<p>pespin <strong>submitted</strong> this change.</p><p><a href="https://gerrit.osmocom.org/c/osmo-bts/+/17766">View Change</a></p><div style="white-space:pre-wrap">Approvals:
Jenkins Builder: Verified
fixeria: Looks good to me, but someone else must approve
daniel: Looks good to me, but someone else must approve
pespin: Looks good to me, approved
</div><pre style="font-family: monospace,monospace; white-space: pre-wrap;">osmo-bts-trx: Use much lower clock advance values towards PCU and TRX<br><br>osmotrx fn-advance (which is the clock_advance variable here) and<br>osmotrx rts-advance together make up the minimum delay the BTS can react<br>to a channel request, etc.<br><br>The default of 20 are around 92ms which is clearly too much. With<br>modern hardware and using SCHED_RR a lower value should not be an issue.<br><br>See OS#4487 for some related measurements on more CPU-limited devices like a<br>LimeNet-micro3.<br><br>Fixes: OS#4487<br>Fixes: SYS#4885<br>Related: SYS#4881<br>Change-Id: I7da3d0948f38e12342fb714b29f8edc5e9d0933d<br>---<br>M doc/manuals/chapters/bts-models.adoc<br>M src/osmo-bts-trx/main.c<br>2 files changed, 4 insertions(+), 5 deletions(-)<br><br></pre><pre style="font-family: monospace,monospace; white-space: pre-wrap;"><span>diff --git a/doc/manuals/chapters/bts-models.adoc b/doc/manuals/chapters/bts-models.adoc</span><br><span>index 495571f..5cb0461 100644</span><br><span>--- a/doc/manuals/chapters/bts-models.adoc</span><br><span>+++ b/doc/manuals/chapters/bts-models.adoc</span><br><span>@@ -270,8 +270,7 @@</span><br><span> running it on the same machine, where the UDP packets are just passed</span><br><span> over the loopback device.</span><br><span> </span><br><span style="color: hsl(0, 100%, 40%);">-The default value for `fn-advance` is 20 (corresponding to 92</span><br><span style="color: hsl(0, 100%, 40%);">-milliseconds).</span><br><span style="color: hsl(120, 100%, 40%);">+The default value for `fn-advance` is 2 (corresponding to 9.2 milliseconds).</span><br><span> </span><br><span> ===== `osmotrx rts-advance <0-30>`</span><br><span> </span><br><span>@@ -290,7 +289,7 @@</span><br><span> </span><br><span> N + fn-advance + rts-advance</span><br><span> </span><br><span style="color: hsl(0, 100%, 40%);">-The default value of `rts-advance` is 5 (corresponding to 23 milliseconds).</span><br><span style="color: hsl(120, 100%, 40%);">+The default value of `rts-advance` is 3 (corresponding to 14 milliseconds).</span><br><span> Do not change this unless you have a good reason!</span><br><span> </span><br><span> ===== `osmotrx rx-gain <0-50>`</span><br><span>diff --git a/src/osmo-bts-trx/main.c b/src/osmo-bts-trx/main.c</span><br><span>index 33bc6f2..166af7e 100644</span><br><span>--- a/src/osmo-bts-trx/main.c</span><br><span>+++ b/src/osmo-bts-trx/main.c</span><br><span>@@ -167,8 +167,8 @@</span><br><span> plink->u.osmotrx.remote_ip = talloc_strdup(plink, "127.0.0.1");</span><br><span> plink->u.osmotrx.base_port_local = 5800;</span><br><span> plink->u.osmotrx.base_port_remote = 5700;</span><br><span style="color: hsl(0, 100%, 40%);">- plink->u.osmotrx.clock_advance = 20;</span><br><span style="color: hsl(0, 100%, 40%);">- plink->u.osmotrx.rts_advance = 5;</span><br><span style="color: hsl(120, 100%, 40%);">+ plink->u.osmotrx.clock_advance = 2;</span><br><span style="color: hsl(120, 100%, 40%);">+ plink->u.osmotrx.rts_advance = 3;</span><br><span> /* attempt use newest TRXD version by default: */</span><br><span> plink->u.osmotrx.trxd_hdr_ver_max = TRX_DATA_FORMAT_VER;</span><br><span> }</span><br><span></span><br></pre><p>To view, visit <a href="https://gerrit.osmocom.org/c/osmo-bts/+/17766">change 17766</a>. To unsubscribe, or for help writing mail filters, visit <a href="https://gerrit.osmocom.org/settings">settings</a>.</p><div itemscope itemtype="http://schema.org/EmailMessage"><div itemscope itemprop="action" itemtype="http://schema.org/ViewAction"><link itemprop="url" href="https://gerrit.osmocom.org/c/osmo-bts/+/17766"/><meta itemprop="name" content="View Change"/></div></div>
<div style="display:none"> Gerrit-Project: osmo-bts </div>
<div style="display:none"> Gerrit-Branch: master </div>
<div style="display:none"> Gerrit-Change-Id: I7da3d0948f38e12342fb714b29f8edc5e9d0933d </div>
<div style="display:none"> Gerrit-Change-Number: 17766 </div>
<div style="display:none"> Gerrit-PatchSet: 5 </div>
<div style="display:none"> Gerrit-Owner: daniel <dwillmann@sysmocom.de> </div>
<div style="display:none"> Gerrit-Reviewer: Jenkins Builder </div>
<div style="display:none"> Gerrit-Reviewer: daniel <dwillmann@sysmocom.de> </div>
<div style="display:none"> Gerrit-Reviewer: dexter <pmaier@sysmocom.de> </div>
<div style="display:none"> Gerrit-Reviewer: fixeria <vyanitskiy@sysmocom.de> </div>
<div style="display:none"> Gerrit-Reviewer: laforge <laforge@osmocom.org> </div>
<div style="display:none"> Gerrit-Reviewer: neels <nhofmeyr@sysmocom.de> </div>
<div style="display:none"> Gerrit-Reviewer: pespin <pespin@sysmocom.de> </div>
<div style="display:none"> Gerrit-MessageType: merged </div>