Back in February we disabled iwm firmware Tx retries at lower rates.
This improved MiRA's Tx rate selection because bad rates do actually
look bad, rather than being compensated for by firmware retries.
The result was increased Tx throughput. The original discussion is here:
https://marc.info/?l=openbsd-tech&m=155067514103877&w=2
This approach has a drawback: If a given Tx rate is bad we will lose all
frames sent at that rate. This results in user-visiable packet loss.
The diff below attempts to reduce such user-visible packet loss by
allowing the firmware to retry at lower rates again, but only if MiRA
is not currently probing for a new rate.
I hope this will reduce observable packet loss while still selecting
the best Tx rate. Lightly tested on 8265. More tests welcome.
diff refs/heads/master refs/heads/probing-fixed-rate
blob - dff9f8047f5c0300a4ddde4d9b090f58c28dd8f9 (mode 644)
blob + 8608228c4d05ae6711e55644d50114bacd2e79e3 (mode 600)
--- sys/dev/pci/if_iwm.c
+++ sys/dev/pci/if_iwm.c
@@ -453,6 +453,8 @@ int iwm_run(struct iwm_softc *);
int iwm_run_stop(struct iwm_softc *);
struct ieee80211_node *iwm_node_alloc(struct ieee80211com *);
void iwm_calib_timeout(void *);
+void iwm_setrates_task(void *);
+void iwm_setrates(struct iwm_node *);
int iwm_media_change(struct ifnet *);
void iwm_newstate_task(void *);
int iwm_newstate(struct ieee80211com *, enum ieee80211_state, int);
@@ -4161,13 +4163,21 @@ iwm_rx_tx_cmd_single(struct iwm_softc *sc, struct iwm_
if (txfail)
in->in_mn.txfail += tx_resp->frame_count;
if (ic->ic_state == IEEE80211_S_RUN && !in->ht_force_cck) {
- int otxmcs = ni->ni_txmcs;
-
ieee80211_mira_choose(&in->in_mn, ic, &in->in_ni);
+ /*
+ * If MiRA has chosen a new TX rate we must update
+ * the firwmare's LQ rate table from process context.
+ * ni_txmcs may change again before the task runs so
+ * cache the chosen rate in the iwm_node structure.
+ */
+ if (ni->ni_txmcs != in->chosen_txmcs) {
+ in->chosen_txmcs = ni->ni_txmcs;
+ iwm_add_task(sc, systq, &sc->setrates_task);
+ }
/* Fall back to CCK rates if MCS 0 is failing. */
if (txfail && IEEE80211_IS_CHAN_2GHZ(ni->ni_chan) &&
- otxmcs == 0 && ni->ni_txmcs == 0)
+ in->chosen_txmcs == 0 && ni->ni_txmcs == 0)
iwm_enable_ht_cck_fallback(sc, in);
}
}
@@ -4693,14 +4703,35 @@ iwm_tx_fill_cmd(struct iwm_softc *sc, struct iwm_node
ridx = sc->sc_fixed_ridx;
} else if (ic->ic_fixed_rate != -1) {
ridx = sc->sc_fixed_ridx;
- } else if ((ni->ni_flags & IEEE80211_NODE_HT) && !in->ht_force_cck) {
+ } else if ((ni->ni_flags & IEEE80211_NODE_HT) && !in->ht_force_cck &&
+ ieee80211_mira_is_probing(&in->in_mn)) {
+ /* Keep Tx rate constant while mira is probing. */
ridx = iwm_mcs2ridx[ni->ni_txmcs];
- } else {
+ } else if ((ni->ni_flags & IEEE80211_NODE_HT) && in->ht_force_cck) {
uint8_t rval;
rval = (rs->rs_rates[ni->ni_txrate] & IEEE80211_RATE_VAL);
ridx = iwm_rval2ridx(rval);
if (ridx < min_ridx)
ridx = min_ridx;
+ } else {
+ int i;
+ /* Use firmware rateset retry table. */
+ tx->initial_rate_index = 0;
+ tx->tx_flags |= htole32(IWM_TX_CMD_FLG_STA_RATE);
+ if (ni->ni_flags & IEEE80211_NODE_HT) {
+ ridx = iwm_mcs2ridx[ni->ni_txmcs];
+ return &iwm_rates[ridx];
+ }
+ ridx = (IEEE80211_IS_CHAN_5GHZ(ni->ni_chan)) ?
