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authorAndreas Eversberg <jolly@eversberg.eu>2013-10-11 13:33:59 +0200
committerAndreas Eversberg <jolly@eversberg.eu>2013-10-11 13:33:59 +0200
commit1c8a3d828612a6bea343a268072a7dddf4a22480 (patch)
tree59fbd4220ead81b03a9725533c4a96b16f841268 /openbsc/src/libbsc/pdch_defrag.c
parent0e40c97a76ffcf071e918e1b906cdee41cb9d48e (diff)
dyn PDCH: Add algorithm to defragment shared TCH/F+PDCH channelsjolly/dyn_pdch
This algorithm ensures that gaps between active TCH/F+PDCH channels are removed, by assigning active connections to standard TCH/F or by assigning them to consecutive TCH/F+PDCH channels.
Diffstat (limited to 'openbsc/src/libbsc/pdch_defrag.c')
-rw-r--r--openbsc/src/libbsc/pdch_defrag.c183
1 files changed, 183 insertions, 0 deletions
diff --git a/openbsc/src/libbsc/pdch_defrag.c b/openbsc/src/libbsc/pdch_defrag.c
new file mode 100644
index 000000000..5f075f65d
--- /dev/null
+++ b/openbsc/src/libbsc/pdch_defrag.c
@@ -0,0 +1,183 @@
+/* (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 <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_shared_forward(struct gsm_bts *bts)
+{
+ struct gsm_bts_trx *trx;
+ struct gsm_lchan *lc;
+ int j;
+
+ llist_for_each_entry(trx, &bts->trx_list, list) {
+ for (j = 0; j < 8; j++) {
+ /* find first TCH/F+PDCH */
+ if (trx->ts[j].pchan == GSM_PCHAN_TCH_F_PDCH) {
+ lc = &trx->ts[j].lchan[0];
+ if (lc->state == LCHAN_S_ACTIVE)
+ return lc;
+ }
+ }
+ }
+
+ return NULL;
+}
+
+static struct gsm_lchan *find_shared_reverse(struct gsm_bts *bts)
+{
+ struct gsm_bts_trx *trx;
+ struct gsm_lchan *lc;
+ int j;
+
+ llist_for_each_entry_reverse(trx, &bts->trx_list, list) {
+ for (j = 7; j >= 0; j--) {
+ /* find last TCH/F+PDCH */
+ if (trx->ts[j].pchan == GSM_PCHAN_TCH_F_PDCH) {
+ lc = &trx->ts[j].lchan[0];
+ if (lc->state == LCHAN_S_ACTIVE)
+ return lc;
+ }
+ }
+ }
+
+ return NULL;
+}
+
+static void debug_bts_trx_ts(struct gsm_bts_trx_ts *ts)
+{
+ LOGPC(DHODEC, LOGL_DEBUG, " (BTS %u, TRX %u, TS %u)\n",
+ ts->trx->bts->nr, ts->trx->nr, ts->nr);
+}
+
+/* Try to move a TCH/F+PDCH candidate to maintain as much free and consecutive
+ * GSM_PCHAN_TCH_F_PDCH slots as possible.
+ *
+ * This algorithm is triggered whenever a channel has been released.
+ *
+ * The last (highest TRX/TS number) and active TCH/F+PDCH is searched. If there
+ * is a TCH/F or a free TCH/F+PDCH on a lower TRX/TS number, assignment is
+ * triggered. (When allocation order is reversed, this algorithm handles TRX/TS
+ * numbers in reversed order also.
+ *
+ * This algorithm ensures that gaps between active TCH/F+PDCH channels are
+ * removed, by assigning active connections to standard TCH/F or by assigning
+ * them to consecutive TCH/F+PDCH channels.
+ */
+void do_pdch_defrag(struct gsm_bts *bts)
+{
+ struct gsm_lchan *old_lchan = NULL, *new_lchan;
+ int rc;
+
+ /* search TCH/F+PDCH in reverse order of allocation */
+ if (bts->chan_alloc_reverse) {
+ /* search from first to last TRX/TS */
+ old_lchan = find_shared_forward(bts);
+ } else {
+ /* search from last to first TRX/TS */
+ old_lchan = find_shared_reverse(bts);
+ }
+
+ /* if there is no candidate on GSM_PCHAN_TCH_F_PDCH, we are done */
+ if (!old_lchan)
+ return;
+
+ LOGP(DHODEC, LOGL_DEBUG, "A shared TCH/F+PDCH is in use, check if we "
+ "can move connection.");
+ debug_bts_trx_ts(old_lchan->ts);
+
+ /* allocate new lchan */
+ new_lchan = lchan_alloc(bts, GSM_LCHAN_TCH_F, 0);
+ /* no free destination for candidate */
+ if (!new_lchan) {
+ LOGP(DHODEC, LOGL_DEBUG, "-> 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) {
+ LOGP(DHODEC, LOGL_DEBUG, "-> New channel for candidate is also "
+ "a TCH/F+PDCH.");
+ debug_bts_trx_ts(new_lchan->ts);
+ /* be sure to move down (or up at reverse allocation) */
+ if (bts->chan_alloc_reverse) {
+ /* new TS is lower */
+ if (new_lchan->ts->trx->nr < old_lchan->ts->trx->nr) {
+ LOGP(DHODEC, LOGL_DEBUG, "-> Move does not "
+ "lower fragmentation, new TRX has "
+ "lower number.\n");
+ goto free_lchan;
+ }
+ if (new_lchan->ts->trx->nr == old_lchan->ts->trx->nr
+ && new_lchan->ts->nr < old_lchan->ts->nr) {
+ LOGP(DHODEC, LOGL_DEBUG, "-> Move does not "
+ "lower fragmentation, new TS has "
+ "lower number.\n");
+ goto free_lchan;
+ }
+ } else {
+ /* new TS is higher */
+ if (new_lchan->ts->trx->nr > old_lchan->ts->trx->nr) {
+ goto free_lchan;
+ LOGP(DHODEC, LOGL_DEBUG, "-> Move does not "
+ "lower fragmentation, new TRX has "
+ "higher number.\n");
+ }
+ if (new_lchan->ts->trx->nr == old_lchan->ts->trx->nr
+ && new_lchan->ts->nr > old_lchan->ts->nr) {
+ LOGP(DHODEC, LOGL_DEBUG, "-> Move does not "
+ "lower fragmentation, new TS has "
+ "higher number.\n");
+ goto free_lchan;
+ }
+ }
+ } else {
+ LOGP(DHODEC, LOGL_DEBUG, "-> New channel for candidate is a "
+ "TCH/F.");
+ debug_bts_trx_ts(new_lchan->ts);
+ }
+
+ rc = bsc_handover_start(old_lchan, new_lchan, new_lchan->ts->trx->bts,
+ 1);
+ 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 check, if assignment is ongoing or if it fails,
+ * because in both cases a channel is freed, so this defragmentation
+ * is triggered again.
+ */
+
+ return;
+
+free_lchan:
+ lchan_free(new_lchan);
+}
+