Move timeslot applicability check outside of nested for loop into
separate functions and document them. Add corresponding tests.
This allows us to clarify types used in TS-related computations.
Change-Id: Ic39e848da47dc11357782362fdf6206d2c1457c2
Related: OS#2282
Don't use PDCH from free TFI lookup routine. This allows for simpler
function which can be moved to mslot_class.c alongside with other
similar helpers.
Change-Id: Ie154866900453d232a890f7b9a30911b451525a1
Related: OS#2282
The PDCH class and corresponding functions are rather self-contained and
independent from BTS implementation. Let's move them into separate file
to make bts.cpp more manageable. As additional benefit it allow us to
somewhat untangle all the different cross-dependent includes.
Change-Id: Ie05e25361e6741a81b024679f9675c98d4923683
Related: OS#1539
* move USF allocation into separate function
* document USF allocation
This allows to clearly see where selected UL TS is forced into single TS
in algorithm B allocator.
Change-Id: I563dc10827ce68295553f88f3bf2e1fc0ba595c1
Related: OS#2282
* generalize TS allocation and move it into separate function
* move single-slot allocation into separate function
* use common functions for TS allocation on both UL and DL
Change-Id: Ied45ae380c345bc76fe9d6fd9a6184d1109f83f2
Related: OS#2282
Move computation of RX mask into separate function and document it. This
allows to significantly shrink find_multi_slot() function and overall
improve code readability.
Since the test output requires cosmetic adjustment anyway due to change
in the sequence of log messages, use this opportunity to better group
and format log message.
Change-Id: I731726a096bba7ee97499e5cbe3e7401869d7392
Related: OS#2282
Many files include unnecessary headers and don't include headers which
are actually used. Because of that combined with the fact that OsmoPCU
is a mixture of C and C++, it makes it hard to modularize code. Fix
this (using iwyu [1] tool):
* add missing headers
* remove unused headers
[1] https://include-what-you-use.org/
Related: OS#1539
Change-Id: I8c9f488a43b099c72b2d30d3245e7ba50872fc00
Move TRX check inside local tfi_find_free() wrapper to make main
algorithm easier to follow.
Change-Id: I02da2b8ba8c9c8815dae0e39e1fed277ca0df171
Related: OS#2282
* document used parameters and return values
* use consistent formatting
* constify function parameters where appropriate (adjusting parameter
types if necessary)
Change-Id: I211b10b4da59c73d509b719346774515c761886a
Related: OS#2282
* define and use constant for occupied TFI instead copying the same
magic number all over the place
* use libosmocore's define for bit pretty-printer
Change-Id: I2699ceebf0cbec01652a02fa68ccc9e9419d0293
Related: OS#2282
Assign reserved_*_slots only when multislot masks are found to avoid
reassignment and make code easier to follow.
Change-Id: I9b0482f4ea75ead9855cd78e33c8e70d0ccf4484
Related: OS#2282
* drop unused parameters (from both functions and structs)
* document used parameters and return values
* tighten types used for parameters
* use consistent formatting
Tests are adjusted accordingly but test results are left untouched to
avoid regressions.
Change-Id: I39d81ab64ff790b9c4c2d0312a574485cd83e755
Related: OS#2282
The table B.1 is copy-pasted from 3GPP TS 45.002 and reformatted via
Emacs macros into C struct to avoid typos. The test output expanded
accordingly.
The allocation test expectations and output are adjusted accordingly.
Note: classes 35-45 which need TA offset are not properly supported
yet. This can be extended once we have such devices available for tests.
Change-Id: I1ef2eb99c517f25e7d1e71b985a3e0eb3879eb2c
Related: OS#2282
To facilitate testing and addition of support for new multislot classes,
hide multislot class struct internals:
* introduce mslot_class_get_*() functions
* use those functions instead of direct access to array of structs
* use ms_class as a parameter to find_multi_slot() instead of entire
object
Change-Id: Id796bcff1322b1e273a0e3236c66c23b9da8fac6
Add header similar to the one used in the standard, reformat to
facilitate further extention.
