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diff --git a/docs/ietf/draft-ietf-bmwg-mlrsearch-02.md b/docs/ietf/draft-ietf-bmwg-mlrsearch-02.md new file mode 100644 index 0000000000..48db64e46a --- /dev/null +++ b/docs/ietf/draft-ietf-bmwg-mlrsearch-02.md @@ -0,0 +1,682 @@ +--- +title: Multiple Loss Ratio Search for Packet Throughput (MLRsearch) +abbrev: Multiple Loss Ratio Search +docname: draft-ietf-bmwg-mlrsearch-02 +date: 2021-11-02 + +ipr: trust200902 +area: ops +wg: Benchmarking Working Group +kw: Internet-Draft +cat: info + +coding: us-ascii +pi: # can use array (if all yes) or hash here + toc: yes + sortrefs: # defaults to yes + symrefs: yes + +author: + - + ins: M. Konstantynowicz + name: Maciek Konstantynowicz + org: Cisco Systems + role: editor + email: mkonstan@cisco.com + - + ins: V. Polak + name: Vratko Polak + org: Cisco Systems + email: vrpolak@cisco.com + +normative: + RFC2544: + +informative: + FDio-CSIT-MLRsearch: + target: https://docs.fd.io/csit/rls2101/report/introduction/methodology_data_plane_throughput/methodology_mlrsearch_tests.html + title: "FD.io CSIT Test Methodology - MLRsearch" + date: 2021-02 + PyPI-MLRsearch: + target: https://pypi.org/project/MLRsearch/0.4.0/ + title: "MLRsearch 0.4.0, Python Package Index" + date: 2021-04 + +--- abstract + +This document proposes changes to [RFC2544], specifically to packet +throughput search methodology, by defining a new search algorithm +referred to as Multiple Loss Ratio search (MLRsearch for short). Instead +of relying on binary search with pre-set starting offered load, it +proposes a novel approach discovering the starting point in the initial +phase, and then searching for packet throughput based on defined packet +loss ratio (PLR) input criteria and defined final trial duration time. +One of the key design principles behind MLRsearch is minimizing the +total test duration and searching for multiple packet throughput rates +(each with a corresponding PLR) concurrently, instead of doing it +sequentially. + +The main motivation behind MLRsearch is the new set of challenges and +requirements posed by NFV (Network Function Virtualization), +specifically software based implementations of NFV data planes. Using +[RFC2544] in the experience of the authors yields often not repetitive +and not replicable end results due to a large number of factors that are +out of scope for this draft. MLRsearch aims to address this challenge +in a simple way of getting the same result sooner, so more repetitions +can be done to describe the replicability. + +--- middle + +# Terminology + +* Frame size: size of an Ethernet Layer-2 frame on the wire, including + any VLAN tags (dot1q, dot1ad) and Ethernet FCS, but excluding Ethernet + preamble and inter-frame gap. Measured in bytes (octets). +* Packet size: same as frame size, both terms used interchangeably. +* Device Under Test (DUT): In software networking, "device" denotes a + specific piece of software tasked with packet processing. Such device + is surrounded with other software components (such as operating system + kernel). It is not possible to run devices without also running the + other components, and hardware resources are shared between both. For + purposes of testing, the whole set of hardware and software components + is called "system under test" (SUT). As SUT is the part of the whole + test setup performance of which can be measured by [RFC2544] methods, + this document uses SUT instead of [RFC2544] DUT. Device under test + (DUT) can be re-introduced when analysing test results using whitebox + techniques, but this document sticks to blackbox testing. +* System Under Test (SUT): System under test (SUT) is a part of the + whole test setup whose performance is to be benchmarked. The complete + test setup contains other parts, whose performance is either already + established, or not affecting the benchmarking result. +* Bi-directional throughput tests: involve packets/frames flowing in + both transmit and receive directions over every tested interface of + SUT/DUT. Packet flow metrics are measured per direction, and can be + reported as aggregate for both directions and/or separately + for each measured direction. In most cases bi-directional tests + use the same (symmetric) load in both directions. +* Uni-directional throughput tests: involve packets/frames flowing in + only one direction, i.e. either transmit or receive direction, over + every tested interface of SUT/DUT. Packet flow metrics are measured + and are reported for measured direction. +* Packet Loss Ratio (PLR): ratio of packets received relative to