On 04/03/2013 05:46 AM, Johannes Berg wrote:
On Tue, 2013-04-02 at 16:45 -0700, Ben Greear wrote:
I notice that the rx logic currently walks through all stations when a NIC receives
a packet.
With the attached patch, total TCP download throughput goes from 70Mbps to 190Mbps on
my test system (Atom 1.6Ghz) with 50 station VIFs receiving TCP data streams.
The basic idea is to hash on the VIF addr (ie, what you see in 'ifconfig wlan0' as MAC
address), and then look up stations using the hdr->addr1 in the rx logic.
The attached patch probably breaks monitor interfaces and other VIFs other than AP and
STA. It also changes the behaviour of PROMISC, but I'm not sure that is bad (is
the old behaviour needed for anything useful?)
I'm thinking to store a count of all VIF types on a radio, and make
this hash code only be enabled when only STA and AP exist. Maybe later optimize
so we can quickly find monitor or other VIF types to handle them properly.
Comments and suggestions are welcome.
Hmmm. I'm not really convinced this will make sense upstream. I'm kinda
fine with the single-station cache, but maintaining a whole other hash
table seems too much overhead for every use case but yours.
Yeah, aside from multiple stations, I'm not sure it helps anything. It would
require a different scheme to help with multiple VAP I think, and I'm not
sure there are any other multi-vif use cases out there...
+ /* If we have only station and AP interfaces, then hash on
+ * the destination MAC (ie, local sdata MAC). Could add other
+ * device types as well, perhaps. This changes 'promisc' behaviour,
+ * but not sure that is a bad thing.
+ */
+ if (!is_multicast_ether_addr(hdr->addr1)) {
+ sta = sta_info_get_by_vif(local, hdr->addr1);
AFAICT, this is also wrong for TDLS and other cases where we might
receive a frame that's not from the AP, even if it's only by accident or
from an attacker.
I think patch is probably wrong for any VIF that can be associated with more than
one station (such as APs). I'm going to re-work the vhash to only include
Station VIFS and see how that works for my test case.
Thanks,
Ben
--
Ben Greear <greearb@xxxxxxxxxxxxxxx>
Candela Technologies Inc http://www.candelatech.com
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