neels has uploaded this change for review. (
https://gerrit.osmocom.org/c/osmo-bsc/+/21978 )
Change subject: hodec2: cosmetic: clarify afs_bias, simplify
pick_better_lchan_to_move()
......................................................................
hodec2: cosmetic: clarify afs_bias, simplify pick_better_lchan_to_move()
Instead of passing the TCH/H -> TCH/F bias (AFS bias) in local
variables, rather store it in the ho_candidate struct next to the other
rxlev related values.
Add the AFS bias to the compared rxlev in pick_better_lchan_to_move().
Modify pick_better_lchan_to_move() to simpler semantics of returning
either a or b.
No functional change.
Change-Id: I73860abdf2a77270ca4851ad58c09767d1bb08f1
---
M src/osmo-bsc/handover_decision_2.c
1 file changed, 36 insertions(+), 50 deletions(-)
git pull ssh://gerrit.osmocom.org:29418/osmo-bsc refs/changes/78/21978/1
diff --git a/src/osmo-bsc/handover_decision_2.c
b/src/osmo-bsc/handover_decision_2.c
index ae9435f..eb72e11 100644
--- a/src/osmo-bsc/handover_decision_2.c
+++ b/src/osmo-bsc/handover_decision_2.c
@@ -106,6 +106,7 @@
uint8_t requirements; /* what is fulfilled */
int rxlev_current;
int rxlev_target;
+ int rxlev_afs_bias;
};
enum ho_reason {
@@ -1398,63 +1399,55 @@
/* Given two candidates, pick the one that should rather be moved during
handover.
* Return the better candidate in out-parameters best_cand and best_avg_db.
*/
-static bool pick_better_lchan_to_move(bool want_highest_db,
- struct ho_candidate **best_cand_p,
unsigned int *best_avg_db_p,
- struct ho_candidate *other_cand, unsigned
int other_avg_db)
+static struct ho_candidate *pick_better_lchan_to_move(bool want_highest_db,
+ struct ho_candidate *a,
+ struct ho_candidate *b)
{
- if (!*best_cand_p)
- goto return_other;
+ int a_rxlev;
+ int b_rxlev;
- if (want_highest_db && (*best_avg_db_p < other_avg_db))
- goto return_other;
- if (!want_highest_db && (*best_avg_db_p > other_avg_db))
- goto return_other;
+ if (!a)
+ return b;
+ if (!b)
+ return a;
+
+ a_rxlev = a->rxlev_target + a->rxlev_afs_bias;
+ b_rxlev = b->rxlev_target + b->rxlev_afs_bias;
+
+ if (want_highest_db && a_rxlev < b_rxlev)
+ return b;
+ if (!want_highest_db && a_rxlev > b_rxlev)
+ return b;
/* The two lchans have identical ratings, prefer picking a dynamic
timeslot: free PDCH and allow more timeslot
* type flexibility for further congestion resolution. */
- if (lchan_is_on_dynamic_ts(other_cand->lchan)) {
+ if (lchan_is_on_dynamic_ts(b->lchan)) {
/* If both are dynamic, prefer one that completely (or to a
higher degree) frees its timeslot. */
- if (lchan_is_on_dynamic_ts((*best_cand_p)->lchan)
- && ts_usage_count((*best_cand_p)->lchan->ts) <
ts_usage_count(other_cand->lchan->ts))
- return false;
+ if (lchan_is_on_dynamic_ts(a->lchan)
+ && ts_usage_count(a->lchan->ts) <
ts_usage_count(b->lchan->ts))
+ return a;
/* If both equally satisfy these preferences, it does not
matter which one is picked.
* Give slight preference to moving later dyn TS, so that a
free dyn TS may group with following static
* PDCH, though this depends on how the user configured the TS
-- not harmful to do so anyway. */
- goto return_other;
+ return b;
}
- /* keep the same candidate. */
- return false;
-
-return_other:
- *best_cand_p = other_cand;
- *best_avg_db_p = other_avg_db;
- return true;
+ return a;
}
-static struct ho_candidate *pick_best_candidate(int *applied_afs_bias,
- struct ho_candidate *clist, int
clist_len,
+static struct ho_candidate *pick_best_candidate(struct ho_candidate *clist,
int clist_len,
bool want_highest_db,
bool
omit_intra_cell_upgrade_to_tchf,
bool
only_intra_cell_upgrade_to_tchf,
uint8_t for_requirement)
{
struct ho_candidate *result = NULL;
- unsigned int result_avg_rxlev;
- int result_afs_bias = 0;
int i;
- if (applied_afs_bias)
- *applied_afs_bias = 0;
-
- result_avg_rxlev = want_highest_db ? 0 : INT_MAX;
-
for (i = 0; i < clist_len; i++) {
struct ho_candidate *c = &clist[i];
bool intra_cell;
bool upgrade_to_tch_f;
- int avg_rxlev;
- int afs_bias;
/* For multiple passes of congestion resolution, already
handovered candidates are marked by lchan =
* NULL. (though at the time of writing, multiple passes of
congestion resolution are DISABLED.) */
@@ -1478,21 +1471,15 @@
&& (intra_cell && upgrade_to_tch_f))
continue;
- avg_rxlev = c->rxlev_target;
-
/* improve AHS */
if (upgrade_to_tch_f)
- afs_bias = ho_get_hodec2_afs_bias_rxlev(c->bts->ho);
+ c->rxlev_afs_bias =
ho_get_hodec2_afs_bias_rxlev(c->bts->ho);
else
- afs_bias = 0;
- avg_rxlev += afs_bias;
+ c->rxlev_afs_bias = 0;
- if (pick_better_lchan_to_move(want_highest_db, &result,
&result_avg_rxlev, c, avg_rxlev))
- result_afs_bias = afs_bias;
+ result = pick_better_lchan_to_move(want_highest_db, result, c);
}
- if (applied_afs_bias)
- *applied_afs_bias = result_afs_bias;
return result;
}
@@ -1556,7 +1543,6 @@
struct ho_candidate *best_cand = NULL;
int rc = 0;
int any_ho = 0;
- int is_improved = 0;
if (tchf_congestion < 0)
tchf_congestion = 0;
@@ -1657,7 +1643,7 @@
/* TODO: attempt inter-BSC HO if no local cells qualify, and rely on
the remote BSS to
* deny receiving the handover if it also considers itself congested.
