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osmo-pcu/src/gprs_rlcmac_ts_alloc.cpp

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/* gprs_rlcmac.cpp
*
* Copyright (C) 2012 Ivan Klyuchnikov
* Copyright (C) 2012 Andreas Eversberg <jolly@eversberg.eu>
* Copyright (C) 2013 by Holger Hans Peter Freyther
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version 2
* of the License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
*/
#include <gprs_rlcmac.h>
#include <gprs_debug.h>
#include <bts.h>
#include <tbf.h>
#include <pdch.h>
#include <gprs_ms.h>
#include <pcu_utils.h>
#include <errno.h>
#include <values.h>
extern "C" {
#include "mslot_class.h"
#include <osmocom/core/linuxlist.h>
#include <osmocom/core/logging.h>
#include <osmocom/core/utils.h>
}
/* Consider a PDCH as idle if has at most this number of TBFs assigned to it */
#define PDCH_IDLE_TBF_THRESH 1
static char *set_flag_chars(char *buf, uint8_t val, char set_char, char unset_char = 0)
{
int i;
for (i = 0; i < 8; i += 1, val = val >> 1) {
if (val & 1)
buf[i] = set_char;
else if (unset_char)
buf[i] = unset_char;
}
return buf;
}
static bool test_and_set_bit(uint32_t *bits, size_t elem)
{
bool was_set = bits[elem/32] & (1 << (elem % 32));
bits[elem/32] |= (1 << (elem % 32));
return was_set;
}
static int find_possible_pdchs(const struct gprs_rlcmac_trx *trx, size_t max_slots, uint8_t mask,
const char *mask_reason = NULL)
{
unsigned ts;
int valid_ts_set = 0;
int8_t last_tsc = -1; /* must be signed */
for (ts = 0; ts < ARRAY_SIZE(trx->pdch); ts++) {
const struct gprs_rlcmac_pdch *pdch;
pdch = &trx->pdch[ts];
if (!pdch->is_enabled()) {
LOGP(DRLCMAC, LOGL_DEBUG, "- Skipping TS %d, because "
"not enabled\n", ts);
continue;
}
if (((1 << ts) & mask) == 0) {
if (mask_reason)
LOGP(DRLCMAC, LOGL_DEBUG,
"- Skipping TS %d, because %s\n",
ts, mask_reason);
continue;
}
if (max_slots > 1) {
/* check if TSC changes, see TS 45.002, 6.4.2 */
if (last_tsc < 0)
last_tsc = pdch->tsc;
else if (last_tsc != pdch->tsc) {
LOGP(DRLCMAC, LOGL_ERROR,
"Skipping TS %d of TRX=%d, because it "
"has different TSC than lower TS of TRX. "
"In order to allow multislot, all "
"slots must be configured with the same "
"TSC!\n", ts, trx->trx_no);
continue;
}
}
valid_ts_set |= 1 << ts;
}
return valid_ts_set;
}
static int compute_usage_by_num_tbfs(const struct gprs_rlcmac_pdch *pdch, enum gprs_rlcmac_tbf_direction dir)
{
return pdch->num_tbfs(dir);
}
static int compute_usage_by_reservation(const struct gprs_rlcmac_pdch *pdch, enum gprs_rlcmac_tbf_direction)
{
return
pdch->num_reserved(GPRS_RLCMAC_DL_TBF) +
pdch->num_reserved(GPRS_RLCMAC_UL_TBF);
}
static int compute_usage_for_algo_a(const struct gprs_rlcmac_pdch *pdch, enum gprs_rlcmac_tbf_direction dir)
{
int usage =
pdch->num_tbfs(GPRS_RLCMAC_DL_TBF) +
pdch->num_tbfs(GPRS_RLCMAC_UL_TBF) +
compute_usage_by_reservation(pdch, dir);
if (pdch->assigned_tfi(reverse(dir)) == NO_FREE_TFI)
/* No TFI in the opposite direction, avoid it */
usage += 32;
return usage;
}
/*! Return the TS which corresponds to least busy PDCH
*
* \param[in] trx Pointer to TRX object
* \param[in] dir TBF direction
* \param[in] mask set of available timeslots
* \param[in] fn Function pointer to function which computes number of associated TBFs
* \param[out] free_tfi Free TFI
* \param[out] free_usf Free USF
* \returns TS number or -1 if unable to find
*/
