Move some code out of rc80211_simple since it's probably needed for all rate
selection algorithms. While at it, clean up the rate_control_get_rate()
interface.
Signed-off-by: Mattias Nissler <[email protected]>
---
net/mac80211/ieee80211_rate.c | 47 ++++++++++++++++++++++++++++
net/mac80211/ieee80211_rate.h | 68 ++++++++++++++++++++++++++---------------
net/mac80211/ieee80211_sta.c | 13 +++-----
net/mac80211/rc80211_simple.c | 64 ++++++--------------------------------
net/mac80211/tx.c | 42 +++++++++++--------------
5 files changed, 124 insertions(+), 110 deletions(-)
diff --git a/net/mac80211/ieee80211_rate.c b/net/mac80211/ieee80211_rate.c
index 7254bd6..a2f8d64 100644
--- a/net/mac80211/ieee80211_rate.c
+++ b/net/mac80211/ieee80211_rate.c
@@ -146,6 +146,53 @@ static void rate_control_release(struct kref *kref)
kfree(ctrl_ref);
}
+void rate_control_get_rate(struct net_device *dev,
+ struct ieee80211_hw_mode *mode, struct sk_buff *skb,
+ struct rate_selection *sel)
+{
+ struct ieee80211_local *local = wdev_priv(dev->ieee80211_ptr);
+ struct rate_control_ref *ref = local->rate_ctrl;
+ struct ieee80211_sub_if_data *sdata;
+ struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) skb->data;
+ struct sta_info *sta = sta_info_get(local, hdr->addr1);
+ int i;
+ u16 fc;
+
+ memset(sel, 0, sizeof(struct rate_selection));
+
+ /* Send management frames and broadcast/multicast data using lowest
+ * rate. */
+ fc = le16_to_cpu(hdr->frame_control);
+ if ((fc & IEEE80211_FCTL_FTYPE) != IEEE80211_FTYPE_DATA ||
+ (hdr->addr1[0] & 0x01))
+ sel->rate = rate_lowest(local, mode, sta);
+
+ /* If a forced rate is in effect, select it. */
+ sdata = IEEE80211_DEV_TO_SUB_IF(dev);
+ if (sdata->bss && sdata->bss->force_unicast_rateidx > -1)
+ sel->rate = &mode->rates[sdata->bss->force_unicast_rateidx];
+
+ /* If we haven't found the rate yet, ask the rate control algo. */
+ if (!sel->rate)
+ ref->ops->get_rate(ref->priv, dev, mode, skb, sel);
+
+ /* Select a non-ERP backup rate. */
+ if (!sel->nonerp) {
+ for (i = 0; i < mode->num_rates - 1; i++) {
+ struct ieee80211_rate *rate = &mode->rates[i];
+ if (sel->rate->rate < rate->rate)
+ break;
+
+ if (rate_supported(sta, mode, i) &&
+ !(rate->flags & IEEE80211_RATE_ERP))
+ sel->nonerp = rate;
+ }
+ }
+
+ if (sta)
+ sta_info_put(sta);
+}
+
struct rate_control_ref *rate_control_get(struct rate_control_ref *ref)
{
kref_get(&ref->kref);
diff --git a/net/mac80211/ieee80211_rate.h b/net/mac80211/ieee80211_rate.h
index 2368813..ceb7783 100644
--- a/net/mac80211/ieee80211_rate.h
+++ b/net/mac80211/ieee80211_rate.h
@@ -18,31 +18,24 @@
#include "ieee80211_i.h"
#include "sta_info.h"
-#define RATE_CONTROL_NUM_DOWN 20
-#define RATE_CONTROL_NUM_UP 15
-
-
-struct rate_control_extra {
- /* values from rate_control_get_rate() to the caller: */
- struct ieee80211_rate *probe; /* probe with this rate, or NULL for no
- * probing */
+struct rate_selection {
+ /* Selected transmission rate */
+ struct ieee80211_rate *rate;
+ /* Non-ERP rate to use if mac80211 decides it cannot use an ERP rate */
struct ieee80211_rate *nonerp;
-
- /* parameters from the caller to rate_control_get_rate(): */
- struct ieee80211_hw_mode *mode;
- u16 ethertype;
+ /* probe with this rate, or NULL for no probing */
+ struct ieee80211_rate *probe;
};
-
struct rate_control_ops {
struct module *module;
const char *name;
void (*tx_status)(void *priv, struct net_device *dev,
struct sk_buff *skb,