Change-Id: I786df6b154c0668d2cefa0ea84d7dea336b0da1d
Related: OS#2282
These functions are currently defined in src/gprs_rlcmac_ts_alloc.cpp
but will be needed elsewhere.
Turn them into template functions to support different types and move
them to pcu_utils.h.
Sponsored-by: On-Waves ehf
Currently casts from gprs_rlcmac_tbf to gprs_rlcmac_ul_tbf and
gprs_rlcmac_dl_tbf are done by using static_cast. This doesn't provide
protection against converting a gprs_rlcmac_ul_tbf pointer to a
gprs_rlcmac_dl_tbf pointer and vice versa.
This commit provides two functions as_ul_tbf and as_dl_tbf, that
behave similar like dynamic_cast but use the direction field instead
of RTTI.
Sponsored-by: On-Waves ehf
Currently the values Bmax/R default MS are computed under the
assumption than min(4, N_PDCH) DL slots are allocated for an MS, even
if multislot assignment is not enabled.
This commit changes the computation to assume 1 DL slot if algorithm
A is selected or the dynamic algorithm is used and has disabled
multislot assigment due to high load.
Sponsored-by: On-Waves ehf
Currently there is no persistent state being used in
alloc_algorithm_dynamic. So algorithm B is even used in persistent
high usage scenarios. If there are many active TBFs, multislot
assigments are not fair, because MS of a "higher" multislot class get
higher troughputs. On the other hand, as long as all PDCH are busy no
bandwidth will be wasted even if all MS use algorithm A.
This commit modifies alloc_algorithm_dynamic to disable algorithm B
when that call fails. It then keeps it disabled until there is a
single PDCH which is idle (it is considered idle, if there is at most
one active DL TBF assigned to it).
Sponsored-by: On-Waves ehf
Currently algorithm A can select an TBF even when there is no free
TBF in the reverse direction. While this does not necessarily lead to
an allocation failure, the probabily is higher. In addition, the
current slot reservations are not taken into account.
This commit changes the selection algorithm to prefer slots where TFI
are available in both directions and which are less reserved.
Sponsored-by: On-Waves ehf
Currently each tx_window combination is checked only once by using a
set containing the sets of TX slots that have been checked already.
This approach does not ensure, that num_tx and ul_ts really match the
tx_window being tested. This does not make a difference with the
current test cases probably because num_tx starts with 1 and is
increased each iteration. Since the bitmap optimization is equivalent
to a cache optimization strategy that only uses tx_window as key. On
the other hand, ul_ts, num_tx, and rx_mask cannot be derived from
tx_window, but these values are also refered to after the call to
test_and_set_bit(). This makes it difficult to prove that correctness
of the caching. While this will not lead to a defect, the results
might be less optimal.
This commit changes the optimization strategy to skip all tx_window
where ul_ts and ul_ts+num_tx-1 are not both contained. This provides
a similar degree of optimization like the set approach (only the
iteration with num_ts == 8 is not optimized, which only applies to to
ms class 18 and 29 MS) but ensures that the values of the related
variables have a clear relationship.
Note that the bitset based optimization for rx_window does not suffer
from a possible cache inconsistency, since only tx_window and
rx_window (tx_slot_count and rx_slot_count can be derived from the
windows and thus are covered by the cache key) are used after the call
to test_and_set_bit(). tx_window is constant over the whole lifetime
of the cache.
Sponsored-by: On-Waves ehf
The idea behind this meta algorithm is to automatically select one of
the other algorithms based on the system state. Basically algorithm B
will be selected if the PDCH usage is low to improve throughput and
latency. Algorithm A will be selected to support more concurrent MS.
This commit adds a first simple state-less version of this algorithm
that always tries B first and only if that fails A is tried
afterwards.
The following VTY command is added to the 'pcu' node:
- alloc-algorithm dynamic
Ticket: #1934
Sponsored-by: On-Waves ehf
This part of algorithm_b has already been disabled. Further work may
depend on this, but it is going out of sync. So this commit removes
it completely.
