pespin has submitted this change. ( https://gerrit.osmocom.org/c/osmo-bsc/+/27885 )

Change subject: paging: Submit up to 20 paging requests in a single work iteration ......................................................................

paging: Submit up to 20 paging requests in a single work iteration

Having one paging request being sent every PAGING_TIMER (500msec) is too slow in case BSC is serving lots of subscribers on a BTS. Hence, we want to send many paging requests at once while still trying not to fill the BTS buffer. Morever, we don't want to send tons of paging requests at once, hence we limit the amount of paging requests sent in one timer iteration (MAX_PAGE_REQ_PER_ITER) in order to avoid the BSC doing lots of work there at once, keeping it busy from processing other tasks.

Related: SYS#5922 Change-Id: I609fa67834b426456f48f6fb2acb601c5905f178 --- M src/osmo-bsc/paging.c 1 file changed, 48 insertions(+), 34 deletions(-)

Approvals: laforge: Looks good to me, but someone else must approve fixeria: Looks good to me, but someone else must approve pespin: Looks good to me, approved Jenkins Builder: Verified

diff --git a/src/osmo-bsc/paging.c b/src/osmo-bsc/paging.c index 898fa95..f81713e 100644 --- a/src/osmo-bsc/paging.c +++ b/src/osmo-bsc/paging.c @@ -60,6 +60,9 @@

#define PAGING_TIMER 0, 500000

+/* How many paging requests to Tx on RSL at max before going back to main loop */ +#define MAX_PAGE_REQ_PER_ITER 20 + /* * Kill one paging request update the internal list... */ @@ -182,7 +185,8 @@ */ static void paging_handle_pending_requests(struct gsm_bts_paging_state *paging_bts) { - struct gsm_paging_request *request = NULL; + struct gsm_paging_request *request, *initial_request; + unsigned int num_paged = 0;

/* * Determine if the pending_requests list is empty and @@ -193,43 +197,53 @@ return; }

- /* - * In case the BTS does not provide us with load indication and we - * ran out of slots, call an autofill routine. It might be that the - * BTS did not like our paging messages and then we have counted down - * to zero and we do not get any messages. - */ - if (paging_bts->available_slots == 0) { - osmo_timer_schedule(&paging_bts->credit_timer, 5, 0); - return; - } - - request = llist_first_entry(&paging_bts->pending_requests, - struct gsm_paging_request, entry); - - /* we need to determine the number of free channels */ - if (paging_bts->free_chans_need != -1 && - can_send_pag_req(request->bts, request->chan_type) != 0) { - LOG_PAGING_BTS(request, request->bts, DPAG, LOGL_INFO, - "Paging delayed: not enough free channels (<%d)\n", - paging_bts->free_chans_need); - goto skip_paging; - } - /* Skip paging if the bts is down. */ - if (!request->bts->oml_link) - goto skip_paging; + if (!paging_bts->bts->oml_link) + goto sched_next_iter;

- /* handle the paging request now */ - page_ms(request); - paging_bts->available_slots--; - request->attempts++; + /* do while loop: Try send at most first MAX_PAGE_REQ_PER_ITER paging + * requests (or before if there are no more available slots). Since + * transmitted requests are re-appended at the end of the list, we check + * until we find the first req again, in order to avoid retransmitting + * repeated requests until next time paging is scheduled. */ + initial_request = llist_first_entry(&paging_bts->pending_requests, + struct gsm_paging_request, entry); + request = initial_request; + do { + /* + * In case the BTS does not provide us with load indication and we + * ran out of slots, call an autofill routine. It might be that the + * BTS did not like our paging messages and then we have counted down + * to zero and we do not get any messages. + */ + if (paging_bts->available_slots == 0) { + osmo_timer_schedule(&paging_bts->credit_timer, 5, 0); + return; + }

- /* take the current and add it to the back */ - llist_del(&request->entry); - llist_add_tail(&request->entry, &paging_bts->pending_requests); + /* we need to determine the number of free channels */ + if (paging_bts->free_chans_need != -1 && + can_send_pag_req(request->bts, request->chan_type) != 0) { + LOG_PAGING_BTS(request, request->bts, DPAG, LOGL_INFO, + "Paging delayed: not enough free channels (<%d)\n", + paging_bts->free_chans_need); + goto sched_next_iter; + }

-skip_paging: + /* handle the paging request now */ + page_ms(request); + paging_bts->available_slots--; + request->attempts++; + num_paged++; + + llist_del(&request->entry); + llist_add_tail(&request->entry, &paging_bts->pending_requests); + request = llist_first_entry(&paging_bts->pending_requests, + struct gsm_paging_request, entry); + } while (request != initial_request && num_paged < MAX_PAGE_REQ_PER_ITER); + + /* Once done iterating, prepare next scheduling: */ +sched_next_iter: osmo_timer_schedule(&paging_bts->work_timer, PAGING_TIMER); }