struct ieee80211_tx_status *status);
- struct ieee80211_rate *(*get_rate)(void *priv, struct net_device *dev,
- struct sk_buff *skb,
- struct rate_control_extra *extra);
+ void (*get_rate)(void *priv, struct net_device *dev,
+ struct ieee80211_hw_mode *mode, struct sk_buff *skb,
+ struct rate_selection *sel);
void (*rate_init)(void *priv, void *priv_sta,
struct ieee80211_local *local, struct sta_info *sta);
void (*clear)(void *priv);
@@ -75,6 +68,9 @@ void ieee80211_rate_control_unregister(struct rate_control_ops *ops);
* first available algorithm. */
struct rate_control_ref *rate_control_alloc(const char *name,
struct ieee80211_local *local);
+void rate_control_get_rate(struct net_device *dev,
+ struct ieee80211_hw_mode *mode, struct sk_buff *skb,
+ struct rate_selection *sel);
struct rate_control_ref *rate_control_get(struct rate_control_ref *ref);
void rate_control_put(struct rate_control_ref *ref);
@@ -88,15 +84,6 @@ static inline void rate_control_tx_status(struct ieee80211_local *local,
}
-static inline struct ieee80211_rate *
-rate_control_get_rate(struct ieee80211_local *local, struct net_device *dev,
- struct sk_buff *skb, struct rate_control_extra *extra)
-{
- struct rate_control_ref *ref = local->rate_ctrl;
- return ref->ops->get_rate(ref->priv, dev, skb, extra);
-}
-
-
static inline void rate_control_rate_init(struct sta_info *sta,
struct ieee80211_local *local)
{
@@ -142,6 +129,37 @@ static inline void rate_control_remove_sta_debugfs(struct sta_info *sta)
#endif
}
+static inline int
+rate_supported(struct sta_info *sta, struct ieee80211_hw_mode *mode, int index)
+{
+ return (sta == NULL || sta->supp_rates & BIT(index)) &&
+ (mode->rates[index].flags & IEEE80211_RATE_SUPPORTED);
+}
+
+static inline int
+rate_lowest_index(struct ieee80211_local *local, struct ieee80211_hw_mode *mode,
+ struct sta_info *sta)
+{
+ int i;
+
+ for (i = 0; i < mode->num_rates; i++) {
+ if (rate_supported(sta, mode, i))
+ return i;
+ }
+
+ /* warn when we cannot find a rate. */
+ WARN_ON(i == 0);
+
+ return 0;
+}
+
+static inline struct ieee80211_rate *
+rate_lowest(struct ieee80211_local *local, struct ieee80211_hw_mode *mode,
+ struct sta_info *sta)
+{
+ return &mode->rates[rate_lowest_index(local, mode, sta)];
+}
+
/* functions for rate control related to a device */
int ieee80211_init_rate_ctrl_alg(struct ieee80211_local *local,
diff --git a/net/mac80211/ieee80211_sta.c b/net/mac80211/ieee80211_sta.c
index 2a321f0..e55a9f4 100644
--- a/net/mac80211/ieee80211_sta.c
+++ b/net/mac80211/ieee80211_sta.c
@@ -2208,9 +2208,8 @@ static int ieee80211_sta_join_ibss(struct net_device *dev,
struct sk_buff *skb;
struct ieee80211_mgmt *mgmt;
struct ieee80211_tx_control control;
- struct ieee80211_rate *rate;
struct ieee80211_hw_mode *mode;
- struct rate_control_extra extra;
+ struct rate_selection ratesel;
u8 *pos;
struct ieee80211_sub_if_data *sdata;
@@ -2295,18 +2294,16 @@ static int ieee80211_sta_join_ibss(struct net_device *dev,
}
memset(&control, 0, sizeof(control));
- memset(&extra, 0, sizeof(extra));
- extra.mode = local->oper_hw_mode;
- rate = rate_control_get_rate(local, dev, skb, &extra);
- if (!rate) {
+ rate_control_get_rate(dev, local->oper_hw_mode, skb, &ratesel);
+ if (!ratesel.rate) {
printk(KERN_DEBUG "%s: Failed to determine TX rate "
"for IBSS beacon\n", dev->name);
break;
}
control.tx_rate =
((sdata->flags & IEEE80211_SDATA_SHORT_PREAMBLE) &&
- (rate->flags & IEEE80211_RATE_PREAMBLE2)) ?
