Message-ID: <51F247C1.3090702@openwrt.org> (sfid-20130726_115638_698029_DD1385A2)
Date: Fri, 26 Jul 2013 11:56:17 +0200
From: Felix Fietkau <nbd@openwrt.org>
MIME-Version: 1.0
To: Johannes Berg <johannes@sipsolutions.net>
CC: Ben Greear <greearb@candelatech.com>,
	linux-wireless@vger.kernel.org
Subject: Re: [WT PATCH 4/6] mac80211: Add per-sdata station hash, and sdata
 hash.
References: <1372546738-25827-1-git-send-email-greearb@candelatech.com>   <1372546738-25827-4-git-send-email-greearb@candelatech.com>   (sfid-20130630_005944_514926_D21D8724) <1373532936.8201.5.camel@jlt4.sipsolutions.net>  <51DECF5B.7040002@candelatech.com> <1374828780.8248.24.camel@jlt4.sipsolutions.net>
In-Reply-To: <1374828780.8248.24.camel@jlt4.sipsolutions.net>
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Sender: linux-wireless-owner@vger.kernel.org

On 2013-07-26 10:53 AM, Johannes Berg wrote:
> On Thu, 2013-07-11 at 08:29 -0700, Ben Greear wrote:
> 
>> > I also don't like maintaining two separate hash tables and all that.
>> >
>> > I'd reconsider if you actually remove the hash entirely, but that'll be
>> > tricky to walk the station list and will quite possibly make the RX path
>> > there more expensive?
>> 
>> Remove local->sta_hash ?
> 
> To be honest, I'm undecided. Yes, I was thinking that, but I also think
> having a huge hashtable like that for each virtual interface is way
> overkill, in particular for station interfaces that usually have one
> peer (the AP) and maybe a few TDLS peers. Or P2P-Device interfaces that
> have no peers at all ...
> 
> I don't see a good way to improve the hash either, since we don't always
> (e.g. in RX path) have the interface address.
How about mixing in the interface address into the hash. Theoretically
you should always have that available, even in the rx path. Multicast
data packets contain the BSSID, so you can get the address from there.
You just need to be careful about checking the DS bits to figure out
which address to use ;)
I think this is a much better solution than duplicating the hash, or
moving it into sdata entirely.

- Felix