static int find_least_busy_pdch(const struct gprs_rlcmac_trx *trx, enum gprs_rlcmac_tbf_direction dir, uint8_t mask,
int (*fn)(const struct gprs_rlcmac_pdch *, enum gprs_rlcmac_tbf_direction dir),
int *free_tfi = 0, int *free_usf = 0)
{
unsigned ts;
int min_used = INT_MAX;
int min_ts = -1;
int min_tfi = -1;
int min_usf = -1;
for (ts = 0; ts < ARRAY_SIZE(trx->pdch); ts++) {
const struct gprs_rlcmac_pdch *pdch = &trx->pdch[ts];
int num_tbfs;
int usf = -1; /* must be signed */
int tfi = -1;
if (((1 << ts) & mask) == 0)
continue;
num_tbfs = fn(pdch, dir);
if (num_tbfs < min_used) {
/* We have found a candidate */
/* Make sure that a TFI is available */
if (free_tfi) {
tfi = find_free_tfi(pdch->assigned_tfi(dir));
if (tfi < 0) {
LOGP(DRLCMAC, LOGL_DEBUG,
"- Skipping TS %d, because "
"no TFI available\n", ts);
continue;
}
}
/* Make sure that an USF is available */
if (dir == GPRS_RLCMAC_UL_TBF) {
usf = find_free_usf(pdch->assigned_usf());
if (usf < 0) {
LOGP(DRLCMAC, LOGL_DEBUG,
"- Skipping TS %d, because "
"no USF available\n", ts);
continue;
}
}
if (min_ts >= 0)
LOGP(DRLCMAC, LOGL_DEBUG,
"- Skipping TS %d, because "
"num TBFs %d > %d\n",
min_ts, min_used, num_tbfs);
min_used = num_tbfs;
min_ts = ts;
min_tfi = tfi;
min_usf = usf;
} else {
LOGP(DRLCMAC, LOGL_DEBUG,
"- Skipping TS %d, because "
"num TBFs %d >= %d\n",
ts, num_tbfs, min_used);
}
}
if (min_ts < 0)
return -1;
if (free_tfi)
*free_tfi = min_tfi;
if (free_usf)
*free_usf = min_usf;
return min_ts;
}
static void attach_tbf_to_pdch(struct gprs_rlcmac_pdch *pdch,
struct gprs_rlcmac_tbf *tbf)
{
if (tbf->pdch[pdch->ts_no])
tbf->pdch[pdch->ts_no]->detach_tbf(tbf);
tbf->pdch[pdch->ts_no] = pdch;
pdch->attach_tbf(tbf);
}
static void assign_uplink_tbf_usf(struct gprs_rlcmac_pdch *pdch, struct gprs_rlcmac_ul_tbf *tbf, uint8_t tfi, int8_t usf)
{
tbf->m_tfi = tfi;
tbf->m_usf[pdch->ts_no] = usf;
attach_tbf_to_pdch(pdch, tbf);
}
static void assign_dlink_tbf(struct gprs_rlcmac_pdch *pdch, struct gprs_rlcmac_dl_tbf *tbf, uint8_t tfi)
{
tbf->m_tfi = tfi;
attach_tbf_to_pdch(pdch, tbf);
}
static int find_trx(const struct gprs_rlcmac_bts *bts_data, const GprsMs *ms, int8_t use_trx)
{
unsigned trx_no;
unsigned ts;
/* We must use the TRX currently actively used by an MS */
if (ms && ms->current_trx())
return ms->current_trx()->trx_no;
if (use_trx >= 0 && use_trx < 8)
return use_trx;
/* Find the first TRX that has a PDCH with a free UL and DL TFI */
for (trx_no = 0; trx_no < ARRAY_SIZE(bts_data->trx); trx_no += 1) {
const struct gprs_rlcmac_trx *trx = &bts_data->trx[trx_no];
for (ts = 0; ts < ARRAY_SIZE(trx->pdch); ts++) {
const struct gprs_rlcmac_pdch *pdch = &trx->pdch[ts];
if (!pdch->is_enabled())
continue;
if (pdch->assigned_tfi(GPRS_RLCMAC_UL_TBF) == NO_FREE_TFI)
continue;
if (pdch->assigned_tfi(GPRS_RLCMAC_DL_TBF) == NO_FREE_TFI)
continue;
return trx_no;
}
}
return -EBUSY;
}
static bool idle_pdch_avail(const struct gprs_rlcmac_bts *bts_data)
{
unsigned trx_no;
unsigned ts;
/* Find the first PDCH with an unused DL TS */
for (trx_no = 0; trx_no < ARRAY_SIZE(bts_data->trx); trx_no += 1) {
const struct gprs_rlcmac_trx *trx = &bts_data->trx[trx_no];
for (ts = 0; ts < ARRAY_SIZE(trx->pdch); ts++) {
const struct gprs_rlcmac_pdch *pdch = &trx->pdch[ts];
if (!pdch->is_enabled())
continue;
if (pdch->num_tbfs(GPRS_RLCMAC_DL_TBF) > PDCH_IDLE_TBF_THRESH)
continue;
return true;
}
}
return false;
}
/*! Return free TFI
*