+ IWM_RIDX_OFDM : IWM_RIDX_CCK;
+ for (i = 0; i < ni->ni_rates.rs_nrates; i++) {
+ if (iwm_rates[i].rate == (ni->ni_txrate &
+ IEEE80211_RATE_VAL)) {
+ ridx = i;
+ break;
+ }
+ }
+ return &iwm_rates[ridx];
}
rinfo = &iwm_rates[ridx];
@@ -6631,6 +6662,9 @@ iwm_run(struct iwm_softc *sc)
/* Start at lowest available bit-rate, AMRR will raise. */
in->in_ni.ni_txrate = 0;
in->in_ni.ni_txmcs = 0;
+ in->chosen_txrate = 0;
+ in->chosen_txmcs = 0;
+ iwm_setrates(in);
timeout_add_msec(&sc->sc_calib_to, 500);
iwm_led_enable(sc);
@@ -6703,6 +6737,16 @@ iwm_calib_timeout(void *arg)
((ni->ni_flags & IEEE80211_NODE_HT) == 0 || in->ht_force_cck) &&
ic->ic_opmode == IEEE80211_M_STA && ic->ic_bss) {
ieee80211_amrr_choose(&sc->sc_amrr, &in->in_ni, &in->in_amn);
+ /*
+ * If AMRR has chosen a new TX rate we must update
+ * the firwmare's LQ rate table from process context.
+ * ni_txrate may change again before the task runs so
+ * cache the chosen rate in the iwm_node structure.
+ */
+ if (ni->ni_txrate != in->chosen_txrate) {
+ in->chosen_txrate = ni->ni_txrate;
+ iwm_add_task(sc, systq, &sc->setrates_task);
+ }
if (in->ht_force_cck) {
struct ieee80211_rateset *rs = &ni->ni_rates;
uint8_t rv;
@@ -6717,6 +6761,139 @@ iwm_calib_timeout(void *arg)
timeout_add_msec(&sc->sc_calib_to, 500);
}
+void
+iwm_setrates_task(void *arg)
+{
+ struct iwm_softc *sc = arg;
+ struct ieee80211com *ic = &sc->sc_ic;
+ struct iwm_node *in = (struct iwm_node *)ic->ic_bss;
+ int s = splnet();
+
+ if (sc->sc_flags & IWM_FLAG_SHUTDOWN) {
+ refcnt_rele_wake(&sc->task_refs);
+ splx(s);
+ return;
+ }
+
+ /* Update rates table based on new TX rate determined by AMRR. */
+ iwm_setrates(in);
+ refcnt_rele_wake(&sc->task_refs);
+ splx(s);
+}
+
+void
+iwm_setrates(struct iwm_node *in)
+{
+ struct ieee80211_node *ni = &in->in_ni;
+ struct ieee80211com *ic = ni->ni_ic;
+ struct iwm_softc *sc = IC2IFP(ic)->if_softc;
+ struct iwm_lq_cmd lqcmd;
+ struct ieee80211_rateset *rs = &ni->ni_rates;
+ int i, ridx, ridx_min, ridx_max, j, sgi_ok = 0, mimo, tab = 0;
+ struct iwm_host_cmd cmd = {
+ .id = IWM_LQ_CMD,
+ .len = { sizeof(lqcmd), },
+ };
+
+ memset(&lqcmd, 0, sizeof(lqcmd));
+ lqcmd.sta_id = IWM_STATION_ID;
+
+ if (ic->ic_flags & IEEE80211_F_USEPROT)
+ lqcmd.flags |= IWM_LQ_FLAG_USE_RTS_MSK;
+
+ if ((ni->ni_flags & IEEE80211_NODE_HT) &&
+ ieee80211_node_supports_ht_sgi20(ni)) {
+ ni->ni_flags |= IEEE80211_NODE_HT_SGI20;
+ sgi_ok = 1;
+ }
+
+ /*
+ * Fill the LQ rate selection table with legacy and/or HT rates
+ * in descending order, i.e. with the node's current TX rate first.
