hi! ok. 1ms is a long amount of time. Maybe use the tracing feature in ath9k and/or add some debugging in the RX and TX paths that log the TSC (system clock) value whenever the RX path and TX queue path fires?
See if it's scheduling things to the hardware quickly or not. It may be something really silly like context switching between the RX and TX threads of the driver. -adrian On 28 June 2016 at 19:05, Cesar <caesa...@163.com> wrote: > Dear Adrian Chadd, > > Thanks for your reply. It's correct that USB may introduce some delays, but > in our experiment we use mini-pcie devices indeed... > > Cesar > > > > > > > > At 2016-06-29 04:05:32, "Adrian Chadd" <adr...@freebsd.org> wrote: >>Hi, >> >>can you try this using pci/pcie devices instead of USB? There may be >>USB scheduling things in the way. >> >>On 27 June 2016 at 20:55, Cesar <caesa...@163.com> wrote: >>> Hello all, >>> We’ve recently tried to test packet injection performace in ath9k monitor >>> mode. We set 2 laptops in monitor mode , PC 1 send a 500 Byte packets >>> out, >>> and PC 2 return a 500 Bytes packet back at once when it receives the >>> packet >>> of PC 1. Then we measured the RTT time and found it's about 1000us !!! >>> >>> Test environment: >>> NIC: AR9287 >>> driver: ath9k >>> system: ubuntu 14.04 with kernel 3.14.57 >>> send rate : at a fixed rate 54Mb >>> >>> >>> We tried to send packets as "low" as possible in driver stack, and we're >>> sure that we disabled the CCA and backoff using flags below: >>> >>> AR_DIAG_FORCE_CH_IDLE_HIGH >>> AR_DIAG_IGNORE_VIRT_CS >>> AR_D_GBL_IFS_MISC_IGNORE_BACKOFF >>> >>> besides we change the aifs to 1 and cwmin cwmax to 0 in ath_txq_setup to >>> ensure there's no backoff. we even put our laptaps to a underground >>> garage >>> where channel is almost clean.But the test results is still about >>> 1000us.... >>> >>> We've been stucked for serveral months, Any suggestion? >>> Any feedback welcome... >>> Thnkz in advance!!! >>> >>> Cesar >>> >>> >>> >>> >>> >>> >>> >>> _______________________________________________ >>> ath9k-devel mailing list >>> ath9k-devel@lists.ath9k.org >>> https://lists.ath9k.org/mailman/listinfo/ath9k-devel >>> > > > > _______________________________________________ ath9k-devel mailing list ath9k-devel@lists.ath9k.org https://lists.ath9k.org/mailman/listinfo/ath9k-devel