* \param[in] bts Pointer to BTS struct
* \param[in] trx Optional pointer to TRX struct
* \param[in] ms Pointer to MS object
* \param[in] dir DL or UL direction
* \param[in] use_trx which TRX to use or -1 if it should be selected based on what MS uses
* \param[out] trx_no_ TRX number on which TFI was found
* \returns negative error code or 0 on success
*/
static int tfi_find_free(const BTS *bts, const gprs_rlcmac_trx *trx, const GprsMs *ms,
enum gprs_rlcmac_tbf_direction dir, int8_t use_trx, uint8_t *trx_no_)
{
int tfi;
uint8_t trx_no;
if (trx) {
if (use_trx >= 0 && use_trx != trx->trx_no) {
LOGP(DRLCMAC, LOGL_ERROR, "- Requested incompatible TRX %d (current is %d)\n",
use_trx, trx->trx_no);
return -EINVAL;
}
use_trx = trx->trx_no;
}
if (use_trx == -1 && ms->current_trx())
use_trx = ms->current_trx()->trx_no;
tfi = bts->tfi_find_free(dir, &trx_no, use_trx);
if (tfi < 0)
return -EBUSY;
if (trx_no_)
*trx_no_ = trx_no;
return tfi;
}
/*! Slot Allocation: Algorithm A
*
* Assign single slot for uplink and downlink
*
* \param[in,out] bts Pointer to BTS struct
* \param[in,out] ms_ Pointer to MS object
* \param[in,out] tbf_ Pointer to TBF struct
* \param[in] single flag indicating if we should force single-slot allocation
* \param[in] use_trx which TRX to use or -1 if it should be selected during allocation
* \returns negative error code or 0 on success
*/
int alloc_algorithm_a(struct gprs_rlcmac_bts *bts, GprsMs *ms_, struct gprs_rlcmac_tbf *tbf_, bool single,
int8_t use_trx)
{
struct gprs_rlcmac_pdch *pdch;
int ts = -1;
uint8_t ul_slots, dl_slots;
int trx_no;
int tfi = -1;
int usf = -1;
int mask = 0xff;
const char *mask_reason = NULL;
const GprsMs *ms = ms_;
const gprs_rlcmac_tbf *tbf = tbf_;
gprs_rlcmac_trx *trx = ms->current_trx();
LOGP(DRLCMAC, LOGL_DEBUG, "Slot Allocation (Algorithm A) for class "
"%d\n", tbf->ms_class());
trx_no = find_trx(bts, ms, use_trx);
if (trx_no < 0) {
LOGP(DRLCMAC, LOGL_NOTICE,
"- Failed to find a usable TRX (TFI exhausted)\n");
return trx_no;
}
if (!trx)
trx = &bts->trx[trx_no];
dl_slots = ms->reserved_dl_slots();
ul_slots = ms->reserved_ul_slots();
ts = ms->first_common_ts();
if (ts >= 0) {
mask_reason = "need to reuse TS";
mask = 1 << ts;
} else if (dl_slots || ul_slots) {
mask_reason = "need to use a reserved common TS";
mask = dl_slots & ul_slots;
}
mask = find_possible_pdchs(trx, 1, mask, mask_reason);
if (!mask)
return -EINVAL;
ts = find_least_busy_pdch(trx, tbf->direction, mask,
compute_usage_for_algo_a,
&tfi, &usf);
if (tbf->direction == GPRS_RLCMAC_UL_TBF && usf < 0) {
LOGP(DRLCMAC, LOGL_NOTICE, "- Failed "
"to allocate a TS, no USF available\n");
return -EBUSY;
}
if (ts < 0) {
LOGP(DRLCMAC, LOGL_NOTICE, "- Failed "
"to allocate a TS, no TFI available\n");
return -EBUSY;
}
pdch = &trx->pdch[ts];
/* The allocation will be successful, so the system state and tbf_/ms_
* may be modified from now on. */
if (tbf->direction == GPRS_RLCMAC_UL_TBF) {
struct gprs_rlcmac_ul_tbf *ul_tbf = as_ul_tbf(tbf_);
LOGP(DRLCMAC, LOGL_DEBUG, "- Assign uplink TS=%d TFI=%d USF=%d\n",
ts, tfi, usf);
assign_uplink_tbf_usf(pdch, ul_tbf, tfi, usf);
} else {
struct gprs_rlcmac_dl_tbf *dl_tbf = as_dl_tbf(tbf_);
LOGP(DRLCMAC, LOGL_DEBUG, "- Assign downlink TS=%d TFI=%d\n",
ts, tfi);
assign_dlink_tbf(pdch, dl_tbf, tfi);
}
tbf_->trx = trx;
/* the only one TS is the common TS */
tbf_->first_ts = tbf_->first_common_ts = ts;
