Attention is currently required from: fixeria, laforge.

Hello Jenkins Builder, laforge,

I'd like you to reexamine a change. Please visit

https://gerrit.osmocom.org/c/erlang/osmo-s1gw/+/39666?usp=email

to look at the new patch set (#4).

Change subject: s1gw_metrics: add histograms for gen_sctp:send/3 delay ......................................................................

s1gw_metrics: add histograms for gen_sctp:send/3 delay

https://www.erlang.org/doc/apps/kernel/gen_sctp.html#send/3 clearly states that gen_sctp:send/3 is blocking, unless non_block_send is set.

With the current architecture of the S1GW, gen_sctp:send/3 may block the S1GW-MME link (sctp_client) or the eNB-S1GW link (sctp_server) completely, preventing sending and receiving of other S1AP PDUs.

Ideally, we should rework the S1GW to spawn a separate process for each received S1AP PDU, so that blocking gen_sctp:send/3 would at least not block receiving and processing of incoming PDUs. But this would require quite some effort.

For now, let's add a histogram reflecting min/max/avg/mean/median delay caused by gen_sctp:send/3, so that we can detect this when the problem starts biting us.

Change-Id: I7633a6e6182bda3fca4e7562e2b780b2b9f9708f Related: SYS#7288 --- M config/sys.config M include/s1gw_metrics.hrl M src/s1gw_metrics.erl M src/sctp_common.erl M src/sctp_proxy.erl M src/sctp_server.erl 6 files changed, 54 insertions(+), 7 deletions(-)

git pull ssh://gerrit.osmocom.org:29418/erlang/osmo-s1gw refs/changes/66/39666/4