gbproxy: Implement scaling of BVC flow control in SGSN pool
When there are multiple SGSNs inside a pool, we need to decide
how much of the per-BVC capacity advertised by the BSS in its
BVC-FLOW-CONTROL we should announce to each of the pool members.
A conservative approach would be to advertise 1/num_sgsn, but
there may also be use case where over-provisioning (announcing more
than an equal share of the capacity) is useful.
Hence, let's introduce "pool bvc-flow-control-ratio <1-100>" in order
to allow the administrator to decide.
Related: OS#4891
Change-Id: Ibe5addf657e7237499ca0205bacfe999ecd1e771
diff --git a/src/gbproxy/gb_proxy.c b/src/gbproxy/gb_proxy.c
index a976d25..53aecdf 100644
--- a/src/gbproxy/gb_proxy.c
+++ b/src/gbproxy/gb_proxy.c
@@ -40,6 +40,7 @@
#include <osmocom/gprs/gprs_ns2.h>
#include <osmocom/gprs/gprs_bssgp.h>
+#include <osmocom/gprs/gprs_bssgp2.h>
#include <osmocom/gprs/gprs_bssgp_bss.h>
#include <osmocom/gprs/bssgp_bvc_fsm.h>
@@ -566,15 +567,28 @@
/* BVC FSM informs us about BVC-FC PDU receive */
static void bss_ptp_bvc_fc_bvc(uint16_t nsei, uint16_t bvci, const struct bssgp2_flow_ctrl *fc, void *priv)
{
+ struct bssgp2_flow_ctrl fc_reduced;
struct gbproxy_bvc *bss_bvc = priv;
- struct gbproxy_cell *cell = bss_bvc->cell;
+ struct gbproxy_cell *cell;
+ struct gbproxy_config *cfg;
+ OSMO_ASSERT(bss_bvc);
+ OSMO_ASSERT(fc);
+
+ cell = bss_bvc->cell;
if (!cell)
return;
- /* FIXME: actually split the bandwidth among the SGSNs! */
+ cfg = cell->cfg;
- dispatch_to_all_sgsn_bvc(cell, BSSGP_BVCFSM_E_REQ_FC_BVC, (void *) fc);
+ /* reduce / scale according to configuration to make sure we only advertise a fraction
+ * of the capacity to each of the SGSNs in the pool */
+ fc_reduced = *fc;
+ fc_reduced.bucket_size_max = (fc->bucket_size_max * cfg->pool.bvc_fc_ratio) / 100;
+ fc_reduced.bucket_leak_rate = (fc->bucket_leak_rate * cfg->pool.bvc_fc_ratio) / 100;
+ /* we don't modify the per-MS related values as any single MS is only served by one SGSN */
+
+ dispatch_to_all_sgsn_bvc(cell, BSSGP_BVCFSM_E_REQ_FC_BVC, (void *) &fc_reduced);
}
static const struct bssgp_bvc_fsm_ops bss_ptp_bvc_fsm_ops = {
@@ -1270,6 +1284,8 @@
{
struct timespec tp;
+ /* by default we advertise 100% of the BSS-side capacity to _each_ SGSN */
+ cfg->pool.bvc_fc_ratio = 100;
hash_init(cfg->bss_nses);
cfg->ctrg = rate_ctr_group_alloc(tall_sgsn_ctx, &global_ctrg_desc, 0);
if (!cfg->ctrg) {