ms_->set_reserved_slots(trx, 1 << ts, 1 << ts);
tbf_->upgrade_to_multislot = 0;
bts->bts->tbf_alloc_algo_a();
return 0;
}
/*! Compute capacity of a given TRX
*
* \param[in] trx Pointer to TRX object
* \param[in] rx_window Receive window
* \param[in] tx_window Transmit window
* \returns non-negative capacity
*/
static inline unsigned compute_capacity(const struct gprs_rlcmac_trx *trx, int rx_window, int tx_window)
{
const struct gprs_rlcmac_pdch *pdch;
unsigned ts, capacity = 0;
for (ts = 0; ts < ARRAY_SIZE(trx->pdch); ts++) {
pdch = &trx->pdch[ts];
if (rx_window & (1 << ts))
capacity += OSMO_MAX(32 - pdch->num_reserved(GPRS_RLCMAC_DL_TBF), 1);
/* Only consider common slots for UL */
if (tx_window & rx_window & (1 << ts)) {
if (find_free_usf(pdch->assigned_usf()) >= 0)
capacity += OSMO_MAX(32 - pdch->num_reserved(GPRS_RLCMAC_UL_TBF), 1);
}
}
return capacity;
}
/*! Find set of slots available for allocation while taking MS class into account
*
* \param[in] trx Pointer to TRX object
* \param[in] mslot_class The multislot class
* \param[in,out] ul_slots set of UL timeslots
* \param[in,out] dl_slots set of DL timeslots
* \returns negative error code or 0 on success
*/
int find_multi_slots(struct gprs_rlcmac_trx *trx, uint8_t mslot_class, uint8_t *ul_slots, uint8_t *dl_slots)
{
uint8_t Tx = mslot_class_get_tx(mslot_class), /* Max number of Tx slots */
Sum = mslot_class_get_sum(mslot_class); /* Max number of Tx + Rx slots */
int rx_window, tx_window, pdch_slots;
char slot_info[9] = {0};
int max_capacity = -1;
uint8_t max_ul_slots = 0, max_dl_slots = 0;
unsigned max_slots;
unsigned ul_ts, dl_ts;
unsigned num_tx;
unsigned mask_sel;
if (mslot_class)
LOGP(DRLCMAC, LOGL_DEBUG, "Slot Allocation (Algorithm B) for class %d\n",
mslot_class);
if (Tx == MS_NA) {
LOGP(DRLCMAC, LOGL_NOTICE, "Multislot class %d not applicable.\n",
mslot_class);
return -EINVAL;
}
max_slots = OSMO_MAX(mslot_class_get_rx(mslot_class), Tx);
if (*dl_slots == 0)
*dl_slots = 0xff;
if (*ul_slots == 0)
*ul_slots = 0xff;
pdch_slots = find_possible_pdchs(trx, max_slots, 0xff);
*dl_slots &= pdch_slots;
*ul_slots &= pdch_slots;
LOGP(DRLCMAC, LOGL_DEBUG, "- Possible DL/UL slots: (TS=0)\"%s\"(TS=7)\n",
set_flag_chars(set_flag_chars(set_flag_chars(slot_info,
*dl_slots, 'D', '.'),
*ul_slots, 'U'),
*ul_slots & *dl_slots, 'C'));
/* Check for each UL (TX) slot */
/* Iterate through possible numbers of TX slots */
for (num_tx = 1; num_tx <= mslot_class_get_tx(mslot_class); num_tx += 1) {
uint16_t tx_valid_win = (1 << num_tx) - 1;
uint8_t rx_mask[MASK_TR + 1];
mslot_fill_rx_mask(mslot_class, num_tx, rx_mask);
/* Rotate group of TX slots: UUU-----, -UUU----, ..., UU-----U */
for (ul_ts = 0; ul_ts < 8; ul_ts += 1, tx_valid_win <<= 1) {
unsigned tx_slot_count;
int max_rx;
uint16_t rx_valid_win;
uint32_t checked_rx[256/32] = {0};
/* Wrap valid window */
tx_valid_win = (tx_valid_win | tx_valid_win >> 8) & 0xff;
tx_window = tx_valid_win;
/* Filter out unavailable slots */
tx_window &= *ul_slots;
/* Skip if the the first TS (ul_ts) is not in the set */
if ((tx_window & (1 << ul_ts)) == 0)
continue;
/* Skip if the the last TS (ul_ts+num_tx-1) is not in the set */
if ((tx_window & (1 << ((ul_ts+num_tx-1) % 8))) == 0)
continue;
tx_slot_count = pcu_bitcount(tx_window);
max_rx = OSMO_MIN(mslot_class_get_rx(mslot_class), Sum - num_tx);
rx_valid_win = (1 << max_rx) - 1;
/* Rotate group of RX slots: DDD-----, -DDD----, ..., DD-----D */
