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/* (C) 2013 by Andreas Eversberg <andreas@eversberg.eu>
*
* All Rights Reserved
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU Affero General Public License as published by
* the Free Software Foundation; either version 3 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 Affero General Public License for more details.
*
* You should have received a copy of the GNU Affero General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*
*/
#include <stdlib.h>
#include <stdbool.h>
#include <errno.h>
#include <openbsc/debug.h>
#include <openbsc/gsm_data.h>
#include <openbsc/handover.h>
#include <openbsc/pdch_defrag.h>
#include <openbsc/chan_alloc.h>
static struct gsm_lchan *find_lchan(struct gsm_bts *bts,
enum gsm_phys_chan_config type,
bool forward)
{
struct gsm_bts_trx *trx;
struct gsm_lchan *lc;
int i, start, stop, dir;
if (forward) {
/* check TS 0..7 */
start = 0;
stop = 8;
dir = 1;
} else {
/* check TS 7..0 */
start = 7;
stop = -1;
dir = -1;
}
llist_for_each_entry(trx, &bts->trx_list, list) {
for (i = start; i != stop; i += dir) {
if (trx->ts[i].pchan == type) {
lc = &trx->ts[i].lchan[0];
if (lc->state == LCHAN_S_ACTIVE)
return lc;
}
}
}
return NULL;
}
#define LOGTSP(ss, ll, ts, fmt, args...) \
LOGP(ss, ll, "(BTS %u, TRX %u, TS %u) " fmt, \
ts->trx->bts->nr, ts->trx->nr, ts->nr, \
##args)
/* Defragment TCH/F+PDCH channels to remove gaps between active
* GSM_PCHAN_TCH_F_PDCH slots. Assign active connections to standard TCH/F or
* to consecutive TCH/F+PDCH channels.
*
* This function depends on being re-triggered whenever a channel has been
* released: each reassignment for defragmentation includes a channel release,
* which should trigger another invocation, and defragmentation will continue.
*
* Look up the last active TCH/F+PDCH (highest TRX/TS number). If there
* is a TCH/F or a free TCH/F+PDCH on a lower TRX/TS number, re-assign it.
* If allocation order is reversed, re-assign in reverse direction instead.
*/
void do_pdch_defrag(struct gsm_bts *bts)
{
struct gsm_lchan *old_lchan = NULL, *new_lchan;
int rc;
int want_dir;
int is_dir;
/* Find the "last" lchan in use, according to chan_alloc_reverse: if
* reversed, find the highest-numbered lchan == start looking from the
* back. */
old_lchan = find_lchan(bts, GSM_PCHAN_TCH_F_PDCH,
bts->chan_alloc_reverse? true : false);
/* if there is no candidate on GSM_PCHAN_TCH_F_PDCH, we are done */
/* FIXME: for multi-TRX, if the first TRX's last lchan doesn't need
* re-assignment, the other TRXes are not going to be checked. */
if (!old_lchan)
return;
LOGTSP(DHODEC, LOGL_DEBUG, old_lchan->ts,
"A shared TCH/F+PDCH is in use, check for reassignment.\n");
/* allocate new lchan */
new_lchan = lchan_alloc(bts, GSM_LCHAN_TCH_F, 0);
/* no free destination for candidate */
if (!new_lchan) {
LOGTSP(DHODEC, LOGL_DEBUG, old_lchan->ts,
"-> Cannot move, no other TCH/F available.\n");
return;
}
/* if new TS is also a GSM_PCHAN_TCH_F_PDCH */
if (new_lchan->ts->pchan == GSM_PCHAN_TCH_F_PDCH) {
LOGTSP(DHODEC, LOGL_DEBUG, new_lchan->ts,
"<- New channel for candidate is also a TCH/F+PDCH.\n");
/* be sure to move to lower number (or to higher number in case
* of reverse allocation) */
want_dir = bts->chan_alloc_reverse ? 1 : -1;
is_dir = new_lchan->ts->trx->nr - old_lchan->ts->trx->nr;
if (is_dir == 0) {
/* TRX number stays the same, check TS numbers. */
is_dir = new_lchan->ts->nr - old_lchan->ts->nr;
}
/* If is_dir were 0 here, new_lchan == old_lchan, which should
* never happen. Even if it does, that would mean no decrease
* in fragmentation... */
if ((is_dir > 0) != (want_dir > 0)) {
LOGP(DHODEC, LOGL_DEBUG,
"-> Move does not lower fragmentation:"
" TRX %u TS %u to TRX %u TS %u%s\n",
old_lchan->ts->trx->nr, old_lchan->ts->nr,
new_lchan->ts->trx->nr, new_lchan->ts->nr,
bts->chan_alloc_reverse ? " (reverse allocation)" : "");
lchan_free(new_lchan);
return;
}
} else {
LOGTSP(DHODEC, LOGL_DEBUG, new_lchan->ts,
"<- New channel for candidate is a TCH/F.\n");
}
rc = bsc_handover_start(old_lchan, new_lchan, new_lchan->ts->trx->bts);
if (rc) {
LOGP(DHODEC, LOGL_NOTICE,
"Cannot trigger assignment to defragment TCH/F+PDCH slots.\n");
} else {
LOGP(DHODEC, LOGL_NOTICE,
"Triggered assignment to defragment TCH/F+PDCH slots.\n");
}
/* We do not need to take further action here regardless of
* re-assignment success or failure, because in both cases a channel is
* freed, and this defragmentation should be triggered again.
*/
/* FIXME: does re-assignment failure mean infinite looping/recursion!? */
}
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