packets + transmitted over the test trial duration, calculated using formula: + PLR = ( pkts_transmitted - pkts_received ) / pkts_transmitted. + For bi-directional throughput tests aggregate PLR is calculated based + on the aggregate number of packets transmitted and received. +* Effective loss ratio: A corrected value of measured packet loss ratio + chosen to avoid difficulties if SUT exhibits decreasing loss + with increasing load. Maximum of packet loss ratios measured at the same + duration on all loads smaller than (and including) the current one. +* Target loss ratio: A packet loss ratio value acting as an input for search. + The search is finding tight enough lower and upper bound in intended load, + so that the lower bound has smaller or equal loss ratio, and upper bound + has strictly larger loss ratio. For the tightest upper bound, + the effective loss ratio is the same as packet loss ratio. + For the tightest lower bound, the effective loss ratio can be higher + than the packet loss ratio, but still not larger than the target loss ratio. +* Packet Throughput Rate: maximum packet offered load DUT/SUT forwards + within the specified Packet Loss Ratio (PLR). In many cases the rate + depends on the frame size processed by DUT/SUT. Hence packet + throughput rate MUST be quoted with specific frame size as received by + DUT/SUT during the measurement. For bi-directional tests, packet + throughput rate should be reported as aggregate for both directions. + Measured in packets-per-second (pps) or frames-per-second (fps), + equivalent metrics. +* Bandwidth Throughput Rate: a secondary metric calculated from packet + throughput rate using formula: bw_rate = pkt_rate * (frame_size + + L1_overhead) * 8, where L1_overhead for Ethernet includes preamble (8 + octets) and inter-frame gap (12 octets). For bi-directional tests, + bandwidth throughput rate should be reported as aggregate for both + directions. Expressed in bits-per-second (bps). +* Non Drop Rate (NDR): maximum packet/bandwidth throughput rate sustained + by DUT/SUT at PLR equal zero (zero packet loss) specific to tested + frame size(s). MUST be quoted with specific packet size as received by + DUT/SUT during the measurement. Packet NDR measured in + packets-per-second (or fps), bandwidth NDR expressed in + bits-per-second (bps). +* Partial Drop Rate (PDR): maximum packet/bandwidth throughput rate + sustained by DUT/SUT at PLR greater than zero (non-zero packet loss) + specific to tested frame size(s). MUST be quoted with specific packet + size as received by DUT/SUT during the measurement. Packet PDR + measured in packets-per-second (or fps), bandwidth PDR expressed in + bits-per-second (bps). +* Maximum Receive Rate (MRR): packet/bandwidth rate regardless of PLR + sustained by DUT/SUT under specified Maximum Transmit Rate (MTR) + packet load offered by traffic generator. MUST be quoted with both + specific packet size and MTR as received by DUT/SUT during the + measurement. Packet MRR measured in packets-per-second (or fps), + bandwidth MRR expressed in bits-per-second (bps). +* Trial: a single measurement step. See [RFC2544] section 23. +* Trial duration: amount of time over which packets are transmitted + in a single measurement step. + +# MLRsearch Background + +Multiple Loss Ratio search (MLRsearch) is a packet throughput search +algorithm suitable for deterministic systems (as opposed to +probabilistic systems). MLRsearch discovers multiple packet throughput +rates in a single search, each rate is associated with a distinct +Packet Loss Ratio (PLR) criterion. + +For cases when multiple rates need to be found, this property makes +MLRsearch more efficient in terms of time execution, compared to +traditional throughput search algorithms that discover a single packet +rate per defined search criteria (e.g. a binary search specified by +[RFC2544]). MLRsearch reduces execution time even further by relying on +shorter trial durations of intermediate steps, with only the final +measurements conducted at the specified final trial duration. This +results in the shorter overall search execution time when compared to a +traditional binary search, while guaranteeing the same results for +deterministic systems. + +In practice, two rates with distinct PLRs are commonly used for packet +throughput measurements of NFV systems: Non Drop Rate (NDR) with PLR=0 +and Partial Drop Rate (PDR) with PLR>0. The rest of this document +describes MLRsearch with NDR and PDR pair as an example. + +Similarly to other throughput search approaches like binary search, +MLRsearch is effective for SUTs/DUTs with PLR