- rate->val2 : rate->val;
+ (ratesel.rate->flags & IEEE80211_RATE_PREAMBLE2)) ?
+ ratesel.rate->val2 : ratesel.rate->val;
control.antenna_sel_tx = local->hw.conf.antenna_sel_tx;
control.power_level = local->hw.conf.power_level;
control.flags |= IEEE80211_TXCTL_NO_ACK;
diff --git a/net/mac80211/rc80211_simple.c b/net/mac80211/rc80211_simple.c
index da72737..c1c8b76 100644
--- a/net/mac80211/rc80211_simple.c
+++ b/net/mac80211/rc80211_simple.c
@@ -23,6 +23,8 @@
/* This is a minimal implementation of TX rate controlling that can be used
* as the default when no improved mechanisms are available. */
+#define RATE_CONTROL_NUM_DOWN 20
+#define RATE_CONTROL_NUM_UP 15
#define RATE_CONTROL_EMERG_DEC 2
#define RATE_CONTROL_INTERVAL (HZ / 20)
@@ -87,26 +89,6 @@ static void rate_control_rate_dec(struct ieee80211_local *local,
}
}
-
-static struct ieee80211_rate *
-rate_control_lowest_rate(struct ieee80211_local *local,
- struct ieee80211_hw_mode *mode)
-{
- int i;
-
- for (i = 0; i < mode->num_rates; i++) {
- struct ieee80211_rate *rate = &mode->rates[i];
-
- if (rate->flags & IEEE80211_RATE_SUPPORTED)
- return rate;
- }
-
- printk(KERN_DEBUG "rate_control_lowest_rate - no supported rates "
- "found\n");
- return &mode->rates[0];
-}
-
-
struct global_rate_control {
int dummy;
};
@@ -216,56 +198,32 @@ static void rate_control_simple_tx_status(void *priv, struct net_device *dev,
}
-static struct ieee80211_rate *
+static void
rate_control_simple_get_rate(void *priv, struct net_device *dev,
+ struct ieee80211_hw_mode *mode,
struct sk_buff *skb,
- struct rate_control_extra *extra)
+ struct rate_selection *sel)
{
struct ieee80211_local *local = wdev_priv(dev->ieee80211_ptr);
- struct ieee80211_sub_if_data *sdata;
struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) skb->data;
- struct ieee80211_hw_mode *mode = extra->mode;
struct sta_info *sta;
- int rateidx, nonerp_idx;
- u16 fc;
-
- memset(extra, 0, sizeof(*extra));
-
- fc = le16_to_cpu(hdr->frame_control);
- if ((fc & IEEE80211_FCTL_FTYPE) != IEEE80211_FTYPE_DATA ||
- (hdr->addr1[0] & 0x01)) {
- /* Send management frames and broadcast/multicast data using
- * lowest rate. */
- /* TODO: this could probably be improved.. */
- return rate_control_lowest_rate(local, mode);
- }
+ int rateidx;
sta = sta_info_get(local, hdr->addr1);
- if (!sta)
- return rate_control_lowest_rate(local, mode);
-
- sdata = IEEE80211_DEV_TO_SUB_IF(dev);
- if (sdata->bss && sdata->bss->force_unicast_rateidx > -1)
- sta->txrate = sdata->bss->force_unicast_rateidx;
+ if (!sta) {
+ sel->rate = rate_lowest(local, mode, NULL);
+ return;
+ }
rateidx = sta->txrate;
if (rateidx >= mode->num_rates)
rateidx = mode->num_rates - 1;
- sta->last_txrate = rateidx;
- nonerp_idx = rateidx;
- while (nonerp_idx > 0 &&
- ((mode->rates[nonerp_idx].flags & IEEE80211_RATE_ERP) ||
- !(mode->rates[nonerp_idx].flags & IEEE80211_RATE_SUPPORTED) ||
- !(sta->supp_rates & BIT(nonerp_idx))))
- nonerp_idx--;
- extra->nonerp = &mode->rates[nonerp_idx];
-
sta_info_put(sta);
