<p>fixeria has uploaded this change for <strong>review</strong>.</p><p><a href="https://gerrit.osmocom.org/c/osmo-bts/+/24323">View Change</a></p><pre style="font-family: monospace,monospace; white-space: pre-wrap;">[VAMOS] osmo-bts-trx: rework and split up bts_sched_fn()<br><br>Currently, in bts_sched_fn() we send a Downlink burst to the PHY<br>immediately after calling the associated logical channel handler.<br>Together with the obvious performance advantages, this approach<br>imposes some serious limitations. The code has already become<br>quite complex with the introduction of the baseband frequency<br>hopping, and now it's not possible anymore to extend it further.<br><br>TRXD PDU batching, which is essential for VAMOS implementation,<br>requires us to make the scheduler more flexible at the expense of<br>increased memory consumption and additional CPU cycles. This patch<br>splits up Downlink burst scheduling into 3 main steps:<br><br> 1. bts_sched_init_buffers(): initialization of per-TRX Downlink<br> burst buffers allocated by phy_instance_create(). For C0/TRX0<br> all timeslots are pre-initialized with dummy burst.<br> 2. bts_sched_fn(): generating burst bits for all active lchans.<br> 3. bts_sched_flush_buffers(): sending everything to the PHY.<br><br>This approach allows us to a) get rid of the ugly tail in bts_sched_fn()<br>that was responsible for sending dummy bursts on C0/TRX0; b) implement<br>the PDU batching and have several variants of bts_sched_flush_buffers()<br>providing the alternative batching approaches later on; c) implement<br>PDU merging for the upcoming shadow transceivers.<br><br>Change-Id: Iec78989517865b3275a9784d1042a5ebd1d2815f<br>Related: SYS#4895, OS#4941<br>---<br>M include/osmo-bts/phy_link.h<br>M src/osmo-bts-trx/scheduler_trx.c<br>2 files changed, 76 insertions(+), 51 deletions(-)<br><br></pre><pre style="font-family: monospace,monospace; white-space: pre-wrap;">git pull ssh://gerrit.osmocom.org:29418/osmo-bts refs/changes/23/24323/1</pre><pre style="font-family: monospace,monospace; white-space: pre-wrap;"><span>diff --git a/include/osmo-bts/phy_link.h b/include/osmo-bts/phy_link.h</span><br><span>index c4b60f3..bc934ec 100644</span><br><span>--- a/include/osmo-bts/phy_link.h</span><br><span>+++ b/include/osmo-bts/phy_link.h</span><br><span>@@ -113,6 +113,7 @@</span><br><span> struct {</span><br><span> struct trx_l1h *hdl;</span><br><span> bool sw_act_reported;</span><br><span style="color: hsl(120, 100%, 40%);">+ struct trx_dl_burst_req br[TRX_NR_TS];</span><br><span> } osmotrx;</span><br><span> struct {</span><br><span> /* logical transceiver number within one PHY */</span><br><span>diff --git a/src/osmo-bts-trx/scheduler_trx.c b/src/osmo-bts-trx/scheduler_trx.c</span><br><span>index c90a0a3..2a37abb 100644</span><br><span>--- a/src/osmo-bts-trx/scheduler_trx.c</span><br><span>+++ b/src/osmo-bts-trx/scheduler_trx.c</span><br><span>@@ -3,6 +3,7 @@</span><br><span> /* (C) 2013 by Andreas Eversberg <jolly@eversberg.eu></span><br><span> * (C) 2015 by Alexander Chemeris <Alexander.Chemeris@fairwaves.co></span><br><span> * (C) 2015-2017 by Harald Welte <laforge@gnumonks.org></span><br><span style="color: hsl(120, 100%, 40%);">+ * (C) 2020-2021 by sysmocom - s.m.f.c. GmbH <info@sysmocom.de></span><br><span> *</span><br><span> * All Rights Reserved</span><br><span> *</span><br><span>@@ -92,19 +93,72 @@</span><br><span> return NULL;</span><br><span> }</span><br><span> </span><br><span style="color: hsl(120, 100%, 40%);">+static void bts_sched_init_buffers(struct gsm_bts *bts, const uint32_t fn)</span><br><span style="color: hsl(120, 100%, 40%);">+{</span><br><span style="color: hsl(120, 100%, 40%);">+ struct gsm_bts_trx *trx;</span><br><span style="color: hsl(120, 100%, 40%);">+ uint8_t tn;</span><br><span style="color: hsl(120, 100%, 40%);">+</span><br><span