Subject: Re: Thoughts about mac80211 client PS implementation
From: Johannes Berg <johannes@sipsolutions.net>
To: Kalle Valo <kalle.valo@nokia.com>
Cc: linux-wireless@vger.kernel.org
In-Reply-To: <1225969259.3619.202.camel@johannes.berg> (sfid-20081106_120106_811231_EB10DE82)
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Date: Fri, 07 Nov 2008 17:06:24 +0100
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On Thu, 2008-11-06 at 12:00 +0100, Johannes Berg wrote:

> > > Maybe we don't want to disable PS for a single frame though
> >=20
> > Actually I think we do. The reason why I'm interested in dynamic PS is
> > the receive latency (transmit latency minimal is in practise). For
> > example, let's think about DNS request. In the best scenario only one
> > frame is transmitted, and if we don't come out receiving the reply to
> > the dns request will take a long time. If DTIM is 3 and beacon
> > interval 100 ms, the RTT for the DNS request/reply would be 300 ms.
> > That's a long delay to a case where user has pressed a link in the
> > browser and the browser starts to load a web page.
>=20
> Good point. So set my M to 1 and N to 0 ;) Well, in that case you don't
> need a timer at all but can just schedule the work right away.

Another thought I just had: you could catch the frame in
subif_start_xmit, stop the master interface queues, xmit the frame to
the master interface, schedule the PS off work, and after that turns PS
on you wake the master queues.

johannes

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