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authorDaniel Willmann <dwillmann@sysmocom.de>2020-04-09 17:43:56 +0200
committerPau Espin Pedrol <pespin@sysmocom.de>2020-08-17 19:11:19 +0200
commit624b5cdc221ebb254b6091bacd4630b8a9339290 (patch)
tree9ea1c94465a80d4e0a454d552e9e6e1394803644 /doc/manuals
parentd6daf726a2176539b07a6bce41b91385f498f9e0 (diff)
osmo-bts-trx: Use much lower clock advance values towards PCU and TRX
osmotrx fn-advance (which is the clock_advance variable here) and osmotrx rts-advance together make up the minimum delay the BTS can react to a channel request, etc. The default of 20 are around 92ms which is clearly too much. With modern hardware and using SCHED_RR a lower value should not be an issue. See OS#4487 for some related measurements on more CPU-limited devices like a LimeNet-micro3. Fixes: OS#4487 Fixes: SYS#4885 Related: SYS#4881 Change-Id: I7da3d0948f38e12342fb714b29f8edc5e9d0933d
Diffstat (limited to 'doc/manuals')
-rw-r--r--doc/manuals/chapters/bts-models.adoc5
1 files changed, 2 insertions, 3 deletions
diff --git a/doc/manuals/chapters/bts-models.adoc b/doc/manuals/chapters/bts-models.adoc
index 495571fa..5cb04616 100644
--- a/doc/manuals/chapters/bts-models.adoc
+++ b/doc/manuals/chapters/bts-models.adoc
@@ -270,8 +270,7 @@ on a remote host will inevitably require a higher fn-advance than
running it on the same machine, where the UDP packets are just passed
over the loopback device.
-The default value for `fn-advance` is 20 (corresponding to 92
-milliseconds).
+The default value for `fn-advance` is 2 (corresponding to 9.2 milliseconds).
===== `osmotrx rts-advance <0-30>`
@@ -290,7 +289,7 @@ reported on L1SAP to higher layers will be computed as follows:
N + fn-advance + rts-advance
-The default value of `rts-advance` is 5 (corresponding to 23 milliseconds).
+The default value of `rts-advance` is 3 (corresponding to 14 milliseconds).
Do not change this unless you have a good reason!
===== `osmotrx rx-gain <0-50>`