Sponsored-by: On-Waves ehf
Currently these algorithms modify other objects (MS, TBF, PDCH) even
if the allocation will fail later on. To implement an algorithm that
dynamically tries another algorithm on failure (e.g. A after B), the
first (failing) algorithm should not change or damage anything.
This commit refactors algorithm A and B to delay the actual allocation
until it is known that the allocation will not fail.
Ticket: #1934
Sponsored-by: On-Waves ehf
Currently this code path is only used, if an allocation has been
taken place in a former call to an allocation algorithm function.
If this was for an DL TBF, the first common TS was selected,
otherwise the least used common TS was selected for an UL TBF.
The shrinking of the UL set (to 1<<first_common_ts) is done in the
latter case.
This commit removes an additional code path that aligns the UL set to
first_common_ts, because it has no more influence on the set of
common TS after both UL and DL TBF have been allocated.
Sponsored-by: On-Waves ehf
Currently the TBFs are registered in a TFI indexed array within the TRX
objects. TBFs can be searched globally by TFI and TRX number. This
conflicts with the use of the same TFI for different TBF on different
PDCH. This use case requires the specification of the PDCH as
additional search dimension.
This commit moves the TFI index TBF arrays into the PDCH objects. The
related methods are updated accordingly.
Ticket: #1793
Sponsored-by: On-Waves ehf
Currently the TFI are managed per TRX, thus only a maximum of 32 TBF
per direction and per TRX are possible simultaneously.
This commit modifies algorithm_a() to allow the sharing of TFI
between different PDCH. Since algorithm A only assigns a single slot
to each TBF, the TFI of each PDCH can be assigned independently.
This increases the maximum to 32 TBF per direction and per PDCH
concerning the TFI allocation.
Ticket: #1793
Sponsored-by: On-Waves ehf
Currently the TFI and the TRX have to be determined before the actual TBF
allocation function is called, passing TFI and TRX number as
parameters. This does fit to TFI reuse for different slots, since
this were tightly coupled with the slot selection.
This commit just moves the TFI selection into the alloc_algorithm
functions. The tfi parameter is removed from the the TFI alloc
functions. The trx parameter is changed into use_trx to optionally
limit the trx selection (same semantics like in tfi_find_free).
Sponsored-by: On-Waves ehf
Currently the handling of MS_B and MS_C is not compliant with TS
45.002, annex B.1. These values may only interpreted as 0, if
frequency hopping is not enabled and if there is no change from Rx to
Tx or vice-versa.
This commit sets Ttb/Trb to 1 if the table entry is MS_B/MS_C, since
only combined down/up access modes are supported.
Sponsored-by: On-Waves ehf
Currently the masks are computed equally for each class type. This
does not make much sense for class type 2 MS, since those are capable
to work in full duplex mode.
This commit sets the masks to 0xff for class type 2 MS.
Sponsored-by: On-Waves ehf
According to TS 45.002, 6.4.2.2 the choice whether Tta or Tra has to
be applied, depends on the medium access mode (currently always
dynamic) and the number of UL/DL slots. Currently either value can be
used which might result in combinations not covered by the spec.
This commit changes find_multi_slots() to skip non-compliant
combinations.
Note that this code will have to be extended, if other medium
access modes are implemented.
Sponsored-by: On-Waves ehf
The local enums MASK_TT and MASK_TR replace the hard coded indices.
The variable m_idx is renamed to mask_sel for more clarity.
Sponsored-by: On-Waves ehf
Both functions only differ in the computation of the value for
num_tbfs.
This commit merge both functions and adds a parameter containing a
function for that compuation.
Sponsored-by: On-Waves ehf
Currently the slot selection of algorithm A is based on the current
slot usage by active TBF. Especially in the Dl after UL case which
reflects the commen use case "MS initiates TCP connection", the
resulting distribution is not optimal with respect to PDCH usage.
This commit changes the implementation to use the slot reservation
information instead.
Sponsored-by: On-Waves ehf
The current logging statements within the inner loop of
find_multi_slots drain quite a lot of CPU resources even if
LOGL_DEBUG is not enabled. This might cause issues on the target
hardware.
