fixeria has uploaded this change for review. ( https://gerrit.osmocom.org/c/osmo-bsc/+/28326 )
Change subject: lchan_select: prepare a list of timeslots once, iterate over it ...................................................................... lchan_select: prepare a list of timeslots once, iterate over it The lchan_avail_by_type() attempts to find an unused lchan for the given GSM_LCHAN_* value: TCH/F, TCH/H, or SDCCH. This is achieved by looking up timeslots with compatible GSM_PCHAN_* values. For instance, finding an unused SDCCH lchan may involve: * attempt to find a timeslot with pchan=GSM_PCHAN_CCCH_SDCCH4, * attempt to find a timeslot with pchan=GSM_PCHAN_CCCH_SDCCH4_CBCH, * attempt to find a timeslot with pchan=GSM_PCHAN_SDCCH8_SACCH8C, * attempt to find a timeslot with pchan=GSM_PCHAN_SDCCH8_SACCH8C_CBCH, * attempt to find a timeslot with pchan=GSM_PCHAN_OSMO_DYN (switched), * attempt to find a timeslot with pchan=GSM_PCHAN_OSMO_DYN (not switched). Each attempt involves iterating over all timeslots of each TRX, either in ascending or in descending order (see _lc_dyn_find_bts() and _lc_find_trx()). This patch simplifies the lookup logic by preparing a monolithic array of timeslot pointers once, and then using that array for each GSM_PCHAN_* lookup attempt. This also facilitates adding more complex (than ascending/descending) allocation algorithms. Change-Id: I7ccc56856bfd40fd7c63b7437736de60c2b516ff Related: SYS#5460 --- M src/osmo-bsc/lchan_select.c 1 file changed, 81 insertions(+), 71 deletions(-) git pull ssh://gerrit.osmocom.org:29418/osmo-bsc refs/changes/26/28326/1 diff --git a/src/osmo-bsc/lchan_select.c b/src/osmo-bsc/lchan_select.c index ad45dc7..a322f07 100644 --- a/src/osmo-bsc/lchan_select.c +++ b/src/osmo-bsc/lchan_select.c @@ -2,7 +2,7 @@ * * (C) 2008 by Harald Welte <[email protected]> * (C) 2008, 2009 by Holger Hans Peter Freyther <[email protected]> - * (C) 2018 by sysmocom - s.f.m.c. GmbH <[email protected]> + * (C) 2018-2022 by sysmocom - s.f.m.c. GmbH <[email protected]> * * All Rights Reserved * @@ -30,6 +30,11 @@ #include <osmocom/bsc/lchan_select.h> #include <osmocom/bsc/bts.h> +struct lchan_select_ts_list { + struct gsm_bts_trx_ts **list; + unsigned int num; +}; + static struct gsm_lchan *pick_better_lchan(struct gsm_lchan *a, struct gsm_lchan *b) { if (!a) @@ -42,14 +47,13 @@ return a; } -static struct gsm_lchan * -_lc_find_trx(struct gsm_bts_trx *trx, enum gsm_phys_chan_config pchan, - enum gsm_phys_chan_config as_pchan, bool allow_pchan_switch, bool log) +static struct gsm_lchan *_lc_find(struct lchan_select_ts_list *ts_list, + enum gsm_phys_chan_config pchan, + enum gsm_phys_chan_config as_pchan, + bool allow_pchan_switch, bool log) { struct gsm_lchan *lchan; struct gsm_lchan *found_lchan = NULL; - struct gsm_bts_trx_ts *ts; - int j, start, stop, dir; #define LOGPLCHANALLOC(fmt, args...) do { \ if (log) \ @@ -61,28 +65,10 @@ ## args); \ } while (0) - if (!trx_is_usable(trx)) { - LOGPLCHANALLOC("%s trx not usable\n", gsm_trx_name(trx)); - return NULL; - } - - if (trx->bts->chan_alloc_reverse) { - /* check TS 7..0 */ - start = 7; - stop = -1; - dir = -1; - } else { - /* check TS 0..7 */ - start = 0; - stop = 8; - dir = 1; - } - - for (j = start; j != stop; j += dir) { + for (unsigned int tn = 0; tn < ts_list->num; tn++) { + struct gsm_bts_trx_ts *ts = ts_list->list[tn]; int lchans_as_pchan; - ts = &trx->ts[j]; - if (!ts_is_usable(ts)) - continue; + /* The caller first selects what kind of TS to search in, e.g. looking for exact * GSM_PCHAN_TCH_F, or maybe among dynamic GSM_PCHAN_OSMO_DYN... */ if (ts->pchan_on_init != pchan) { @@ -125,7 +111,7 @@ /* When picking an lchan with least interference, continue to loop across all lchans. When * ignoring interference levels, return the first match. */ - if (found_lchan && !trx->bts->chan_alloc_avoid_interf) + if (found_lchan && !ts->trx->bts->chan_alloc_avoid_interf) return found_lchan; } } @@ -141,44 +127,31 @@ #undef LOGPLCHANALLOC } -static struct gsm_lchan * -_lc_dyn_find_bts(struct gsm_bts *bts, enum gsm_phys_chan_config pchan, - enum gsm_phys_chan_config dyn_as_pchan, bool log) +static struct gsm_lchan *lc_dyn_find(struct lchan_select_ts_list *ts_list, + enum gsm_phys_chan_config pchan, + enum gsm_phys_chan_config dyn_as_pchan, + bool log) { - struct gsm_bts_trx *trx; - struct gsm_lchan *lc; - int allow_pchan_switch; - bool try_pchan_switch; + struct gsm_lchan *lchan; /* First find an lchan that needs no change in its timeslot pchan mode. * In particular, this ensures that handover to a dynamic timeslot in TCH/H favors timeslots that are currently * using only one of two TCH/H, so that we don't switch more dynamic timeslots to TCH/H than necessary. * For non-dynamic timeslots, it is not necessary to do a second pass with allow_pchan_switch == * true, because they never switch anyway. */ - try_pchan_switch = (pchan != dyn_as_pchan); - for (allow_pchan_switch = 0; allow_pchan_switch <= (try_pchan_switch ? 1 : 0); allow_pchan_switch++) { - if (bts->chan_alloc_reverse) { - llist_for_each_entry_reverse(trx, &bts->trx_list, list) { - lc = _lc_find_trx(trx, pchan, dyn_as_pchan, (bool)allow_pchan_switch, log); - if (lc) - return lc; - } - } else { - llist_for_each_entry(trx, &bts->trx_list, list) { - lc = _lc_find_trx(trx, pchan, dyn_as_pchan, (bool)allow_pchan_switch, log); - if (lc) - return lc; - } - } - } + if ((lchan = _lc_find(ts_list, pchan, dyn_as_pchan, false, log))) + return lchan; + if ((lchan = _lc_find(ts_list, pchan, dyn_as_pchan, true, log))) + return lchan; return NULL; } -static struct gsm_lchan * -_lc_find_bts(struct gsm_bts *bts, enum gsm_phys_chan_config pchan, bool log) +static struct gsm_lchan *lc_find(struct lchan_select_ts_list *ts_list, + enum gsm_phys_chan_config pchan, + bool log) { - return _lc_dyn_find_bts(bts, pchan, pchan, log); + return _lc_find(ts_list, pchan, pchan, false, log); } enum gsm_chan_t chan_mode_to_chan_type(enum gsm48_chan_mode chan_mode, enum channel_rate chan_rate) @@ -215,6 +188,35 @@ } } +static void populate_ts_list(struct lchan_select_ts_list *ts_list, + struct gsm_bts *bts, + bool log) +{ + struct gsm_bts_trx *trx; + unsigned int num = 0; + + llist_for_each_entry(trx, &bts->trx_list, list) { + for (unsigned int tn = 0; tn < ARRAY_SIZE(trx->ts); tn++) { + struct gsm_bts_trx_ts *ts = &trx->ts[tn]; + if (ts_is_usable(ts)) + ts_list->list[num++] = ts; + else if (log) + LOGP(DRLL, LOGL_DEBUG, "%s is not usable\n", gsm_ts_name(ts)); + } + } + + ts_list->num = num; + + /* Reverse the timeslot list if required */ + if (bts->chan_alloc_reverse) { + for (unsigned int tn = 0; tn < num / 2; tn++) { + struct gsm_bts_trx_ts *temp = ts_list->list[tn]; + ts_list->list[tn] = ts_list->list[num - tn - 1]; + ts_list->list[num - tn - 1] = temp; + } + } +} + struct gsm_lchan *lchan_select_by_chan_mode(struct gsm_bts *bts, enum gsm48_chan_mode chan_mode, enum channel_rate chan_rate) { @@ -228,10 +230,19 @@ { struct gsm_lchan *lchan = NULL; enum gsm_phys_chan_config first, first_cbch, second, second_cbch; + struct lchan_select_ts_list ts_list; if (log) LOG_BTS(bts, DRLL, LOGL_DEBUG, "lchan_avail_by_type(%s)\n", gsm_lchant_name(type)); + /* Allocate an array with pointers to all timeslots of a BTS */ + ts_list.list = talloc_array_ptrtype(bts, ts_list.list, bts->num_trx * 8); + if (OSMO_UNLIKELY(ts_list.list == NULL)) + return NULL; + + /* Populate this array with the actual pointers */ + populate_ts_list(&ts_list, bts, log); + switch (type) { case GSM_LCHAN_SDCCH: if (bts->chan_alloc_reverse) { @@ -246,46 +257,45 @@ second_cbch = GSM_PCHAN_SDCCH8_SACCH8C_CBCH; } - lchan = _lc_find_bts(bts, first, log); + lchan = lc_find(&ts_list, first, log); if (lchan == NULL) - lchan = _lc_find_bts(bts, first_cbch, log); + lchan = lc_find(&ts_list, first_cbch, log); if (lchan == NULL) - lchan = _lc_find_bts(bts, second, log); + lchan = lc_find(&ts_list, second, log); if (lchan == NULL) - lchan = _lc_find_bts(bts, second_cbch, log); + lchan = lc_find(&ts_list, second_cbch, log); /* No dedicated SDCCH available -- try fully dynamic * TCH/F_TCH/H_SDCCH8_PDCH if BTS supports it: */ if (lchan == NULL && osmo_bts_has_feature(&bts->features, BTS_FEAT_DYN_TS_SDCCH8)) - lchan = _lc_dyn_find_bts(bts, - GSM_PCHAN_OSMO_DYN, - GSM_PCHAN_SDCCH8_SACCH8C, log); + lchan = lc_dyn_find(&ts_list, GSM_PCHAN_OSMO_DYN, + GSM_PCHAN_SDCCH8_SACCH8C, log); break; case GSM_LCHAN_TCH_F: - lchan = _lc_find_bts(bts, GSM_PCHAN_TCH_F, log); + lchan = lc_find(&ts_list, GSM_PCHAN_TCH_F, log); /* If we don't have TCH/F available, try dynamic TCH/F_PDCH */ if (!lchan) - lchan = _lc_dyn_find_bts(bts, GSM_PCHAN_TCH_F_PDCH, - GSM_PCHAN_TCH_F, log); + lchan = lc_dyn_find(&ts_list, GSM_PCHAN_TCH_F_PDCH, + GSM_PCHAN_TCH_F, log); /* Try fully dynamic TCH/F_TCH/H_PDCH as TCH/F... */ if (!lchan && bts->network->dyn_ts_allow_tch_f) - lchan = _lc_dyn_find_bts(bts, - GSM_PCHAN_OSMO_DYN, - GSM_PCHAN_TCH_F, log); + lchan = lc_dyn_find(&ts_list, GSM_PCHAN_OSMO_DYN, + GSM_PCHAN_TCH_F, log); break; case GSM_LCHAN_TCH_H: - lchan = _lc_find_bts(bts, GSM_PCHAN_TCH_H, log); + lchan = lc_find(&ts_list, GSM_PCHAN_TCH_H, log); /* No dedicated TCH/x available -- try fully dynamic * TCH/F_TCH/H_PDCH */ if (!lchan) - lchan = _lc_dyn_find_bts(bts, - GSM_PCHAN_OSMO_DYN, - GSM_PCHAN_TCH_H, log); + lchan = lc_dyn_find(&ts_list, GSM_PCHAN_OSMO_DYN, + GSM_PCHAN_TCH_H, log); break; default: LOG_BTS(bts, DRLL, LOGL_ERROR, "Unknown gsm_chan_t %u\n", type); } + talloc_free(ts_list.list); + return lchan; } -- To view, visit https://gerrit.osmocom.org/c/osmo-bsc/+/28326 To unsubscribe, or for help writing mail filters, visit https://gerrit.osmocom.org/settings Gerrit-Project: osmo-bsc Gerrit-Branch: master Gerrit-Change-Id: I7ccc56856bfd40fd7c63b7437736de60c2b516ff Gerrit-Change-Number: 28326 Gerrit-PatchSet: 1 Gerrit-Owner: fixeria <[email protected]> Gerrit-MessageType: newchange
