Date: Wed, 9 Jan 2013 12:03:44 +0100
From: Stanislaw Gruszka <sgruszka@redhat.com>
To: Seth Forshee <seth.forshee@canonical.com>
Cc: Johannes Berg <johannes@sipsolutions.net>,
	linux-wireless@vger.kernel.org
Subject: Re: [RFC 3/3] mac80211: Disable off-channel powersave when software
 scans are suspended
Message-ID: <20130109110343.GA13544@redhat.com> (sfid-20130109_120355_154694_E1B1CA18)
References: <1357668645-5101-1-git-send-email-seth.forshee@canonical.com>
 <1357668645-5101-4-git-send-email-seth.forshee@canonical.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
In-Reply-To: <1357668645-5101-4-git-send-email-seth.forshee@canonical.com>
Sender: linux-wireless-owner@vger.kernel.org

Hi

On Tue, Jan 08, 2013 at 12:10:45PM -0600, Seth Forshee wrote:
> Leaving powersave enabled while the scan is suspended requires the use
> of PS-Poll to retrieve frames buffered at the AP. PS-Poll isn't a very
> efficient means of data transfer and may not even work with drivers not
> supporting powersave. These problems can largely be avoided by simply
> disabling off-channel powersave when the scan is suspended and enabling
> it again when returning to off-channel operation.
> 
> The results of this change are fantastic. Previously when using iperf I
> would see greatly decreased throughput (often dropping to 0 bits/sec for
> several seconds) and very high packet loss during software scans. This
> patch completely eliminates the packet loss and reduces the loss in
> throughput to very reasonable levels.

I posted a patch, which remove offchannel_ps_disable argument from
ieee80211_offchannel_return, since there were possible AP and STA power
save state mismash:

http://marc.info/?l=linux-wireless&m=135601089321822&w=2

It should give the same effect on performance as this patch.

Thanks
Stanislaw