Maybe do that only
* when the cell is absolutely full, i.e. not only min-free-slots. (x)
*/
- best_cand = pick_best_candidate(&is_improved, clist, candidates,
+ best_cand = pick_best_candidate(clist, candidates,
/* want_highest_db */ true,
/* omit_intra_cell_upgrade_to_tchf */
true,
/* only_intra_cell_upgrade_to_tchf */
false,
@@ -1666,7 +1652,7 @@
any_ho = 1;
LOGPHOCAND(best_cand, LOGL_DEBUG, "Best candidate: RX level
%d%s\n",
rxlev2dbm(best_cand->rxlev_target),
- is_improved ? " (applied AHS->AFS bias)" : "");
+ best_cand->rxlev_afs_bias ? " (applied AHS->AFS
bias)" : "");
trigger_ho(best_cand, best_cand->requirements &
REQUIREMENT_B_MASK);
#if 0
/* if there is still congestion, mark lchan as deleted
@@ -1698,7 +1684,7 @@
* but simply pick the lowest one.
* Upgrading TCH/H channels obviously only applies when TCH/H is
actually congested. */
if (tchh_congestion > 0)
- best_cand = pick_best_candidate(&is_improved, clist, candidates,
+ best_cand = pick_best_candidate(clist, candidates,
/* want_highest_db */ false,
/*
omit_intra_cell_upgrade_to_tchf */ false,
/*
only_intra_cell_upgrade_to_tchf */ true,
@@ -1707,7 +1693,7 @@
any_ho = 1;
LOGPHOCAND(best_cand, LOGL_INFO, "Worst candidate: RX level %d
from TCH/H -> TCH/F%s\n",
rxlev2dbm(best_cand->rxlev_target),
- is_improved ? " (applied AHS -> AFS rxlev bias)" :
"");
+ best_cand->rxlev_afs_bias ? " (applied AHS -> AFS
rxlev bias)" : "");
trigger_ho(best_cand, best_cand->requirements &
REQUIREMENT_B_MASK);
#if 0
/* if there is still congestion, mark lchan as deleted
@@ -1733,7 +1719,7 @@
/* Select best candidate that balances congestion.
* Again no remote BSS.
* Again no TCH/H -> F upgrades within the same cell. */
- best_cand = pick_best_candidate(&is_improved, clist, candidates,
+ best_cand = pick_best_candidate(clist, candidates,
/* want_highest_db */ true,
/* omit_intra_cell_upgrade_to_tchf */
true,
/* only_intra_cell_upgrade_to_tchf */
false,
@@ -1742,7 +1728,7 @@
any_ho = 1;
LOGPHOCAND(best_cand, LOGL_INFO, "Best candidate: RX level
%d%s\n",
rxlev2dbm(best_cand->rxlev_target),
- is_improved ? " (applied AHS -> AFS rxlev bias)" :
"");
+ best_cand->rxlev_afs_bias ? " (applied AHS -> AFS
rxlev bias)" : "");
trigger_ho(best_cand, best_cand->requirements &
REQUIREMENT_C_MASK);
#if 0
/* if there is still congestion, mark lchan as deleted
@@ -1774,7 +1760,7 @@
/* Look for upgrading TCH/H to TCH/F within the same cell, which
balances congestion, again upgrade the TCH/H
* lchan that has the worst reception: */
if (tchh_congestion > 0)
- best_cand = pick_best_candidate(&is_improved, clist, candidates,
+ best_cand = pick_best_candidate(clist, candidates,
/* want_highest_db */ false,
/*
omit_intra_cell_upgrade_to_tchf */ false,
/*
only_intra_cell_upgrade_to_tchf */ true,
@@ -1785,7 +1771,7 @@
any_ho = 1;
LOGPHOCAND(best_cand, LOGL_INFO, "Worst candidate: RX level %d
from TCH/H -> TCH/F%s\n",
rxlev2dbm(best_cand->rxlev_target),
- is_improved ? " (applied AHS -> AFS rxlev bias)" :
"");
+ best_cand->rxlev_afs_bias ? " (applied AHS -> AFS
rxlev bias)" : "");
trigger_ho(best_cand, best_cand->requirements &
REQUIREMENT_C_MASK);
#if 0
/* if there is still congestion, mark lchan as deleted
--
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Gerrit-Project: osmo-bsc
Gerrit-Branch: master
Gerrit-Change-Id: I73860abdf2a77270ca4851ad58c09767d1bb08f1
Gerrit-Change-Number: 21978
Gerrit-PatchSet: 1
Gerrit-Owner: neels <[email protected]>
Gerrit-MessageType: newchange