for (dl_ts = 0; dl_ts < 8; dl_ts += 1, rx_valid_win <<= 1) {
/* Wrap valid window */
rx_valid_win = (rx_valid_win | rx_valid_win >> 8) & 0xff;
/* Validate with both Tta/Ttb/Trb and Ttb/Tra/Trb */
for (mask_sel = MASK_TT; mask_sel <= MASK_TR; mask_sel += 1) {
unsigned common_slot_count;
unsigned req_common_slots;
unsigned rx_slot_count;
uint16_t rx_bad;
uint8_t rx_good;
int capacity;
/* Filter out bad slots */
rx_bad = (uint16_t)(0xff & ~rx_mask[mask_sel]) << ul_ts;
rx_bad = (rx_bad | (rx_bad >> 8)) & 0xff;
rx_good = *dl_slots & ~rx_bad;
/* TODO: CHECK this calculation -> separate function for unit
* testing */
rx_window = rx_good & rx_valid_win;
rx_slot_count = pcu_bitcount(rx_window);
#if 0
LOGP(DRLCMAC, LOGL_DEBUG, "n_tx=%d, n_rx=%d, mask_sel=%d, "
"tx=%02x, rx=%02x, mask=%02x, bad=%02x, good=%02x, "
"ul=%02x, dl=%02x\n",
tx_slot_count, rx_slot_count, mask_sel,
tx_window, rx_window, rx_mask[mask_sel], rx_bad, rx_good,
*ul_slots, *dl_slots);
#endif
/* Check compliance with TS 45.002, table 6.4.2.2.1 */
/* Whether to skip this round doesn not only depend on the bit
* sets but also on mask_sel. Therefore this check must be done
* before doing the test_and_set_bit shortcut. */
if (mslot_class_get_type(mslot_class) == 1) {
unsigned slot_sum = rx_slot_count + tx_slot_count;
/* Assume down+up/dynamic.
* TODO: For ext-dynamic, down only, up only add more
* cases.
*/
if (slot_sum <= 6 && tx_slot_count < 3) {
if (mask_sel != MASK_TR)
/* Skip Tta */
continue;
} else if (slot_sum > 6 && tx_slot_count < 3) {
if (mask_sel != MASK_TT)
/* Skip Tra */
continue;
} else {
/* No supported row in table 6.4.2.2.1. */
#ifdef ENABLE_TS_ALLOC_DEBUG
LOGP(DRLCMAC, LOGL_DEBUG,
"- Skipping DL/UL slots: (TS=0)\"%s\"(TS=7), "
"combination not supported\n",
set_flag_chars(set_flag_chars(set_flag_chars(
slot_info,
rx_bad, 'x', '.'),
rx_window, 'D'),
tx_window, 'U'));
#endif
continue;
}
}
/* Avoid repeated RX combination check */
if (test_and_set_bit(checked_rx, rx_window))
continue;
if (!rx_good) {
#ifdef ENABLE_TS_ALLOC_DEBUG
LOGP(DRLCMAC, LOGL_DEBUG,
"- Skipping DL/UL slots: (TS=0)\"%s\"(TS=7), "
"no DL slots available\n",
set_flag_chars(set_flag_chars(slot_info,
rx_bad, 'x', '.'),
tx_window, 'U'));
#endif
continue;
}
if (!rx_window)
continue;
/* Check number of common slots according to TS 54.002, 6.4.2.2 */
common_slot_count = pcu_bitcount(tx_window & rx_window);
req_common_slots = OSMO_MIN(tx_slot_count, rx_slot_count);
if (mslot_class_get_type(mslot_class) == 1)
req_common_slots = OSMO_MIN(req_common_slots, 2);
if (req_common_slots != common_slot_count) {
#ifdef ENABLE_TS_ALLOC_DEBUG
LOGP(DRLCMAC, LOGL_DEBUG,
"- Skipping DL/UL slots: (TS=0)\"%s\"(TS=7), "
"invalid number of common TS: %d (expected %d)\n",
set_flag_chars(set_flag_chars(set_flag_chars(
slot_info,
rx_bad, 'x', '.'),
rx_window, 'D'),
tx_window, 'U'),
common_slot_count,
req_common_slots);
#endif
continue;
}
/* Compute capacity */
capacity = compute_capacity(trx, rx_window, tx_window);
#ifdef ENABLE_TS_ALLOC_DEBUG
LOGP(DRLCMAC, LOGL_DEBUG,
"- Considering DL/UL slots: (TS=0)\"%s\"(TS=7), "
"capacity = %d\n",
set_flag_chars(set_flag_chars(set_flag_chars(set_flag_chars(
slot_info,
rx_bad, 'x', '.'),
rx_window, 'D'),
tx_window, 'U'),
rx_window & tx_window, 'C'),
capacity);
#endif
if (capacity <= max_capacity)
continue;
max_capacity = capacity;
max_ul_slots = tx_window;
max_dl_slots = rx_window;