curve that is +non-decreasing with growing offered load. It may not be as +effective for SUTs/DUTs with abnormal PLR curves, although +it will always converge to some value. + +MLRsearch relies on traffic generator to qualify the received packet +stream as error-free, and invalidate the results if any disqualifying +errors are present e.g. out-of-sequence frames. + +MLRsearch can be applied to both uni-directional and bi-directional +throughput tests. + +For bi-directional tests, MLRsearch rates and ratios are aggregates of +both directions, based on the following assumptions: + +* Traffic transmitted by traffic generator and received by SUT/DUT + has the same packet rate in each direction, + in other words the offered load is symmetric. +* SUT/DUT packet processing capacity is the same in both directions, + resulting in the same packet loss under load. + +MLRsearch can be applied even without those assumptions, +but in that case the aggregate loss ratio is less useful as a metric. + +MLRsearch can be used for network transactions consisting of more than +just one packet, or anything else that has intended load as input +and loss ratio as output (duration as input is optional). +This text uses mostly packet-centric language. + +# MLRsearch Overview + +The main properties of MLRsearch: + +* MLRsearch is a duration aware multi-phase multi-rate search algorithm: + * Initial Phase determines promising starting interval for the search. + * Intermediate Phases progress towards defined final search criteria. + * Final Phase executes measurements according to the final search + criteria. + * Final search criteria are defined by following inputs: + * Target PLRs (e.g. 0.0 and 0.005 when searching for NDR and PDR). + * Final trial duration. + * Measurement resolution. +* Initial Phase: + * Measure MRR over initial trial duration. + * Measured MRR is used as an input to the first intermediate phase. +* Multiple Intermediate Phases: + * Trial duration: + * Start with initial trial duration in the first intermediate phase. + * Converge geometrically towards the final trial duration. + * Track all previous trial measurement results: + * Duration, offered load and loss ratio are tracked. + * Effective loss ratios are tracked. + * While in practice, real loss ratios can decrease with increasing load, + effective loss ratios never decrease. This is achieved by sorting + results by load, and using the effective loss ratio of the previous load + if the current loss ratio is smaller than that. + * The algorithm queries the results to find best lower and upper bounds. + * Effective loss ratios are always used. + * The phase ends if all target loss ratios have tight enough bounds. + * Search: + * Iterate over target loss ratios in increasing order. + * If both upper and lower bound are in measurement results for this duration, + apply bisect until the bounds are tight enough, + and continue with next loss ratio. + * If a bound is missing for this duration, but there exists a bound + from the previous duration (compatible with the other bound + at this duration), re-measure at the current duration. + * If a bound in one direction (upper or lower) is missing for this duration, + and the previous duration does not have a compatible bound, + compute the current "interval size" from the second tightest bound + in the other direction (lower or upper respectively) + for the current duration, and choose next offered load for external search. + * The logic guarantees that a measurement is never repeated with both + duration and offered load being the same. + * The logic guarantees that measurements for higher target loss ratio + iterations (still within the same phase duration) do not affect validity + and tightness of bounds for previous target loss ratio iterations + (at the same duration). + * Use of internal and external searches: + * External search: + * It is a variant of "exponential search". + * The "interval size" is multiplied by a configurable constant + (powers of two work well with the subsequent internal search). + * Internal search: + * A variant of binary search that measures at offered load between + the previously found bounds. + * The interval does not need to be split into exact halves, + if other split can get to the target width goal faster. + * The idea is to avoid returning interval narrower than the current + width goal. See sample implementation details, below. +* Final Phase: + * Executed with the final test trial duration, and the final width + goal that determines resolution of the overall search. +* Intermediate Phases together with the Final