+ * In cases where throughput of an HT rate corresponds to a legacy
+ * rate it makes no sense to add both. We rely on the fact that
+ * iwm_rates is laid out such that equivalent HT/legacy rates share
+ * the same IWM_RATE_*_INDEX value. Also, rates not applicable to
+ * legacy/HT are assumed to be marked with an 'invalid' PLCP value.
+ */
+ j = 0;
+ ridx_min = iwm_rval2ridx(ieee80211_min_basic_rate(ic));
+ mimo = iwm_is_mimo_mcs(in->chosen_txmcs);
+ ridx_max = (mimo ? IWM_RIDX_MAX : IWM_LAST_HT_SISO_RATE);
+ for (ridx = ridx_max; ridx >= ridx_min; ridx--) {
+ uint8_t plcp = iwm_rates[ridx].plcp;
+ uint8_t ht_plcp = iwm_rates[ridx].ht_plcp;
+
+ if (j >= nitems(lqcmd.rs_table))
+ break;
+ tab = 0;
+ if (ni->ni_flags & IEEE80211_NODE_HT) {
+ if (ht_plcp == IWM_RATE_HT_SISO_MCS_INV_PLCP)
+ continue;
+ /* Do not mix SISO and MIMO HT rates. */
+ if ((mimo && !iwm_is_mimo_ht_plcp(ht_plcp)) ||
+ (!mimo && iwm_is_mimo_ht_plcp(ht_plcp)))
+ continue;
+ for (i = in->chosen_txmcs; i >= 0; i--) {
+ if (isclr(ni->ni_rxmcs, i))
+ continue;
+ if (ridx == iwm_mcs2ridx[i]) {
+ tab = ht_plcp;
+ tab |= IWM_RATE_MCS_HT_MSK;
+ if (sgi_ok)
+ tab |= IWM_RATE_MCS_SGI_MSK;
+ break;
+ }
+ }
+ } else if (plcp != IWM_RATE_INVM_PLCP) {
+ for (i = in->chosen_txrate; i >= 0; i--) {
+ if (iwm_rates[ridx].rate == (rs->rs_rates[i] &
+ IEEE80211_RATE_VAL)) {
+ tab = plcp;
+ break;
+ }
+ }
+ }
+
+ if (tab == 0)
+ continue;
+
+ if (iwm_is_mimo_ht_plcp(ht_plcp))
+ tab |= IWM_RATE_MCS_ANT_AB_MSK;
+ else
+ tab |= IWM_RATE_MCS_ANT_A_MSK;
+
+ if (IWM_RIDX_IS_CCK(ridx))
+ tab |= IWM_RATE_MCS_CCK_MSK;
+ lqcmd.rs_table[j++] = htole32(tab);
+ }
+
+ lqcmd.mimo_delim = (mimo ? j : 0);
+
+ /* Fill the rest with the lowest possible rate */
+ while (j < nitems(lqcmd.rs_table)) {
+ tab = iwm_rates[ridx_min].plcp;
+ if (IWM_RIDX_IS_CCK(ridx_min))
+ tab |= IWM_RATE_MCS_CCK_MSK;
+ tab |= IWM_RATE_MCS_ANT_A_MSK;
+ lqcmd.rs_table[j++] = htole32(tab);
+ }
+
+ lqcmd.single_stream_ant_msk = IWM_ANT_A;
+ lqcmd.dual_stream_ant_msk = IWM_ANT_AB;
+
+ lqcmd.agg_time_limit = htole16(4000); /* 4ms */
+ lqcmd.agg_disable_start_th = 3;
+#ifdef notyet
+ lqcmd.agg_frame_cnt_limit = 0x3f;
+#else
+ lqcmd.agg_frame_cnt_limit = 1; /* tx agg disabled */
+#endif
+
+ cmd.data[0] = &lqcmd;
+ iwm_send_cmd(sc, &cmd);
+}
+
int
iwm_media_change(struct ifnet *ifp)
{
@@ -6862,6 +7039,7 @@ iwm_newstate(struct ieee80211com *ic, enum ieee80211_s
ieee80211_mira_cancel_timeouts(&in->in_mn);
iwm_del_task(sc, systq, &sc->ba_task);