}
}
}
}
if (!max_ul_slots || !max_dl_slots) {
LOGP(DRLCMAC, LOGL_NOTICE,
"No valid UL/DL slot combination found\n");
return -EINVAL;
}
*ul_slots = max_ul_slots;
*dl_slots = max_dl_slots;
return 0;
}
/*! Count used bits in slots and reserved_slots bitmasks
*
* \param[in] slots Timeslots in use
* \param[in] reserved_slots Reserved timeslots
* \param[out] slotcount Number of TS in use
* \param[out] avail_count Number of reserved TS
*/
static void update_slot_counters(uint8_t slots, uint8_t reserved_slots, uint8_t *slotcount, uint8_t *avail_count)
{
(*slotcount) = pcu_bitcount(slots);
(*avail_count) = pcu_bitcount(reserved_slots);
}
/*! Return slot mask with single TS from a given UL/DL set according to TBF's direction, ts pointer is set to that TS
* number or to negative value on error
*
* \param[in] trx Pointer to TRX object
* \param[in] tbf Pointer to TBF object
* \param[in] dl_slots set of DL timeslots
* \param[in] ul_slots set of UL timeslots
* \param[in] ts corresponding TS or -1 for autoselection
* \returns slot mask with single UL or DL timeslot number if possible
*/
static uint8_t get_single_ts(const gprs_rlcmac_trx *trx, const gprs_rlcmac_tbf *tbf, uint8_t dl_slots, uint8_t ul_slots,
int ts)
{
uint8_t ret = dl_slots & ul_slots; /* Make sure to consider the first common slot only */
if (ts < 0)
ts = find_least_busy_pdch(trx, tbf->direction, ret, compute_usage_by_num_tbfs, NULL, NULL);
if (ts < 0)
return ffs(ret);
return ret & (1 << ts);
}
/*! Find set of timeslots available for allocation
*
* \param[in] trx Pointer to TRX object
* \param[in] tbf Pointer to TBF object
* \param[in] single Flag to force the single TS allocation
* \param[in] ul_slots set of UL timeslots
* \param[in] dl_slots set of DL timeslots
* \param[in] reserved_ul_slots set of reserved UL timeslots
* \param[in] reserved_dl_slots set of reserved DL timeslots
* \param[in] first_common_ts First TS common for both UL and DL or -1 if unknown
* \returns negative error code or selected TS on success
*/
static int tbf_select_slot_set(const gprs_rlcmac_tbf *tbf, const gprs_rlcmac_trx *trx, bool single,
uint8_t ul_slots, uint8_t dl_slots,
uint8_t reserved_ul_slots, uint8_t reserved_dl_slots,
int8_t first_common_ts)
{
uint8_t sl = tbf->direction != GPRS_RLCMAC_DL_TBF ? ul_slots : dl_slots;
char slot_info[9] = { 0 };
if (single)
sl = get_single_ts(trx, tbf, dl_slots, ul_slots, first_common_ts);
if (!sl) {
LOGP(DRLCMAC, LOGL_NOTICE, "No %s slots available\n",
tbf->direction != GPRS_RLCMAC_DL_TBF ? "uplink" : "downlink");
return -EINVAL;
}
if (tbf->direction != GPRS_RLCMAC_DL_TBF) {
snprintf(slot_info, 9, OSMO_BIT_SPEC, OSMO_BIT_PRINT_EX(reserved_ul_slots, 'u'));
masked_override_with(slot_info, sl, 'U');
LOGPC(DRLCMAC, LOGL_DEBUG, "- Selected UL");
} else {
snprintf(slot_info, 9, OSMO_BIT_SPEC, OSMO_BIT_PRINT_EX(reserved_dl_slots, 'd'));
masked_override_with(slot_info, sl, 'D');
LOGPC(DRLCMAC, LOGL_DEBUG, "- Selected DL");
}
LOGPC(DRLCMAC, LOGL_DEBUG, " slots: (TS=0)\"%s\"(TS=7)%s\n", slot_info, single ? ", single" : "");
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;
}
/*! Update MS' reserved timeslots
*
* \param[in,out] trx Pointer to TRX struct
* \param[in,out] ms_ Pointer to MS object
* \param[in] tbf_ Pointer to TBF struct
* \param[in] res_ul_slots Newly reserved UL slots
* \param[in] res_dl_slots Newly reserved DL slots
