Re: [WT PATCH 4/6] mac80211: Add per-sdata station hash, and sdata hash.

[Felix Fietkau <nbd@openwrt.org>]

On 2013-07-26 6:09 PM, Ben Greear wrote:
> On 07/26/2013 08:38 AM, Felix Fietkau wrote:
>> The global hash (with added vif-addr mixing) not only completely fixes
>> the many-STA-vif case, also has some other advantages compared to the
>> per-sdata hash:
>> - Lookup is easier in setups with multiple AP VLANs
>> - Better cache footprint (especially important for small embedded devices).
>> - You don't need a separate sdata lookup before the sta lookup.
>>
>> I'm not convinced that keeping separate hashes is cleaner. Especially in
>> the AP_VLAN case, ownership is not clear in any way, since there's some
>> overlap between multiple sdata entities (belonging to the same BSS).
> If someone wants to post such a patch, we can run it through our test
> rigs, but I have little time or interest for re-doing the
> hashing code again at this time.  If your approach does fix the performance
> issues we saw, then I'll be more than happy to drop my patch and use
> your method.
I don't have time to create such a patch myself at this point. I just
want to make sure that changes you post don't negatively affect small
embedded devices - and this is where the per-sdata hashing could be
problematic in my opinion.

- Felix