Re: Low latency communication over wifi

2015-09-30 Thread Johannes Berg
On Wed, 2015-09-30 at 19:24 +0200, Pavel Machek wrote: > On Mon 2015-09-28 09:41:43, Johannes Berg wrote: > > On Sat, 2015-09-26 at 12:24 +0200, Pavel Machek wrote: > > > > > > That would be equivalent to ping -Q, right? It does not seem to have > > > any effect :-(. I'd expect at least local

Re: Low latency communication over wifi

2015-09-30 Thread Bastian Bittorf
* Pavel Machek [30.09.2015 19:27]: > This should send the second ping to the priority queue based on -Q, > but I don't see an effect against one access point and it seems to > work somehow against second one. Good! you still need to hack/tune minstrel, because a lot of magic

Re: Low latency communication over wifi

2015-09-30 Thread Pavel Machek
On Mon 2015-09-28 09:41:43, Johannes Berg wrote: > On Sat, 2015-09-26 at 12:24 +0200, Pavel Machek wrote: > > > > That would be equivalent to ping -Q, right? It does not seem to have > > any effect :-(. I'd expect at least local machine to use shorter waits > > for medium, and thus drop packets

Re: Low latency communication over wifi

2015-09-28 Thread Bastian Bittorf
* Johannes Berg [28.09.2015 14:00]: > > > # you have to add some magic for matching your data > > > e.g. $IPT -t mangle -I OUTPUT -j DSCP --set-dscp-class CS7 > > > > Again, this is ping -Q equivalent, right? I was doing > > Yes. IMHO this is not the same: you have

Re: Low latency communication over wifi

2015-09-28 Thread Johannes Berg
On Mon, 2015-09-28 at 14:15 +0200, Bastian Bittorf wrote: > * Johannes Berg [28.09.2015 14:00]: > > > > # you have to add some magic for matching your data > > > > e.g. $IPT -t mangle -I OUTPUT -j DSCP --set-dscp-class CS7 > > > > > > Again, this is ping -Q equivalent,

Re: Low latency communication over wifi

2015-09-28 Thread Bastian Bittorf
* Johannes Berg [28.09.2015 14:38]: > Depends what you're measuring, but ping should apply the same DSCP tag > on the response I believe. your are right, I did not know this till yet 8-) (i applied 0xb8 with 'ping -c1 -Q' just for testing) 14:49:52.491925 IP (tos

Re: Low latency communication over wifi

2015-09-26 Thread Pavel Machek
Hi! > > (I could use Intel 3945ABG-based card instead, but I figured out > > ath5k might be easier to hack?) > > > > Is there way to manipulate type of service from userland to get > > similar behaviour without patching kernel? > > If your AP has WMM/QoS then you can use

Re: Low latency communication over wifi

2015-09-23 Thread Bastian Bittorf
* Pavel Machek [23.09.2015 13:38]: > Is there way to manipulate type of service from userland to get > similar behaviour without patching kernel? yes, iptables DSCP / DiffServ / Differentiated Services Field # you have to add some magic for matching your data e.g. $IPT -t mangle

ath5k filling logs (was Re: Low latency communication over wifi)

2015-09-23 Thread Pavel Machek
Hi! > I hacked qcu.c to limit latencies: > > qi->tqi_cw_min = ath5k_cw_validate(0); > qi->tqi_cw_max = ath5k_cw_validate(20); > > ...but I don't think it did what I wanted. What am I missing? > > (I could use Intel 3945ABG-based card instead, but I figured out ath5k > might

Low latency communication over wifi

2015-09-23 Thread Pavel Machek
Hi! I'm trying to transfer some audio data over wifi. Latency constrains are such that if it would took more than 20msec to wait for transmission, the packet should be dropped instead, and new one should be transmitted. My final hardware contains CSR6026 chip, but drivers are way too ugly, I

Re: Low latency communication over wifi

2015-09-23 Thread Johannes Berg
On Wed, 2015-09-23 at 13:03 +0200, Pavel Machek wrote: > Hi! > > I'm trying to transfer some audio data over wifi. Latency constrains > are such that if it would took more than 20msec to wait for > transmission, the packet should be dropped instead, and new one > should be transmitted. This is