Phase are called + Non-Initial Phases. +* The returned bounds stay within prescribed min_rate and max_rate. + * When returning min_rate or max_rate, the returned bounds may be invalid. + * E.g. upper bound at max_rate may come from a measurement + with loss ratio still not higher than the target loss ratio. + +The main benefits of MLRsearch vs. binary search include: + +* In general, MLRsearch is likely to execute more trials overall, but + likely less trials at a set final trial duration. +* In well behaving cases, e.g. when results do not depend on trial + duration, it greatly reduces (>50%) the overall duration compared to a + single PDR (or NDR) binary search over duration, while finding + multiple drop rates. +* In all cases MLRsearch yields the same or similar results to binary + search. +* Note: both binary search and MLRsearch are susceptible to reporting + non-repeatable results across multiple runs for very bad behaving + cases. + +Caveats: + +* Worst case MLRsearch can take longer than a binary search, e.g. in case of + drastic changes in behaviour for trials at varying durations. + * Re-measurement at higher duration can trigger a long external search. + That never happens in binary search, which uses the final duration + from the start. + +# Sample Implementation + +Following is a brief description of a sample MLRsearch implementation, +which is a simplified version of the existing implementation. + +## Input Parameters + +1. **max_rate** - Maximum Transmit Rate (MTR) of packets to + be used by external traffic generator implementing MLRsearch, + limited by the actual Ethernet link(s) rate, NIC model or traffic + generator capabilities. +2. **min_rate** - minimum packet transmit rate to be used for + measurements. MLRsearch fails if lower transmit rate needs to be + used to meet search criteria. +3. **final_trial_duration** - required trial duration for final rate + measurements. +4. **initial_trial_duration** - trial duration for initial MLRsearch phase. +5. **final_relative_width** - required measurement resolution expressed as + (lower_bound, upper_bound) interval width relative to upper_bound. +6. **packet_loss_ratios** - list of maximum acceptable PLR search criteria. +7. **number_of_intermediate_phases** - number of phases between the initial + phase and the final phase. Impacts the overall MLRsearch duration. + Less phases are required for well behaving cases, more phases + may be needed to reduce the overall search duration for worse behaving cases. + +## Initial Phase + +1. First trial measures at configured maximum transmit rate (MTR) and + discovers maximum receive rate (MRR). + * IN: trial_duration = initial_trial_duration. + * IN: offered_transmit_rate = maximum_transmit_rate. + * DO: single trial. + * OUT: measured loss ratio. + * OUT: MRR = measured receive rate. + Received rate is computed as intended load multiplied by pass ratio + (which is one minus loss ratio). This is useful when loss ratio is computed + from a different metric than intended load. For example, intended load + can be in transactions (multiple packets each), but loss ratio is computed + on level of packets, not transactions. + + * Example: If MTR is 10 transactions per second, and each transaction has + 10 packets, and receive rate is 90 packets per second, then loss rate + is 10%, and MRR is computed to be 9 transactions per second. + + If MRR is too close to MTR, MRR is set below MTR so that interval width + is equal to the width goal of the first intermediate phase. + If MRR is less than min_rate, min_rate is used. +2. Second trial measures at MRR and discovers MRR2. + * IN: trial_duration = initial_trial_duration. + * IN: offered_transmit_rate = MRR. + * DO: single trial. + * OUT: measured loss ratio. + * OUT: MRR2 = measured receive rate. + If MRR2 is less than min_rate, min_rate is used. + If loss ratio is less or equal to the smallest target loss ratio, + MRR2 is set to a value above MRR, so that interval width is equal + to the width goal of the first intermediate phase. + MRR2 could end up being equal to MTR (for example if both measurements so far + had zero loss), which was already measured, step 3 is skipped in that case. +3. Third trial measures at MRR2. + * IN: trial_duration = initial_trial_duration. + * IN: offered_transmit_rate = MRR2. + * DO: single trial. + * OUT: measured loss ratio. + * OUT: MRR3 = measured receive rate. + If MRR3 is less than min_rate, min_rate is used. + If step 3 is not skipped, the first trial measurement is forgotten. + This is done because in practice (if MRR2 is above MRR), external search + from