- return &mode->rates[rateidx];
+ sel->rate = &mode->rates[rateidx];
}
diff --git a/net/mac80211/tx.c b/net/mac80211/tx.c
index 9ccf4b5..0ccc03d 100644
--- a/net/mac80211/tx.c
+++ b/net/mac80211/tx.c
@@ -567,21 +567,17 @@ ieee80211_tx_h_encrypt(struct ieee80211_txrx_data *tx)
static ieee80211_txrx_result
ieee80211_tx_h_rate_ctrl(struct ieee80211_txrx_data *tx)
{
- struct rate_control_extra extra;
+ struct rate_selection rsel;
if (likely(!tx->u.tx.rate)) {
- memset(&extra, 0, sizeof(extra));
- extra.mode = tx->u.tx.mode;
- extra.ethertype = tx->ethertype;
-
- tx->u.tx.rate = rate_control_get_rate(tx->local, tx->dev,
- tx->skb, &extra);
- if (unlikely(extra.probe != NULL)) {
+ rate_control_get_rate(tx->dev, tx->u.tx.mode, tx->skb, &rsel);
+ tx->u.tx.rate = rsel.rate;
+ if (unlikely(rsel.probe != NULL)) {
tx->u.tx.control->flags |=
IEEE80211_TXCTL_RATE_CTRL_PROBE;
tx->flags |= IEEE80211_TXRXD_TXPROBE_LAST_FRAG;
tx->u.tx.control->alt_retry_rate = tx->u.tx.rate->val;
- tx->u.tx.rate = extra.probe;
+ tx->u.tx.rate = rsel.probe;
} else
tx->u.tx.control->alt_retry_rate = -1;
@@ -592,14 +588,14 @@ ieee80211_tx_h_rate_ctrl(struct ieee80211_txrx_data *tx)
if (tx->u.tx.mode->mode == MODE_IEEE80211G &&
(tx->sdata->flags & IEEE80211_SDATA_USE_PROTECTION) &&
- (tx->flags & IEEE80211_TXRXD_FRAGMENTED) && extra.nonerp) {
+ (tx->flags & IEEE80211_TXRXD_FRAGMENTED) && rsel.nonerp) {
tx->u.tx.last_frag_rate = tx->u.tx.rate;
- if (extra.probe)
+ if (rsel.probe)
tx->flags &= ~IEEE80211_TXRXD_TXPROBE_LAST_FRAG;
else
tx->flags |= IEEE80211_TXRXD_TXPROBE_LAST_FRAG;
- tx->u.tx.rate = extra.nonerp;
- tx->u.tx.control->rate = extra.nonerp;
+ tx->u.tx.rate = rsel.nonerp;
+ tx->u.tx.control->rate = rsel.nonerp;
tx->u.tx.control->flags &= ~IEEE80211_TXCTL_RATE_CTRL_PROBE;
} else {
tx->u.tx.last_frag_rate = tx->u.tx.rate;
@@ -1665,8 +1661,7 @@ struct sk_buff *ieee80211_beacon_get(struct ieee80211_hw *hw, int if_id,
struct net_device *bdev;
struct ieee80211_sub_if_data *sdata = NULL;
struct ieee80211_if_ap *ap = NULL;
- struct ieee80211_rate *rate;
- struct rate_control_extra extra;
+ struct rate_selection rsel;
u8 *b_head, *b_tail;
int bh_len, bt_len;
@@ -1710,14 +1705,13 @@ struct sk_buff *ieee80211_beacon_get(struct ieee80211_hw *hw, int if_id,
}
if (control) {
- memset(&extra, 0, sizeof(extra));
- extra.mode = local->oper_hw_mode;
-
- rate = rate_control_get_rate(local, local->mdev, skb, &extra);
- if (!rate) {
+ rate_control_get_rate(local->mdev, local->oper_hw_mode, skb,
+ &rsel);
+ if (!rsel.rate) {
if (net_ratelimit()) {
- printk(KERN_DEBUG "%s: ieee80211_beacon_get: no rate "
- "found\n", wiphy_name(local->hw.wiphy));
+ printk(KERN_DEBUG "%s: ieee80211_beacon_get: "
+ "no rate found\n",
+ wiphy_name(local->hw.wiphy));
}
dev_kfree_skb(skb);
return NULL;
@@ -1725,8 +1719,8 @@ struct sk_buff *ieee80211_beacon_get(struct ieee80211_hw *hw, int if_id,
control->tx_rate =
((sdata->flags & IEEE80211_SDATA_SHORT_PREAMBLE) &&
- (rate->flags & IEEE80211_RATE_PREAMBLE2)) ?
