exceeding match limit on watchers

[Ivan Mikhaylov]

Hello everyone!

Our VESNIN server has a lot of temperature sensors on it, so we tried to attach
watchers via yaml for them. The sd_bus_add_match() returns -105 (ENOBUFS) which
represents exceeding 'some limit', according to the the doc. First of all we
tried to figure out why it didn't work, and found that match() from sdbusplus
didn't raise any exception/warning/log, etc. in the event of errors, and just
passed through silently. I've created an issue for it:
https://github.com/openbmc/sdbusplus/issues/38 .

In manpage for sd_bus_add_match() there is no helpful information about
possible reasons for this over the limit case. I'm trying to figure it out from
systemd code, with little success so far.

SD_BUS_ERROR_LIMITS_EXCEEDED
  Some limited resource has been exhausted.

Maybe anybody knows what and where the limit is and where we can tweak it?
As far as I can see, there are only ulimit settings In systemd's system.conf.

Thanks.