MRR and MRR2 is likely to lead to a faster intermediate phase + than a bisect between MRR2 and MTR. + +## Non-Initial Phases + +1. Main phase loop: + 1. IN: trial_duration for the current phase. Set to + initial_trial_duration for the first intermediate phase; to + final_trial_duration for the final phase; or to the element of + interpolating geometric sequence for other intermediate phases. + For example with two intermediate phases, trial_duration of the + second intermediate phase is the geometric average of + initial_trial_duration and final_trial_duration. + 2. IN: relative_width_goal for the current phase. Set to + final_relative_width for the final phase; doubled for each + preceding phase. For example with two intermediate phases, the + first intermediate phase uses quadruple of final_relative_width + and the second intermediate phase uses double of + final_relative_width. + 3. IN: Measurement results from the previous phase (previous duration). + 4. Internal target ratio loop: + 1. IN: Target loss ratio for this iteration of ratio loop. + 2. IN: Measurement results from all previous ratio loop iterations + of current phase (current duration). + 3. DO: According to the procedure described in point 2: + 1. either exit the phase (by jumping to 1.5), + 2. or exit loop iteration (by continuing with next target loss ratio, + jumping to 1.4.1), + 3. or calculate new transmit rate to measure with. + 4. DO: Perform the trial measurement at the new transmit rate and + current trial duration, compute its loss ratio. + 5. DO: Add the result and go to next iteration (1.4.1), + including the added trial result in 1.4.2. + 5. OUT: Measurement results from this phase. + 6. OUT: In the final phase, bounds for each target loss ratio + are extracted and returned. + 1. If a valid bound does not exist, use min_rate or max_rate. +2. New transmit rate (or exit) calculation (for point 1.4.3): + 1. If the previous duration has the best upper and lower bound, + select the middle point as the new transmit rate. + 1. See 2.5.3. below for the exact splitting logic. + 2. This can be a no-op if interval is narrow enough already, + in that case continue with 2.2. + 3. Discussion, assuming the middle point is selected and measured: + 1. Regardless of loss rate measured, the result becomes + either best upper or best lower bound at current duration. + 2. So this condition is satisfied at most once per iteration. + 3. This also explains why previous phase has double width goal: + 1. We avoid one more bisection at previous phase. + 2. At most one bound (per iteration) is re-measured + with current duration. + 3. Each re-measurement can trigger an external search. + 4. Such surprising external searches are the main hurdle + in achieving low overall search durations. + 5. Even without 1.1, there is at most one external search + per phase and target loss ratio. + 6. But without 1.1 there can be two re-measurements, + each coming with a risk of triggering external search. + 2. If the previous duration has one bound best, select its transmit rate. + In deterministic case this is the last measurement needed this iteration. + 3. If only upper bound exists in current duration results: + 1. This can only happen for the smallest target loss ratio. + 2. If the upper bound was measured at min_rate, + exit the whole phase early (not investigating other target loss ratios). + 3. Select new transmit rate using external search: + 1. For computing previous interval size, use: + 1. second tightest bound at current duration, + 2. or tightest bound of previous duration, + if compatible and giving a more narrow interval, + 3. or target interval width if none of the above is available. + 4. In any case increase to target interval width if smaller. + 2. Quadruple the interval width. + 3. Use min_rate if the new transmit rate is lower. + 4. If only lower bound exists in current duration results: + 1. If the lower bound was measured at max_rate, + exit this iteration (continue with next lowest target loss ratio). + 2. Select new transmit rate using external search: + 1. For computing previous interval size, use: + 1. second tightest bound at current duration, + 2. or tightest bound of previous duration, + if compatible and giving a more narrow interval, + 3. or target interval width if none of the above is available. + 4. In any case increase to target interval width if smaller. + 2. Quadruple the interval width. + 3. Use max_rate if the new transmit rate is higher. + 5. The only remaining option is both bounds in current duration results. + 1. This can happen in two ways, depending on how the