com> <1297685871.3785.39.camel@jlt3.sipsolutions.net> Content-Type: text/plain; charset="UTF-8" Date: Tue, 15 Feb 2011 13:13:06 +0100 Message-ID: <1297771986.3935.9.camel@jlt3.sipsolutions.net> Mime-Version: 1.0 Sender: linux-wireless-owner@vger.kernel.org List-ID: On Mon, 2011-02-14 at 13:58 -0800, Nathaniel Smith wrote: > > This sounds nice -- but couldn't it just as well be implemented in > > mac80211, at least for most devices (that have accurate TX status > > reporting)? > > I don't know. I take it you're imagining a scheme where mac80211 keeps > a hash table or similar of all packets that have been queued to the > device, and does its own tx rate estimation and calls start/stop_queue > as needed? If that works, then it would be lovely. (Heck, it should > probably go in the generic net layer eventually; ethernet cards have > the same problem.) Well, no, why would it keep a hash table?? And no -- it can't be done in the generic net layer. mac80211 has the advantage that TX status is reported back, so it could pretty accurately know how many frames are queued up -- more generically this cannot be done. But since it's not perfectly accurate right now, it may not be the best idea to do this at this time. johannes