Re: [OpenWrt-Devel] Q: mac80211: default distance-settings 0

2014-10-07 Thread Bastian Bittorf
* Felix Fietkau n...@openwrt.org [07.10.2014 13:40]:
 On 2014-10-07 08:15, Bastian Bittorf wrote:
  because 0 seems to be a valid value:
 0 does not imply dynamic ACK, it is simply the minimum value.
 Enabling dynack by default would be a bad idea.

what does 0 mean? the wiki says: 0 meters away, so a short
ack-timeout is used, or is '0' something special, eg. driver default?

i tested a p2p/longshot here, where both stations are 350m away, but
invoking on both sides:

iw phy phy0 set distance 350

shows, that the link gets really worse, also with 500 or 2000.
can't it be changed during runtime?

bye, bastian
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Re: [OpenWrt-Devel] Q: mac80211: default distance-settings 0

2014-10-07 Thread Bill
Message: 1 Date: Tue, 7 Oct 2014 17:17:40 +0200 From: Bastian Bittorf 
bitt...@bluebottle.com To: mailinglist 
openwrt-devel@lists.openwrt.org Subject: Re: [OpenWrt-Devel] Q: 
mac80211: default distance-settings 0 Message-ID: 
20141007151740.gj29...@medion.lan Content-Type: text/plain; 
charset=us-ascii * Felix Fietkau n...@openwrt.org [07.10.2014 13:40]:

On 2014-10-07 08:15, Bastian Bittorf wrote:

because 0 seems to be a valid value:

0 does not imply dynamic ACK, it is simply the minimum value.
Enabling dynack by default would be a bad idea.

what does 0 mean? the wiki says: 0 meters away, so a short
ack-timeout is used, or is '0' something special, eg. driver default?

i tested a p2p/longshot here, where both stations are 350m away, but
invoking on both sides:

iw phy phy0 set distance 350

shows, that the link gets really worse, also with 500 or 2000.
can't it be changed during runtime?

bye, bastian


--


Bastian-

I was doing some tests last week using an access point running a CC 
trunk build.


I remembered that the right value was supposed to be the actual 
distance*2 (essentially, counting out and back distance).


My test link was at about 8 km. I tried a number of values (on both AP 
and client) - distance=15000, 1, and then just backed it off by 1000 
incrementally - and the throughput (measured with iperf) got better as I 
went down in distance. The optimal throughput was at distance=5000, 
where it was about 5 Mbps. However, when I set it at distance=4000, 
suddenly throughput went to less than 200 Kbps.


Real world observations, FWIW...

-Bill
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