style="color: hsl(120, 100%, 40%);">+ llist_for_each_entry(trx, &bts->trx_list, list) {</span><br><span style="color: hsl(120, 100%, 40%);">+ struct phy_instance *pinst = trx->pinst;</span><br><span style="color: hsl(120, 100%, 40%);">+ const struct phy_link *plink = pinst->phy_link;</span><br><span style="color: hsl(120, 100%, 40%);">+</span><br><span style="color: hsl(120, 100%, 40%);">+ /* Advance frame number, so the PHY has more time to process bursts */</span><br><span style="color: hsl(120, 100%, 40%);">+ const uint32_t sched_fn = GSM_TDMA_FN_SUM(fn, plink->u.osmotrx.clock_advance);</span><br><span style="color: hsl(120, 100%, 40%);">+</span><br><span style="color: hsl(120, 100%, 40%);">+ for (tn = 0; tn < ARRAY_SIZE(trx->ts); tn++) {</span><br><span style="color: hsl(120, 100%, 40%);">+ struct trx_dl_burst_req *br = &pinst->u.osmotrx.br[tn];</span><br><span style="color: hsl(120, 100%, 40%);">+</span><br><span style="color: hsl(120, 100%, 40%);">+ *br = (struct trx_dl_burst_req) {</span><br><span style="color: hsl(120, 100%, 40%);">+ .trx_num = trx->nr,</span><br><span style="color: hsl(120, 100%, 40%);">+ .fn = sched_fn,</span><br><span style="color: hsl(120, 100%, 40%);">+ .tn = tn,</span><br><span style="color: hsl(120, 100%, 40%);">+ };</span><br><span style="color: hsl(120, 100%, 40%);">+ }</span><br><span style="color: hsl(120, 100%, 40%);">+ }</span><br><span style="color: hsl(120, 100%, 40%);">+</span><br><span style="color: hsl(120, 100%, 40%);">+ /* Initialize all timeslots on C0/TRX0 with dummy burst */</span><br><span style="color: hsl(120, 100%, 40%);">+ for (tn = 0; tn < ARRAY_SIZE(trx->ts); tn++) {</span><br><span style="color: hsl(120, 100%, 40%);">+ struct phy_instance *pinst = bts->c0->pinst;</span><br><span style="color: hsl(120, 100%, 40%);">+ struct trx_dl_burst_req *br = &pinst->u.osmotrx.br[tn];</span><br><span style="color: hsl(120, 100%, 40%);">+</span><br><span style="color: hsl(120, 100%, 40%);">+ memcpy(br->burst, _sched_dummy_burst, GSM_BURST_LEN);</span><br><span style="color: hsl(120, 100%, 40%);">+ br->burst_len = GSM_BURST_LEN;</span><br><span style="color: hsl(120, 100%, 40%);">+ }</span><br><span style="color: hsl(120, 100%, 40%);">+}</span><br><span style="color: hsl(120, 100%, 40%);">+</span><br><span style="color: hsl(120, 100%, 40%);">+static void bts_sched_flush_buffers(struct gsm_bts *bts)</span><br><span style="color: hsl(120, 100%, 40%);">+{</span><br><span style="color: hsl(120, 100%, 40%);">+ const struct gsm_bts_trx *trx;</span><br><span style="color: hsl(120, 100%, 40%);">+ unsigned int tn;</span><br><span style="color: hsl(120, 100%, 40%);">+</span><br><span style="color: hsl(120, 100%, 40%);">+ llist_for_each_entry(trx, &bts->trx_list, list) {</span><br><span style="color: hsl(120, 100%, 40%);">+ const struct phy_instance *pinst = trx->pinst;</span><br><span style="color: hsl(120, 100%, 40%);">+ struct trx_l1h *l1h = pinst->u.osmotrx.hdl;</span><br><span style="color: hsl(120, 100%, 40%);">+</span><br><span style="color: hsl(120, 100%, 40%);">+ for (tn = 0; tn < TRX_NR_TS; tn++) {</span><br><span style="color: hsl(120, 100%, 40%);">+ const struct trx_dl_burst_req *br;</span><br><span style="color: hsl(120, 100%, 40%);">+</span><br><span style="color: hsl(120, 100%, 40%);">+ br = &pinst->u.osmotrx.br[tn];</span><br><span style="color: hsl(120, 100%, 40%);">+ if (!br->burst_len)</span><br><span style="color: hsl(120, 100%, 40%);">+ continue;</span><br><span style="color: hsl(120, 100%, 40%);">+ trx_if_send_burst(l1h, br);</span><br><span style="color: hsl(120, 100%, 40%);">+ }</span><br><span style="color: hsl(120, 100%, 40%);">+ }</span><br><span style="color: hsl(120, 100%, 40%);">+}</span><br><span style="color: hsl(120, 100%, 40%);">+</span><br><span> /* schedule all frames of all TRX for given FN */</span><br><span> static void bts_sched_fn(struct gsm_bts *bts, const uint32_t fn)</span><br><span> {</span><br><span style="color: hsl(0, 100%, 40%);">- struct trx_dl_burst_req br;</span><br><span> struct gsm_bts_trx *trx;</span><br><span style="color: hsl(0, 100%, 40%);">- uint8_t c0_mask = 0x00;</span><br><span style="color: hsl(0, 100%, 40%);">- uint32_t sched_fn;</span><br><span style="color: hsl(0, 100%, 40%);">- uint8_t tn;</span><br><span style="color: hsl(120, 100%, 40%);">+ unsigned int tn;</span><br><span> </span><br><span> /* send time indication */</span><br><span> l1if_mph_time_ind(bts, fn);</span><br><span> </span><br><span style="color: hsl(0, 100%, 40%);">- /* process every TRX */</span><br><span style="color: hsl(120, 100%, 40%);">+ /* Initialize Downlink burst buffers */</span><br><span style="color: hsl(120, 100%, 40%);">+ bts_sched_init_buffers(bts, fn);</span><br><span style="color: hsl(120, 100%, 40%);">+</span><br><span style="color: hsl(120, 100%, 40%);">+ /* Populate Downlink burst buffers for each TRX/TS */</span><br><span> llist_for_each_entry(trx, &bts->trx_list, list) {</span><br><span> const struct phy_link *plink = trx->pinst->phy_link;</span><br><span> struct trx_l1h *l1h = trx->pinst->u.osmotrx.hdl;</span><br><span>@@ -113,66 +167,36 @@</span><br><span> if (!trx_if_powered(l1h))</span><br><span> continue;</span><br><span> </span><br><span style="color: hsl(0, 100%, 40%);">- /* advance frame number, so the transceiver has more</span><br><span style="color: hsl(0, 100%, 40%);">- * time until it must be transmitted. */</span><br><span style="color: hsl(0, 100%, 40%);">- sched_fn = GSM_TDMA_FN_SUM(fn, plink->u.osmotrx.clock_advance);</span><br><span style="color: hsl(0, 100%, 40%);">-</span><br><span> /* process every TS of TRX */</span><br><span> for (tn = 0; tn < ARRAY_SIZE(trx->ts); tn++) {</span><br><span style="color: hsl(0, 100%, 40%);">- const struct phy_instance *pinst = trx->pinst;</span><br><span style="color: hsl(0, 100%, 40%);">- struct l1sched_ts *l1ts = trx->ts[tn].priv;</span><br><span style="color: hsl(120, 100%, 40%);">+ struct phy_instance *pinst = trx->pinst;</span><br><span style="color: hsl(120, 100%, 40%);">+ struct gsm_bts_trx_ts *ts = &trx->ts[tn];</span><br><span style="color: hsl(120, 100%, 40%);">+ struct l1sched_ts *l1ts = ts->priv;</span><br><span style="color: hsl(120, 100%, 40%);">+ struct trx_dl_burst_req *br;</span><br><span> </span><br><span> /* ready-to-send */</span><br><span style="color: hsl(0, 100%, 40%);">- _sched_rts(l1ts, GSM_TDMA_FN_SUM(sched_fn, plink->u.osmotrx.rts_advance));</span><br><span style="color: hsl(120, 100%, 40%);">+ _sched_rts(l1ts, GSM_TDMA_FN_SUM(fn, plink->u.osmotrx.clock_advance</span><br><span style="color: hsl(120, 100%, 40%);">+ + plink->u.osmotrx.rts_advance));</span><br><span> </span><br><span style="color: hsl(0, 100%, 40%);">- /* All other parameters to be set by _sched_dl_burst() */</span><br><span style="color: hsl(0, 100%, 40%);">- br = (struct trx_dl_burst_req) {</span><br><span style="color: hsl(0, 100%, 40%);">- .fn = sched_fn,</span><br><span style="color: hsl(0, 100%, 40%);">- .tn = tn,</span><br><span style="color: hsl(0, 100%, 40%);">- };</span><br><span style="color: hsl(0, 100%, 40%);">-</span><br><span style="color: hsl(0, 100%, 40%);">- /* get burst for FN */</span><br><span style="color: hsl(0, 100%, 40%);">- _sched_dl_burst(l1ts, &br);</span><br><span style="color: hsl(0, 100%, 40%);">- if (br.burst_len == 0) {</span><br><span style="color: hsl(0, 100%, 40%);">- /* if no bits, send no burst */</span><br><span style="color: hsl(0, 100%, 40%);">- continue;</span><br><span style="color: hsl(0, 100%, 40%);">- }</span><br><span style="color: hsl(120, 100%, 40%);">+ /* pre-initialized buffer for the Downlink burst */</span><br><span style="color: hsl(120, 100%, 40%);">+ br = &pinst->u.osmotrx.br[tn];</span><br><span> </span><br><span> /* resolve PHY instance if freq. hopping is enabled */</span><br><span style="color: hsl(0, 100%, 40%);">- if (trx->ts[tn].hopping.enabled) {</span><br><span style="color: hsl(0, 100%, 40%);">- pinst = dlfh_route_br(&br, &trx->ts[tn]);</span><br><span style="color: hsl(120, 100%, 40%);">+ if (ts->hopping.enabled) {</span><br><span style="color: hsl(120, 100%, 40%);">+ pinst = dlfh_route_br(br, ts);</span><br><span> if (pinst == NULL)</span><br><span> continue;</span><br><span style="color: hsl(120, 100%, 40%);">+ /* simply use a different buffer */</span><br><span style="color: hsl(120, 100%, 40%);">+ br = &pinst->u.osmotrx.br[tn];</span><br><span> }</span><br><span> </span><br><span style="color: hsl(0, 100%, 40%);">- if (pinst->trx == bts->c0) {</span><br><span style="color: hsl(0, 100%, 40%);">- /* update dummy burst mask for C0 */</span><br><span style="color: hsl(0, 100%, 40%);">- c0_mask |= (1 << tn);</span><br><span style="color: hsl(0, 100%, 40%);">- /* ensure no attenuation on C0 */</span><br><span style="color: hsl(0, 100%, 40%);">- br.att = 0;</span><br><span style="color: hsl(0, 100%, 40%);">- }</span><br><span style="color: hsl(0, 100%, 40%);">-</span><br><span style="color: hsl(0, 100%, 40%);">- trx_if_send_burst(pinst->u.osmotrx.hdl, &br);</span><br><span style="color: hsl(120, 100%, 40%);">+ /* get burst for FN */</span><br><span style="color: hsl(120, 100%, 40%);">+ _sched_dl_burst(l1ts, br);</span><br><span> }</span><br><span> }</span><br><span> </span><br><span style="color: hsl(0, 100%, 40%);">- /* send dummy bursts on inactive timeslots of C0 */</span><br><span style="color: hsl(0, 100%, 40%);">- struct phy_instance *pinst = trx_phy_instance(bts->c0);</span><br><span style="color: hsl(0, 100%, 40%);">- struct trx_l1h *l1h = pinst->u.osmotrx.hdl;</span><br><span style="color: hsl(0, 100%, 40%);">- struct phy_link *plink = pinst->phy_link;</span><br><span style="color: hsl(0, 100%, 40%);">-</span><br><span style="color: hsl(0, 100%, 40%);">- br = (struct trx_dl_burst_req) {</span><br><span style="color: hsl(0, 100%, 40%);">- .fn = GSM_TDMA_FN_SUM(fn, plink->u.osmotrx.clock_advance),</span><br><span style="color: hsl(0, 100%, 40%);">- .burst_len = GSM_BURST_LEN,</span><br><span style="color: hsl(0, 100%, 40%);">- };</span><br><span style="color: hsl(0, 100%, 40%);">-</span><br><span style="color: hsl(0, 100%, 40%);">- memcpy(br.burst, _sched_dummy_burst, GSM_BURST_LEN);</span><br><span style="color: hsl(0, 100%, 40%);">-</span><br><span style="color: hsl(0, 100%, 40%);">- for (br.tn = 0; br.tn < TRX_NR_TS; br.tn++) {</span><br><span style="color: hsl(0, 100%, 40%);">- if (c0_mask & (1 << br.tn))</span><br><span style="color: hsl(0, 100%, 40%);">- continue;</span><br><span style="color: hsl(0, 100%, 40%);">- trx_if_send_burst(l1h, &br);</span><br><span style="color: hsl(0, 100%, 40%);">- }</span><br><span style="color: hsl(120, 100%, 40%);">+ /* Send everything to the PHY */</span><br><span style="color: hsl(120, 100%, 40%);">+ bts_sched_flush_buffers(bts);</span><br><span> }</span><br><span> </span><br><span> /* Find a route (TRX instance) for a given Uplink burst indication */</span><br><span></span><br></pre><p>To view, visit <a href="https://gerrit.osmocom.org/c/osmo-bts/+/24323">change 24323</a>. 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<div style="display:none"> Gerrit-Project: osmo-bts </div>
<div style="display:none"> Gerrit-Branch: master </div>
<div style="display:none"> Gerrit-Change-Id: Iec78989517865b3275a9784d1042a5ebd1d2815f </div>
<div style="display:none"> Gerrit-Change-Number: 24323 </div>
<div style="display:none"> Gerrit-PatchSet: 1 </div>
<div style="display:none"> Gerrit-Owner: fixeria <vyanitskiy@sysmocom.de> </div>
<div style="display:none"> Gerrit-MessageType: newchange </div>