* \param[in] ul_slots available UL slots (for logging only)
* \param[in] dl_slots available DL slots (for logging only)
*/
static void update_ms_reserved_slots(gprs_rlcmac_trx *trx, GprsMs *ms, uint8_t res_ul_slots, uint8_t res_dl_slots,
uint8_t ul_slots, uint8_t dl_slots)
{
char slot_info[9] = { 0 };
if (res_ul_slots == ms->reserved_ul_slots() && res_dl_slots == ms->reserved_dl_slots())
return;
/* The reserved slots have changed, update the MS */
ms->set_reserved_slots(trx, res_ul_slots, res_dl_slots);
ts_format(slot_info, dl_slots, ul_slots);
LOGP(DRLCMAC, LOGL_DEBUG, "- Reserved DL/UL slots: (TS=0)\"%s\"(TS=7)\n", slot_info);
}
/*! Assign given UL timeslots to UL TBF
*
* \param[in,out] ul_tbf Pointer to UL TBF struct
* \param[in,out] trx Pointer to TRX object
* \param[in] ul_slots Set of slots to be assigned
* \param[in] tfi selected TFI
* \param[in] usf selected USF
*/
static void assign_ul_tbf_slots(struct gprs_rlcmac_ul_tbf *ul_tbf, gprs_rlcmac_trx *trx, uint8_t ul_slots, int tfi,
int *usf)
{
uint8_t ts;
for (ts = 0; ts < 8; ts++) {
if (!(ul_slots & (1 << ts)))
continue;
OSMO_ASSERT(usf[ts] >= 0);
LOGP(DRLCMAC, LOGL_DEBUG, "- Assigning UL TS %u\n", ts);
assign_uplink_tbf_usf(&trx->pdch[ts], ul_tbf, tfi, usf[ts]);
}
}
/*! Assign given DL timeslots to DL TBF
*
* \param[in,out] dl_tbf Pointer to DL TBF struct
* \param[in,out] trx Pointer to TRX object
* \param[in] ul_slots Set of slots to be assigned
* \param[in] tfi selected TFI
*/
static void assign_dl_tbf_slots(struct gprs_rlcmac_dl_tbf *dl_tbf, gprs_rlcmac_trx *trx, uint8_t dl_slots, int tfi)
{
uint8_t ts;
for (ts = 0; ts < 8; ts++) {
if (!(dl_slots & (1 << ts)))
continue;
LOGP(DRLCMAC, LOGL_DEBUG, "- Assigning DL TS %u\n", ts);
assign_dlink_tbf(&trx->pdch[ts], dl_tbf, tfi);
}
}
/*! Slot Allocation: Algorithm B
*
* Assign as many downlink slots as possible.
* Assign one uplink slot. (With free USF)
*
* \param[in,out] bts Pointer to BTS struct
* \param[in,out] ms_ Pointer to MS object
* \param[in,out] tbf_ Pointer to TBF struct
* \param[in] single flag indicating if we should force single-slot allocation
* \param[in] use_trx which TRX to use or -1 if it should be selected during allocation
* \returns negative error code or 0 on success
*/
int alloc_algorithm_b(struct gprs_rlcmac_bts *bts, GprsMs *ms_, struct gprs_rlcmac_tbf *tbf_, bool single,
int8_t use_trx)
{
uint8_t dl_slots;
uint8_t ul_slots;
uint8_t reserved_dl_slots;
uint8_t reserved_ul_slots;
int8_t first_common_ts;
uint8_t slotcount = 0;
uint8_t avail_count = 0, trx_no;
int first_ts = -1;
int usf[8] = {-1, -1, -1, -1, -1, -1, -1, -1};
int rc;
int tfi;
const GprsMs *ms = ms_;
const gprs_rlcmac_tbf *tbf = tbf_;
gprs_rlcmac_trx *trx;
/* Step 1: Get current state from the MS object */
if (!ms) {
LOGP(DRLCMAC, LOGL_ERROR, "MS not set\n");
return -EINVAL;
}
dl_slots = ms->reserved_dl_slots();
ul_slots = ms->reserved_ul_slots();
first_common_ts = ms->first_common_ts();
trx = ms->current_trx();
/* Step 2a: Find usable TRX and TFI */
tfi = tfi_find_free(bts->bts, trx, ms, tbf->direction, use_trx, &trx_no);
if (tfi < 0) {
LOGP(DRLCMAC, LOGL_NOTICE, "- Failed to allocate a TFI\n");
return tfi;
}
/* Step 2b: Reserve slots on the TRX for the MS */
if (!trx)
trx = &bts->trx[trx_no];
if (!dl_slots || !ul_slots) {
rc = find_multi_slots(trx, ms->ms_class(), &ul_slots, &dl_slots);
if (rc < 0)
return rc;
}
reserved_dl_slots = dl_slots;
reserved_ul_slots = ul_slots;