This commit disables these LOGP calls unless the
ENABLE_TS_ALLOC_DEBUG macro has been set explicitly. This results in
a reduction in the CPU usage reported by callgrind for
find_multi_slots from 42% to 25% when executing AllocTest.
Sponsored-by: On-Waves ehf
According to callgrind, this function consumes 33% CPU when running
the AllocTest program.
This commit uses the assigned_usf() method to get the USFs allocated
by a PDCH instead of traversing the TBFs.
Sponsored-by: On-Waves ehf
Currently the search of the "best" slot combination is done
separately from the UL slot selection, which can lead to an
allocation failure due to USF exhaustion even if another combination
had been possible.
This commit reduces the probability for this event by skipping UL
slots without free USF while calculation the capacity.
Note that the implementation is rather inefficient which will be
fixed by the following commits.
Sponsored-by: On-Waves ehf
Since currently the algorithm B will only allocate a single UL slot
and will have to stick to it (first common TS), the other possible UL
slots will not be allocated while the reservation is kept.
This commit adds code to update the reserved set of UL slots to only
reserve the single common TS when the UL TBF is allocated.
Interestingly this leads to fewer allocated TBF in some cases due to
USF exhaustion. This will be improved by the following commit "alloc:
Skip common TS without free USF".
Sponsored-by: On-Waves ehf
Currently the capacity of a PDCH slot is calculated as 32 - N_reserved
for each direction. This can result in a capacity of 0 and even
negative values.
This commit forces the capacity of an usable slot to be at least zero
under the assumption, that an overly reserved PDCH is still better
than none.
Sponsored-by: On-Waves ehf
Currently al possible UL slots are included in the capacity
calculation which is the base of the slot selection. Nevertheless
UL-only slots will never be used, since only one uplink slot (which
must be a common slot) will be used.
This patch changes the code to only include common slots in the
capacity sum.
Note that this might not be optimal if algorithm B supported
multiple uplink slots.
Sponsored-by: On-Waves ehf
The current implementation always starts the downlink slot allocation
with the first possible slot, depending on which channels are enabled
and which multislot class is offered by the MS. So in configurations
with many (>4) PDCH, some PDCH are not really used.
The new implementation introduced by this commit differs as follows:
- The reservation mechanism provided by GprsMs is used to avoid
incompatibilities is used in the same way like algo A does. This
basically means, that the allocation is done once when the first
TBF is requested and then used until all TBF have been released.
- All combinations of Rx and Tx slots are checked for compatibility
with the multiscot class. Basically the combination with the most
usable PDCH and the least number of reservations is used.
- Only one UL slots is provided.
- Tta and Tra are checked.
Sponsored-by: On-Waves ehf
Currently algorithm A bases its time slots selection on the number of
TBF actively using the PDCHs. This statistically prefers the first
time slots, especially with short living TBFs. So when the first TBF
is triggered by an uplink transfer (which generally results in a
short-lived TBF) the potentially longer living DL TBF will be bound
to the same slot. When another MS then requests an uplink TBF, it
will get the same slot (no UL TBF currently active).
This commit changes the algorithm to base its selection on reserved
slots instead.
Sponsored-by: On-Waves ehf
According to TS 45.002, 6.4.2 the training sequence (TSC) must be the
same for all slots in a multi-slot set.
This commit updates find_possible_pdchs() to only consider slots with
the same TSC if more that 1 slot shall be assigned.
Note that the first PDCH's TSC will be used as reference, so if two
or more groups with a common TSC are configured, only the first will
be used. This restriction does not apply to algorithm A, since it
will not assign more than one slot and therefore sets the max_slots
parameter to 1.
Sponsored-by: On-Waves ehf
Currently only the first enabled PDCH will be used. Beside the
throughput this will also limit the number of TBFs:
- number of UL TBFs <= 7
- number of DL TBFs <= 32
This commit changes the allocation algorithm to use the PDCH with the
least number of attached TBFs. This will improve the troughput in
both directions and the UL limits:
- number of UL TBFs <= min(32, N_PDCH * 7) UL TBFs
Ticket: #1794
Sponsored-by: On-Waves ehf
Max