- rate->val2 : rate->val;
+ (rsel.rate->flags & IEEE80211_RATE_PREAMBLE2)) ?
+ rsel.rate->val2 : rsel.rate->val;
control->antenna_sel_tx = local->hw.conf.antenna_sel_tx;
control->power_level = local->hw.conf.power_level;
control->flags |= IEEE80211_TXCTL_NO_ACK;
--
1.5.3.4
> + /* Send management frames and broadcast/multicast data using lowest
> + * rate. */
> + fc = le16_to_cpu(hdr->frame_control);
> + if ((fc & IEEE80211_FCTL_FTYPE) != IEEE80211_FTYPE_DATA ||
> + (hdr->addr1[0] & 0x01))
> + sel->rate = rate_lowest(local, mode, sta);
I'm not sure but I don't think we want this. And you should use
is_multicast_addr() or whatever it's called.
> + /* If a forced rate is in effect, select it. */
> + sdata = IEEE80211_DEV_TO_SUB_IF(dev);
> + if (sdata->bss && sdata->bss->force_unicast_rateidx > -1)
> + sel->rate = &mode->rates[sdata->bss->force_unicast_rateidx];
That's good.
> + /* If we haven't found the rate yet, ask the rate control algo. */
> + if (!sel->rate)
> + ref->ops->get_rate(ref->priv, dev, mode, skb, sel);
> + /* Select a non-ERP backup rate. */
> + if (!sel->nonerp) {
> + for (i = 0; i < mode->num_rates - 1; i++) {
> + struct ieee80211_rate *rate = &mode->rates[i];
> + if (sel->rate->rate < rate->rate)
> + break;
> +
> + if (rate_supported(sta, mode, i) &&
> + !(rate->flags & IEEE80211_RATE_ERP))
> + sel->nonerp = rate;
> + }
> + }
That I'm not sure about. This is the fallback rate?
johannes
On Sat, 2007-12-08 at 12:36 +0100, Johannes Berg wrote:
> On Sat, 2007-12-08 at 12:33 +0100, Mattias Nissler wrote:
> > On Sat, 2007-12-08 at 12:29 +0100, Johannes Berg wrote:
> > > > + /* Send management frames and broadcast/multicast data using lowest
> > > > + * rate. */
> > > > + fc = le16_to_cpu(hdr->frame_control);
> > > > + if ((fc & IEEE80211_FCTL_FTYPE) != IEEE80211_FTYPE_DATA ||
> > > > + (hdr->addr1[0] & 0x01))
> > > > + sel->rate = rate_lowest(local, mode, sta);
> > >
> > > I'm not sure but I don't think we want this. And you should use
> > > is_multicast_addr() or whatever it's called.
> >
> > This piece comes directly from the old "simple" algo. You're right about
> > is_multicast_addr. I agree this is something we might to get rid of, but
> > I leave that decision to you.
>
> Right, but I guess that Intel's algorithms do something different and
> this would break it. IMHO that decision should stay in the algorithm
> itself.
Actually, I carefully check the iwlwifi code and it copies this exact
code. Finding it in there as well actually convinced me to move it out
of the rate control.
>
> > Yes. It's after the get_rate() call so the algorithm can override it.
> > But if it doesn't we compute it ourselves.
>
> Hmm. Then the algorithm can't specify "no fallback rate", can it?
Correct. But why would you want that to be possible?
Mattias
On Sat, 2007-12-08 at 12:33 +0100, Mattias Nissler wrote:
> >
> > > + /* If we haven't found the rate yet, ask the rate control algo. */
> > > + if (!sel->rate)
> > > + ref->ops->get_rate(ref->priv, dev, mode, skb, sel);
> >
> > > + /* Select a non-ERP backup rate. */
> > > + if (!sel->nonerp) {
> > > + for (i = 0; i < mode->num_rates - 1; i++) {
> > > + struct ieee80211_rate *rate = &mode->rates[i];
> > > + if (sel->rate->rate < rate->rate)
> > > + break;
> > > +
> > > + if (rate_supported(sta, mode, i) &&
> > > + !(rate->flags & IEEE80211_RATE_ERP))
> > > + sel->nonerp = rate;
> > > + }
> > > + }
> >
> > That I'm not sure about. This is the fallback rate?