/* Step 3a: Derive the slot set for the current TBF */
rc = tbf_select_slot_set(tbf, trx, single, ul_slots, dl_slots, reserved_ul_slots, reserved_dl_slots,
first_common_ts);
if (rc < 0)
return -EINVAL;
first_ts = ffs(rc) - 1;
/* Step 3b: Derive the slot set for a given direction */
if (tbf->direction == GPRS_RLCMAC_DL_TBF) {
dl_slots = rc;
update_slot_counters(dl_slots, reserved_dl_slots, &slotcount, &avail_count);
} else {
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 = rc;
reserved_ul_slots = ul_slots;
update_slot_counters(ul_slots, reserved_ul_slots, &slotcount, &avail_count);
}
first_common_ts = ffs(dl_slots & ul_slots) - 1;
if (first_common_ts < 0) {
LOGP(DRLCMAC, LOGL_NOTICE, "No first common slots available\n");
return -EINVAL;
}
if (first_ts < 0) {
LOGP(DRLCMAC, LOGL_NOTICE, "No first slot available\n");
return -EINVAL;
}
if (single && slotcount) {
tbf_->upgrade_to_multislot = (avail_count > slotcount);
LOGP(DRLCMAC, LOGL_INFO, "Using single slot at TS %d for %s\n",
first_ts,
(tbf->direction == GPRS_RLCMAC_DL_TBF) ? "DL" : "UL");
} else {
tbf_->upgrade_to_multislot = 0;
LOGP(DRLCMAC, LOGL_INFO, "Using %d slots for %s\n", slotcount,
(tbf->direction == GPRS_RLCMAC_DL_TBF) ? "DL" : "UL");
}
/* The allocation will be successful, so the system state and tbf_/ms_
* may be modified from now on. */
/* Step 4: Update MS and TBF and really allocate the resources */
update_ms_reserved_slots(trx, ms_, reserved_ul_slots, reserved_dl_slots, ul_slots, dl_slots);
tbf_->trx = trx;
tbf_->first_common_ts = first_common_ts;
tbf_->first_ts = first_ts;
if (tbf->direction == GPRS_RLCMAC_DL_TBF)
assign_dl_tbf_slots(as_dl_tbf(tbf_), trx, dl_slots, tfi);
else
assign_ul_tbf_slots(as_ul_tbf(tbf_), trx, ul_slots, tfi, usf);
bts->bts->tbf_alloc_algo_b();
return 0;
}
/*! Slot Allocation: Algorithm dynamic
*
* This meta algorithm automatically selects on of the other algorithms based
* on the current system state.
*
* The goal is to support as many MS and TBF as possible. On low usage, the
* goal is to provide the highest possible bandwidth per MS.
*
* \param[in,out] bts Pointer to BTS struct
* \param[in,out] ms_ Pointer to MS object
* \param[in,out] tbf_ Pointer to TBF struct
* \param[in] single flag indicating if we should force single-slot allocation
* \param[in] use_trx which TRX to use or -1 if it should be selected during allocation
* \returns negative error code or 0 on success
*/
int alloc_algorithm_dynamic(struct gprs_rlcmac_bts *bts, GprsMs *ms_, struct gprs_rlcmac_tbf *tbf_, bool single,
int8_t use_trx)
{
int rc;
/* Reset load_is_high if there is at least one idle PDCH */
if (bts->multislot_disabled) {
bts->multislot_disabled = !idle_pdch_avail(bts);
if (!bts->multislot_disabled)
LOGP(DRLCMAC, LOGL_DEBUG, "Enabling algorithm B\n");
}
if (!bts->multislot_disabled) {
rc = alloc_algorithm_b(bts, ms_, tbf_, single, use_trx);
if (rc >= 0)
return rc;
if (!bts->multislot_disabled)
LOGP(DRLCMAC, LOGL_DEBUG, "Disabling algorithm B\n");
bts->multislot_disabled = 1;
}
return alloc_algorithm_a(bts, ms_, tbf_, single, use_trx);
}
int gprs_alloc_max_dl_slots_per_ms(const struct gprs_rlcmac_bts *bts, uint8_t ms_class)
{
int rx = mslot_class_get_rx(ms_class);
if (rx == MS_NA)
rx = 4;
if (bts->alloc_algorithm == alloc_algorithm_a)
return 1;
if (bts->multislot_disabled)
return 1;
return rx;
}
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