iwm_del_task(sc, systq, &sc->htprot_task);
+ iwm_del_task(sc, systq, &sc->setrates_task);
}
sc->ns_nstate = nstate;
@@ -7621,6 +7799,7 @@ iwm_stop(struct ifnet *ifp)
/* Cancel scheduled tasks and let any stale tasks finish up. */
task_del(systq, &sc->init_task);
iwm_del_task(sc, sc->sc_nswq, &sc->newstate_task);
+ iwm_del_task(sc, systq, &sc->setrates_task);
iwm_del_task(sc, systq, &sc->ba_task);
iwm_del_task(sc, systq, &sc->htprot_task);
KASSERT(sc->task_refs.refs >= 1);
@@ -9030,6 +9209,7 @@ iwm_attach(struct device *parent, struct device *self,
timeout_set(&sc->sc_led_blink_to, iwm_led_blink_timeout, sc);
task_set(&sc->init_task, iwm_init_task, sc);
task_set(&sc->newstate_task, iwm_newstate_task, sc);
+ task_set(&sc->setrates_task, iwm_setrates_task, sc);
task_set(&sc->ba_task, iwm_ba_task, sc);
task_set(&sc->htprot_task, iwm_htprot_task, sc);
blob - dd4c70febfbca68cd4208159c5212052e5a811fa
blob + 650e9a562c6b794551c5ef42872465548743d473
--- sys/dev/pci/if_iwmvar.h
+++ sys/dev/pci/if_iwmvar.h
@@ -374,6 +374,7 @@ struct iwm_softc {
struct task init_task; /* NB: not reference-counted */
struct refcnt task_refs;
struct task newstate_task;
+ struct task setrates_task;
enum ieee80211_state ns_nstate;
int ns_arg;
@@ -546,7 +547,9 @@ struct iwm_node {
uint16_t in_color;
struct ieee80211_amrr_node in_amn;
+ int chosen_txrate;
struct ieee80211_mira_node in_mn;
+ int chosen_txmcs;
/* Set in 11n mode if we don't receive ACKs for OFDM frames. */
int ht_force_cck;
blob - 4438af5f63e4868903a2a8b7cc71f89d1868eab0
blob + 96a9f0369085c942fac347fd1091f7d6d076b4f9
--- sys/net80211/ieee80211_mira.c
+++ sys/net80211/ieee80211_mira.c
@@ -1254,3 +1254,9 @@ ieee80211_mira_cancel_timeouts(struct ieee80211_mira_n
for (t = 0; t < nitems(mn->probe_to); t++)
timeout_del(&mn->probe_to[t]);
}
+
+int
+ieee80211_mira_is_probing(struct ieee80211_mira_node *mn)
+{
+ return mn->probing != IEEE80211_MIRA_NOT_PROBING;
+}
blob - 9e6d5e7c3854bf22f877792fe87348b06dbe331d
blob + 9c49d69e5dc760a9e3263e385febd07518eafc61
--- sys/net80211/ieee80211_mira.h
+++ sys/net80211/ieee80211_mira.h
@@ -111,4 +111,7 @@ void ieee80211_mira_cancel_timeouts(struct
ieee80211_m
int ieee80211_mira_get_rts_threshold(struct ieee80211_mira_node *,
struct ieee80211com *, struct ieee80211_node *, size_t);
+/* Indicate whether Tx rates are currently being probed. */
+int ieee80211_mira_is_probing(struct ieee80211_mira_node *);
+
#endif /* _NET80211_IEEE80211_MIRA_H_ */