>
> Yes. It's after the get_rate() call so the algorithm can override it.
> But if it doesn't we compute it ourselves.
To be a little more specific, it's the non-extended-rate-set rate. So
the code falls back to this one e.g. if it's an AP has 80211.g but
stations that are only 80211.b
Mattias
> > Right, but I guess that Intel's algorithms do something different and
> > this would break it. IMHO that decision should stay in the algorithm
> > itself.
>
> Actually, I carefully check the iwlwifi code and it copies this exact
> code. Finding it in there as well actually convinced me to move it out
> of the rate control.
Heh, ok. Let's leave it like this then.
> > > Yes. It's after the get_rate() call so the algorithm can override it.
> > > But if it doesn't we compute it ourselves.
> >
> > Hmm. Then the algorithm can't specify "no fallback rate", can it?
>
> Correct. But why would you want that to be possible?
No idea :)
johannes
On Sat, 2007-12-08 at 12:33 +0100, Mattias Nissler wrote:
> On Sat, 2007-12-08 at 12:29 +0100, Johannes Berg wrote:
> > > + /* Send management frames and broadcast/multicast data using lowest
> > > + * rate. */
> > > + fc = le16_to_cpu(hdr->frame_control);
> > > + if ((fc & IEEE80211_FCTL_FTYPE) != IEEE80211_FTYPE_DATA ||
> > > + (hdr->addr1[0] & 0x01))
> > > + sel->rate = rate_lowest(local, mode, sta);
> >
> > I'm not sure but I don't think we want this. And you should use
> > is_multicast_addr() or whatever it's called.
>
> This piece comes directly from the old "simple" algo. You're right about
> is_multicast_addr. I agree this is something we might to get rid of, but
> I leave that decision to you.
Right, but I guess that Intel's algorithms do something different and
this would break it. IMHO that decision should stay in the algorithm
itself.
> Yes. It's after the get_rate() call so the algorithm can override it.
> But if it doesn't we compute it ourselves.
Hmm. Then the algorithm can't specify "no fallback rate", can it? Well,
this will have to be reviewed anyway when the API is changed to support
minstrel.
johannes
On Sat, 2007-12-08 at 12:29 +0100, Johannes Berg wrote:
> > + /* Send management frames and broadcast/multicast data using lowest
> > + * rate. */
> > + fc = le16_to_cpu(hdr->frame_control);
> > + if ((fc & IEEE80211_FCTL_FTYPE) != IEEE80211_FTYPE_DATA ||
> > + (hdr->addr1[0] & 0x01))
> > + sel->rate = rate_lowest(local, mode, sta);
>
> I'm not sure but I don't think we want this. And you should use
> is_multicast_addr() or whatever it's called.
This piece comes directly from the old "simple" algo. You're right about
is_multicast_addr. I agree this is something we might to get rid of, but
I leave that decision to you.
>
> > + /* If a forced rate is in effect, select it. */
> > + sdata = IEEE80211_DEV_TO_SUB_IF(dev);
> > + if (sdata->bss && sdata->bss->force_unicast_rateidx > -1)
> > + sel->rate = &mode->rates[sdata->bss->force_unicast_rateidx];
>
> That's good.
>
> > + /* If we haven't found the rate yet, ask the rate control algo. */
> > + if (!sel->rate)
> > + ref->ops->get_rate(ref->priv, dev, mode, skb, sel);
>
> > + /* Select a non-ERP backup rate. */
> > + if (!sel->nonerp) {
> > + for (i = 0; i < mode->num_rates - 1; i++) {
> > + struct ieee80211_rate *rate = &mode->rates[i];
> > + if (sel->rate->rate < rate->rate)
> > + break;
> > +
> > + if (rate_supported(sta, mode, i) &&
> > + !(rate->flags & IEEE80211_RATE_ERP))
> > + sel->nonerp = rate;
> > + }
> > + }
>
> That I'm not sure about. This is the fallback rate?
Yes. It's after the get_rate() call so the algorithm can override it.
But if it doesn't we compute it ourselves.
Mattias