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From: Johannes Berg <johannes@sipsolutions.net>
To: Nathaniel Smith <njs@pobox.com>
Cc: linville@tuxdriver.com, linux-wireless@vger.kernel.org,
	wey-yi.w.guy@intel.com, ilw@linux.intel.com
Subject: Re: [PATCH 4/5] iwlwifi: auto-tune tx queue size to minimize latency
Date: Tue, 15 Feb 2011 13:13:06 +0100	[thread overview]
Message-ID: <1297771986.3935.9.camel@jlt3.sipsolutions.net> (raw)
In-Reply-To: <AANLkTinuvxEuuz3-xWkhQ1fA8s7QumJHJQKpd1C48CV1@mail.gmail.com>

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


  reply	other threads:[~2011-02-15 12:13 UTC|newest]

Thread overview: 48+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2011-02-13 17:56 [PATCH 0/5] iwlwifi: Auto-tune tx queue size to maintain latency under load Nathaniel J. Smith
2011-02-13 17:56 ` [PATCH 1/5] iwlwifi: Simplify tx queue management Nathaniel J. Smith
2011-02-14  9:57   ` Johannes Berg
2011-02-14 22:17     ` Nathaniel Smith
2011-02-14 22:45       ` wwguy
2011-02-15  0:15         ` Dave Täht
2011-02-16  9:16         ` Stanislaw Gruszka
2011-02-16 14:41           ` John W. Linville
2011-02-16 15:13             ` wwguy
2011-02-15 12:11       ` Johannes Berg
2011-02-14 15:33   ` wwguy
2011-02-13 17:56 ` [PATCH 2/5] iwlwifi: Convert the tx queue high_mark to an atomic_t Nathaniel J. Smith
2011-02-14 12:16   ` Johannes Berg
2011-02-14 22:35     ` Nathaniel Smith
2011-02-15 12:08       ` Johannes Berg
2011-02-15 17:37         ` Nathaniel Smith
2011-02-13 17:56 ` [PATCH 3/5] iwlwifi: Invert the sense of the queue high_mark Nathaniel J. Smith
2011-02-13 17:56 ` [PATCH 4/5] iwlwifi: auto-tune tx queue size to minimize latency Nathaniel J. Smith
2011-02-14 12:17   ` Johannes Berg
2011-02-14 21:58     ` Nathaniel Smith
2011-02-15 12:13       ` Johannes Berg [this message]
2011-02-15 15:03         ` John W. Linville
2011-02-16  8:59           ` Johannes Berg
2011-02-15 17:31         ` Nathaniel Smith
2011-02-14 15:46   ` wwguy
2011-02-13 17:56 ` [PATCH 5/5] iwlwifi: make current tx queue sizes visible in debugfs Nathaniel J. Smith
2011-02-14  0:32 ` [PATCH 0/5] iwlwifi: Auto-tune tx queue size to maintain latency under load Julian Calaby
2011-02-14  3:28   ` Nathaniel Smith
2011-02-16 15:50 ` John W. Linville
2011-02-16 23:08   ` Nathaniel Smith
2011-02-16 23:42     ` wwguy
2011-02-17  1:49 ` [RFC] mac80211: implement eBDP algorithm to fight bufferbloat John W. Linville
2011-02-17  3:31   ` Ben Greear
2011-02-17  4:26   ` Nathaniel Smith
2011-02-17  8:31   ` Johannes Berg
2011-02-18 21:21   ` [RFC v2] " John W. Linville
2011-02-19  3:44     ` Nathaniel Smith
2011-02-21 18:47       ` John W. Linville
2011-02-21 23:26         ` Nathaniel Smith
2011-02-23 22:28           ` John W. Linville
2011-02-25 18:21             ` Nathaniel Smith
2011-02-25 18:27               ` Nathaniel Smith
2011-02-20  0:37     ` Nathaniel Smith
2011-02-21 18:52       ` John W. Linville
2011-02-21 15:28     ` Johannes Berg
2011-02-21 19:06       ` John W. Linville
2011-02-21 20:26         ` Tianji Li
2011-02-28 13:07         ` Johannes Berg

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