lower bound + was chosen. + 1. It could have been selected for the current loss ratio, + e.g. in re-measurement (2.2) or in initial bisect (2.1). + 2. It could have been found as an upper bound for the previous smaller + target loss ratio, in which case it might be too low. + 3. The algorithm does not track which one is the case, + as the decision logic works well regardless. + 2. Compute "extending down" candidate transmit rate exactly as in 2.3. + 3. Compute "bisecting" candidate transmit rate: + 1. Compute the current interval width from the two bounds. + 2. Express the width as a (float) multiple of the target width goal + for this phase. + 3. If the multiple is not higher than one, it means the width goal + is met. Exit this iteration and continue with next higher + target loss ratio. + 4. If the multiple is two or less, use half of that + for new width if the lower subinterval. + 5. Round the multiple up to nearest even integer. + 6. Use half of that for new width if the lower subinterval. + 7. Example: If lower bound is 2.0 and upper bound is 5.0, and width + goal is 1.0, the new candidate transmit rate will be 4.0. + This can save a measurement when 4.0 has small loss. + Selecting the average (3.5) would never save a measurement, + giving more narrow bounds instead. + 4. If either candidate computation want to exit the iteration, + do as bisecting candidate computation says. + 5. The remaining case is both candidates wanting to measure at some rate. + Use the higher rate. This prefers external search down narrow enough + interval, competing with perfectly sized lower bisect subinterval. + +# FD.io CSIT Implementation + +The only known working implementation of MLRsearch is in +the open-source code running in Linux Foundation +FD.io CSIT project [FDio-CSIT-MLRsearch] as part of +a Continuous Integration / Continuous Development (CI/CD) framework. + +MLRsearch is also available as a Python package in [PyPI-MLRsearch]. + +## Additional details + +This document so far has been describing a simplified version of +MLRsearch algorithm. The full algorithm as implemented in CSIT contains +additional logic, which makes some of the details (but not general +ideas) above incorrect. Here is a short description of the additional +logic as a list of principles, explaining their main differences from +(or additions to) the simplified description, but without detailing +their mutual interaction. + +1. Logarithmic transmit rate. + * In order to better fit the relative width goal, the interval + doubling and halving is done differently. + * For example, the middle of 2 and 8 is 4, not 5. +2. Timeout for bad cases. + * The worst case for MLRsearch is when each phase converges to + intervals way different than the results of the previous phase. + * Rather than suffer total search time several times larger than pure + binary search, the implemented tests fail themselves when the + search takes too long (given by argument *timeout*). +3. Intended count. + * The number of packets to send during the trial should be equal to + the intended load multiplied by the duration. + * Also multiplied by a coefficient, if loss ratio is calculated + from a different metric. + * Example: If a successful transaction uses 10 packets, + load is given in transactions per second, but loss ratio is calculated + from packets, so the coefficient to get intended count of packets + is 10. + * But in practice that does not work. + * It could result in a fractional number of packets, + * so it has to be rounded in a way traffic generator chooses, + * which may depend on the number of traffic flows + and traffic generator worker threads. +4. Attempted count. As the real number of intended packets is not known exactly, + the computation uses the number of packets traffic generator reports as sent. + Unless overridden by the next point. +5. Duration stretching. + * In some cases, traffic generator may get overloaded, + causing it to take significantly longer (than duration) to send all packets. + * The implementation uses an explicit stop, + * causing lower attempted count in those cases. + * The implementation tolerates some small difference between + attempted count and intended count. + * 10 microseconds worth of traffic is sufficient for our tests. + * If the difference is higher, the unsent packets are counted as lost. + * This forces the search to avoid the regions of high duration stretching. + * The final bounds describe the performance of not just SUT, + but of the whole system, including the traffic generator. +6. Excess packets. + * In some test (e.g. using TCP flows) Traffic