Simplify TS alloc: split USF/UL allocation

* move USF allocation into separate function
* document USF allocation

This allows to clearly see where selected UL TS is forced into single TS
in algorithm B allocator.

Change-Id: I563dc10827ce68295553f88f3bf2e1fc0ba595c1
Related: OS#2282
This commit is contained in:
Max 2018-01-31 17:21:21 +01:00 committed by Harald Welte
parent 0cc7212cfd
commit 2afec6dba5
1 changed files with 42 additions and 19 deletions

View File

@ -790,6 +790,44 @@ static int tbf_select_slot_set(const gprs_rlcmac_tbf *tbf, const gprs_rlcmac_trx
return sl;
}
/*! Allocate USF according to a given UL TS mapping
*
* N. B: this is legacy implementation which ignores given selected_ul_slots
* \param[in] trx Pointer to TRX object
* \param[in] tbf Pointer to TBF object
* \param[in] first_common_ts First TS which is common to both UL and DL
* \param[in] selected_ul_slots set of UL timeslots selected for allocation
* \param[in] dl_slots set of DL timeslots
* \param[out] usf array for allocated USF
* \returns updated UL TS or negative on error
*/
static int allocate_usf(const gprs_rlcmac_trx *trx, int8_t first_common_ts, uint8_t selected_ul_slots, uint8_t dl_slots,
int *usf)
{
int free_usf = -1, ts;
uint8_t ul_slots = selected_ul_slots;
if (first_common_ts >= 0)
ul_slots = 1 << first_common_ts;
else
ul_slots = ul_slots & dl_slots;
ts = find_least_busy_pdch(trx, GPRS_RLCMAC_UL_TBF, ul_slots, compute_usage_by_num_tbfs, NULL, &free_usf);
if (free_usf < 0 || ts < 0) {
LOGP(DRLCMAC, LOGL_NOTICE, "No USF available\n");
return -EBUSY;
}
OSMO_ASSERT(ts >= 0 && ts <= 8);
/* We will stick to that single UL slot, unreserve the others */
ul_slots = 1 << ts;
usf[ts] = free_usf;
return ul_slots;
}
/*! Slot Allocation: Algorithm B
*
* Assign as many downlink slots as possible.
@ -867,27 +905,12 @@ int alloc_algorithm_b(struct gprs_rlcmac_bts *bts, GprsMs *ms_, struct gprs_rlcm
dl_slots = rc;
update_slot_counters(dl_slots, reserved_dl_slots, &slotcount, &avail_count);
} else {
int free_usf = -1;
ul_slots = rc;
if (first_common_ts >= 0)
ul_slots = 1 << first_common_ts;
else
ul_slots = ul_slots & dl_slots;
ts = find_least_busy_pdch(trx, GPRS_RLCMAC_UL_TBF, ul_slots, compute_usage_by_num_tbfs, NULL, &free_usf);
if (free_usf < 0) {
LOGP(DRLCMAC, LOGL_NOTICE, "No USF available\n");
return -EBUSY;
}
OSMO_ASSERT(ts >= 0 && ts <= 8);
rc = allocate_usf(trx, first_common_ts, rc, dl_slots, usf);
if (rc < 0)
return rc;
/* We will stick to that single UL slot, unreserve the others */
ul_slots = 1 << ts;
usf[ts] = free_usf;
ul_slots = rc;
reserved_ul_slots = ul_slots;
update_slot_counters(ul_slots, reserved_ul_slots, &slotcount, &avail_count);