[Madwifi-devel] binary expo backoff in madwifi From: meihsual - 2005-03-09 00:45 Attachments: Message as HTML ```Hello experts, I have a question about MAC retry in madwifi. Hopefully someone can help me clarify this :-) As you know, Amrr uses 4 retry counts to adapt the sending rate (amn_tx_try?_cnt) . For each retry, does that mean a "physical" retry? Or a retry here means a count that 7 (default value of 802.11) retransmissions have been issues? Thanks in advance Amy ```
 Re: [Madwifi-devel] binary expo backoff in madwifi From: Mathieu Lacage - 2005-03-25 16:13 ```On Tue, 2005-03-08 at 19:45 -0500, meihsual wrote: > As you know, Amrr uses 4 retry counts to adapt the sending rate > (amn_tx_try?_cnt) . For each retry, does that mean a =E2=80=9Dphysical=E2= =80=9D retry? I don't know what a "physical" retry is. > Or a retry here means a count that 7 (default value of 802.11) > retransmissions have been issues? amrr (at least, the version I wrote) performs at most 3 retransmissions or a total of 4 transmissions with 4 different rates (one rate for each transmission). The tryX_cnt tell you how many times the transmission number X was used.=20 If two packets require 2 transmissions, you have: try0_cnt =3D 2 try1_cnt =3D 2 If one packet requires one transmission and another requires 3 transmissions, you have: try0_cnt =3D 2 try1_cnt =3D 1 try2_cnt =3D 1 The relevant code is: void ath_rate_tx_complete(struct ath_softc *sc, struct ath_node *an, const struct ath_desc *ds) { struct amrr_node *amn =3D ATH_NODE_AMRR(an); int sr =3D ds->ds_txstat.ts_shortretry; int lr =3D ds->ds_txstat.ts_longretry; int retry_count =3D sr + lr; = = =20 amn->amn_tx_try0_cnt++; if (retry_count =3D=3D 1) { amn->amn_tx_try1_cnt++; } else if (retry_count =3D=3D 2) { amn->amn_tx_try1_cnt++; amn->amn_tx_try2_cnt++; } else if (retry_count =3D=3D 3) { amn->amn_tx_try1_cnt++; amn->amn_tx_try2_cnt++; amn->amn_tx_try3_cnt++; } else if (retry_count > 3) { amn->amn_tx_try1_cnt++; amn->amn_tx_try2_cnt++; amn->amn_tx_try3_cnt++; amn->amn_tx_failure_cnt++; } } If you have further questions about amrr, please CC me because I very rarely read the mailing list. regards, Mathieu --=20 ```