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pespin gerrit-no-reply at lists.osmocom.orgpespin has submitted this change. ( https://gerrit.osmocom.org/c/osmo-bts/+/17766 ) Change subject: osmo-bts-trx: Use much lower clock advance values towards PCU and TRX ...................................................................... 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 --- M doc/manuals/chapters/bts-models.adoc M src/osmo-bts-trx/main.c 2 files changed, 4 insertions(+), 5 deletions(-) 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 diff --git a/doc/manuals/chapters/bts-models.adoc b/doc/manuals/chapters/bts-models.adoc index 495571f..5cb0461 100644 --- a/doc/manuals/chapters/bts-models.adoc +++ b/doc/manuals/chapters/bts-models.adoc @@ -270,8 +270,7 @@ 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 @@ 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>` diff --git a/src/osmo-bts-trx/main.c b/src/osmo-bts-trx/main.c index 33bc6f2..166af7e 100644 --- a/src/osmo-bts-trx/main.c +++ b/src/osmo-bts-trx/main.c @@ -167,8 +167,8 @@ plink->u.osmotrx.remote_ip = talloc_strdup(plink, "127.0.0.1"); plink->u.osmotrx.base_port_local = 5800; plink->u.osmotrx.base_port_remote = 5700; - plink->u.osmotrx.clock_advance = 20; - plink->u.osmotrx.rts_advance = 5; + plink->u.osmotrx.clock_advance = 2; + plink->u.osmotrx.rts_advance = 3; /* attempt use newest TRXD version by default: */ plink->u.osmotrx.trxd_hdr_ver_max = TRX_DATA_FORMAT_VER; } -- To view, visit https://gerrit.osmocom.org/c/osmo-bts/+/17766 To unsubscribe, or for help writing mail filters, visit https://gerrit.osmocom.org/settings Gerrit-Project: osmo-bts Gerrit-Branch: master Gerrit-Change-Id: I7da3d0948f38e12342fb714b29f8edc5e9d0933d Gerrit-Change-Number: 17766 Gerrit-PatchSet: 5 Gerrit-Owner: daniel <dwillmann at sysmocom.de> Gerrit-Reviewer: Jenkins Builder Gerrit-Reviewer: daniel <dwillmann at sysmocom.de> Gerrit-Reviewer: dexter <pmaier at sysmocom.de> Gerrit-Reviewer: fixeria <vyanitskiy at sysmocom.de> Gerrit-Reviewer: laforge <laforge at osmocom.org> Gerrit-Reviewer: neels <nhofmeyr at sysmocom.de> Gerrit-Reviewer: pespin <pespin at sysmocom.de> Gerrit-MessageType: merged -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.osmocom.org/pipermail/gerrit-log/attachments/20200818/2e3ad3ba/attachment.htm>