Commit Graph

4 Commits

Author SHA1 Message Date
Harald Welte 6c8ca97546 Support building with -Werror=strict-prototypes / -Werror=old-style-definition
Unfortunately "-std=c99" is not sufficient to make gcc ignore cold that
uses constructs of earlier C standards, which were abandoned in C99.

See https://lwn.net/ml/fedora-devel/Y1kvF35WozzGBpc8@redhat.com/ for
some related discussion.

Change-Id: Ic92aa70d569778a776f4c5d24c455f71fd50b61b
2022-11-10 00:28:46 +00:00
Neels Hofmeyr c1bfc88b6b fix performance for chan_counts and all_allocated stats
The all_allocated_update_bsc() does inefficient iterating to count
active/inactive lchans, which scales badly for high numbers of TRX
managed by osmo-bsc.

We need to update the all_allocated flags immediately (periodic counting
alone would suffer from undersampling), so, until now, we are calling
this inefficient function every time a channel state changes.

Instead of iterating all channels for any chan state changes anywhere,
keep global state of the current channel counts, and on channel state
change only update those ts, trx, bts counts that actually change.

A desirable side effect: for connection stats and handover decision 2,
we can now also use the globally updated channel counts and save a bunch
of inefficient iterations.

To get accurate channel counts at all times, spread around some
chan_counts_ts_update() calls in pivotal places. It re-counts the given
timeslot and cascades counter changes, iff required.

Just in case I missed some channel accounting, still run an inefficient
iterating count regularly that detects errors, logs them and fixes them.
No real harm done if such error appears. None show in ttcn3 BSC_Tests.
It is fine to do the inefficient iteration once per second; channel
state changes can realistically happen hundreds of times per second.

Related: SYS#5976
Change-Id: I580bfae329aac8d4552723164741536af6512011
2022-06-02 14:24:30 +02:00
Neels Hofmeyr f8345b7ad5 fix two comments in chan_counts.h
An earlier patch version had that typedef, the merged version switched
to the struct containing the array.

Change-Id: Id8ca7b298436feb98f4a563ad3cdea510b9362b0
2022-01-21 16:53:35 +01:00
Neels Hofmeyr e455f0ab02 refactor lchan counting
Add chan_counts_for_trx() and chan_counts_for_bts(). Drop
bts_count_free_ts() and trx_count_free_ts().

Rationale:

The bts_count_free_ts() and trx_count_free_ts() always returned the
number of free lchans, not timeslots. Hence, passing the pchan type as
argument never really matched the semantics.

Especially, when looking for free SDCCH, there is no clear match on a
gsm_phys_chan_config enum value: SDCCH8_SACCH8C, CCCH_SDCCH4,
CCCH_SDCCH4_CBCH, SDCCH8_SACCH8C_CBCH? -- GSM_LCHAN_SDCCH is clear.

==> Rather count free lchans by enum gsm_chan_t.

Counting lchans of distinct types required separate iterations for each
lchan type.

==> Rather compose an array of counts for all types, in one go.

I need to count the amount of free SDCCH lchans in an upcoming patch to
implement the performance indicator allAvailableAllocatedSDCCH (cumulate
time for which no SDCCH are available).

To implement allAvailableAllocated{SDCCH,TCH}, I need a count of both
the used as well as the total lchans for a type: it does not make sense
to flag "all available allocated" if none are ever available.

To properly count dynamic ts, I need the maximum total that can be
possible at any time. And to count currently free lchans, I need the
current total. This may seem counter intuitive, but consider, e.g.:

- Obviously, if a cell has only static TCH/F timeslots, it does not make
  sense to flag that all available TCH/H are occupied, because no TCH/H
  are available ever. Just stating this as contrast to dyn TS.

- If a cell has OSMO_DYN timeslots, I *do* want to flag that all TCH/H
  are occupied when all dyn timeslots are fully occupied.

- If those OSMO_DYN however are all used as TCH/F, the current total of
  TCH/H becomes zero, and it seems like TCH/H should not be considered.

- To count the nr of currently free lchans, I need the currently
  possible total of lchans and the nr of occupied lchans.

So return both a maximum total and a current total of lchans. In above
example, the maximum total shows that there would be TCH/H possible.

BTW, it would be nice to keep a chan_counts array on trx, bts and bsc
level and update as channels are allocated and released, instead of
counting them all over periodically. But it's less error prone this way.

Related: SYS#4878
Change-Id: I2fb48c549186db812b1e9d6b735a92e80f27b8d3
2021-11-10 13:27:43 +00:00