alloc_algo_b: Select TRX with least assigned TFIs during TBF alloc
Before this patch, it would always allocate all TBFs on the first TRX
until all TFIs were filled, then second, and so on. But it would
actually fail around 8th MS requesting an UL TBF because despite a TFI
was successfuly assigned, because all USFs were already exhausted for
that PDCH.
Related: OS#1775
Change-Id: Iccfc8acfbfdc258ed16cc5af01f12b376fe73b72
diff --git a/src/bts.cpp b/src/bts.cpp
index da62b30..be957fa 100644
--- a/src/bts.cpp
+++ b/src/bts.cpp
@@ -536,18 +536,51 @@
return m_bts.trx[trx].pdch[ts].ul_tbf_by_tfi(tfi);
}
+static unsigned int trx_count_free_tfi(const struct gprs_rlcmac_trx *trx, enum gprs_rlcmac_tbf_direction dir, uint8_t *first_free_tfi)
+{
+ const struct gprs_rlcmac_pdch *pdch;
+ uint8_t ts;
+ unsigned int i;
+ unsigned int free_tfi_cnt = 0;
+ bool has_pdch = false;
+ uint32_t mask = NO_FREE_TFI;
+
+ for (ts = 0; ts < ARRAY_SIZE(trx->pdch); ts++) {
+ pdch = &trx->pdch[ts];
+ if (!pdch->is_enabled())
+ continue;
+ has_pdch = true;
+ mask &= ~pdch->assigned_tfi(dir);
+ }
+
+ if (!has_pdch || !mask) {
+ *first_free_tfi = (uint8_t)-1;
+ return 0;
+ }
+
+ /* Count free tfis and return */
+ for (i = 0; i < sizeof(mask) * 8 ; i++) {
+ if (mask & 1) {
+ if (free_tfi_cnt == 0)
+ *first_free_tfi = i;
+ free_tfi_cnt++;
+ }
+ mask >>= 1;
+ }
+ return free_tfi_cnt;
+}
+
/*
- * Search for free TFI and return TFI, TRX.
- * This method returns the first TFI that is currently not used in any PDCH of
- * a TRX. The first TRX that contains such an TFI is returned. Negative values
- * indicate errors.
+ * Search for free TFI and return TFI, TRX. This method returns the first TFI
+ * that is currently not used in any PDCH of a the TRX with least TFIs currently
+ * assigned. Negative values indicate errors.
*/
int BTS::tfi_find_free(enum gprs_rlcmac_tbf_direction dir, uint8_t *_trx, int8_t use_trx) const
{
- const struct gprs_rlcmac_pdch *pdch;
- uint32_t free_tfis;
- bool has_pdch = false;
- uint8_t trx_from, trx_to, trx, ts, tfi;
+ uint8_t trx_from, trx_to, trx;
+ uint8_t best_trx_nr = 0xff;
+ unsigned int best_cnt = 0;
+ uint8_t best_first_tfi = 0;
if (use_trx >= 0 && use_trx < 8)
trx_from = trx_to = use_trx;
@@ -558,48 +591,27 @@
/* find a TFI that is unused on all PDCH */
for (trx = trx_from; trx <= trx_to; trx++) {
- bool trx_has_pdch = false;
-
- free_tfis = NO_FREE_TFI;
-
- for (ts = 0; ts < 8; ts++) {
- pdch = &m_bts.trx[trx].pdch[ts];
- if (!pdch->is_enabled())
- continue;
- free_tfis &= ~pdch->assigned_tfi(dir);
- trx_has_pdch = true;
- has_pdch = true;
+ uint8_t tmp_first_tfi;
+ unsigned int tmp_cnt;
+ tmp_cnt = trx_count_free_tfi(&m_bts.trx[trx], dir, &tmp_first_tfi);
+ if (tmp_cnt > best_cnt) {
+ best_cnt = tmp_cnt;
+ best_first_tfi = tmp_first_tfi;
+ best_trx_nr = trx;
}
- if (trx_has_pdch && free_tfis)
- break;
-
- free_tfis = 0;
- }
- if (!has_pdch) {
- LOGP(DRLCMAC, LOGL_NOTICE, "No PDCH available.\n");
- return -EINVAL;
}
- if (!free_tfis) {
+ if (best_trx_nr == 0xff || best_cnt == 0) {
LOGP(DRLCMAC, LOGL_NOTICE, "No TFI available (suggested TRX: %d).\n", use_trx);
return -EBUSY;
}
+ OSMO_ASSERT(best_first_tfi < 32);
- LOGP(DRLCMAC, LOGL_DEBUG,
- "Searching for first unallocated TFI: TRX=%d\n", trx);
-
- /* find the first */
- for (tfi = 0; tfi < 32; tfi++) {
- if (free_tfis & 1 << tfi)
- break;
- }
-
- OSMO_ASSERT(tfi < 32);
-
- LOGP(DRLCMAC, LOGL_DEBUG, " Found TFI=%d.\n", tfi);
- *_trx = trx;
- return tfi;
+ LOGP(DRLCMAC, LOGL_DEBUG, "Found first unallocated TRX=%d TFI=%d\n",
+ best_trx_nr, best_first_tfi);
+ *_trx = best_trx_nr;
+ return best_first_tfi;
}
int BTS::rcv_imm_ass_cnf(const uint8_t *data, uint32_t fn)