generator reacts to packet loss + by retransmission. Usually, such packet loss is already affecting loss ratio. + If a test also wants to treat retransmissions due to heavily delayed packets + also as a failure, this is once again visible as a mismatch between + the intended count and the attempted count. + * The CSIT implementation simply looks at absolute value of the difference, + so it offers the same small tolerance before it starts marking a "loss". +7. For result processing, we use lower bounds and ignore upper bounds. + +### FD.io CSIT Input Parameters + +1. **max_rate** - Typical values: 2 * 14.88 Mpps for 64B + 10GE link rate, 2 * 18.75 Mpps for 64B 40GE NIC (specific model). +2. **min_rate** - Value: 2 * 9001 pps (we reserve 9000 pps + for latency measurements). +3. **final_trial_duration** - Value: 30.0 seconds. +4. **initial_trial_duration** - Value: 1.0 second. +5. **final_relative_width** - Value: 0.005 (0.5%). +6. **packet_loss_ratios** - Value: 0.0, 0.005 (0.0% for NDR, 0.5% for PDR). +7. **number_of_intermediate_phases** - Value: 2. + The value has been chosen based on limited experimentation to date. + More experimentation needed to arrive to clearer guidelines. +8. **timeout** - Limit for the overall search duration (for one search). + If MLRsearch oversteps this limit, it immediately declares the test failed, + to avoid wasting even more time on a misbehaving SUT. + Value: 600.0 (seconds). +9. **expansion_coefficient** - Width multiplier for external search. + Value: 4.0 (interval width is quadroupled). + Value of 2.0 is best for well-behaved SUTs, but value of 4.0 has been found + to decrease overall search time for worse-behaved SUT configurations, + contributing more to the overall set of different SUT configurations tested. + + +## Example MLRsearch Run + + +The following list describes a search from a real test run in CSIT +(using the default input values as above). + +* Initial phase, trial duration 1.0 second. + +Measurement 1, intended load 18750000.0 pps (MTR), +measured loss ratio 0.7089514628479618 (valid upper bound for both NDR and PDR). + +Measurement 2, intended load 5457160.071600716 pps (MRR), +measured loss ratio 0.018650817320118702 (new tightest upper bounds). + +Measurement 3, intended load 5348832.933500009 pps (slightly less than MRR2 +in preparation for first intermediate phase target interval width), +measured loss ratio 0.00964383362905351 (new tightest upper bounds). + +* First intermediate phase starts, trial duration still 1.0 seconds. + +Measurement 4, intended load 4936605.579021453 pps (no lower bound, +performing external search downwards, for NDR), +measured loss ratio 0.0 (valid lower bound for both NDR and PDR). + +Measurement 5, intended load 5138587.208637197 pps (bisecting for NDR), +measured loss ratio 0.0 (new tightest lower bounds). + +Measurement 6, intended load 5242656.244044665 pps (bisecting), +measured loss ratio 0.013523745379347257 (new tightest upper bounds). + +* Both intervals are narrow enough. +* Second intermediate phase starts, trial duration 5.477225575051661 seconds. + +Measurement 7, intended load 5190360.904111567 pps (initial bisect for NDR), +measured loss ratio 0.0023533920869969953 (NDR upper bound, PDR lower bound). + +Measurement 8, intended load 5138587.208637197 pps (re-measuring NDR lower bound), +measured loss ratio 1.2080222912800403e-06 (new tightest NDR upper bound). + +* The two intervals have separate bounds from now on. + +Measurement 9, intended load 4936605.381062318 pps (external NDR search down), +measured loss ratio 0.0 (new valid NDR lower bound). + +Measurement 10, intended load 5036583.888432355 pps (NDR bisect), +measured loss ratio 0.0 (new tightest NDR lower bound). + +Measurement 11, intended load 5087329.903232804 pps (NDR bisect), +measured loss ratio 0.0 (new tightest NDR lower bound). + +* NDR interval is narrow enough, PDR interval not ready yet. + +Measurement 12, intended load 5242656.244044665 pps (re-measuring PDR upper bound), +measured loss ratio 0.0101174866190136 (still valid PDR upper bound). + +* Also PDR interval is narrow enough, with valid bounds for this duration. +* Final phase starts, trial duration 30.0 seconds. + +Measurement 13, intended load 5112894.3238511775 pps (initial bisect for NDR), +measured loss ratio 0.0 (new tightest NDR lower bound). + +Measurement 14, intended load 5138587.208637197 (re-measuring NDR upper bound), +measured loss ratio 2.030389804256833e-06 (still valid PDR upper bound). + +* NDR interval is narrow enough, PDR interval not yet. + +Measurement 15, intended load 5216443.04126728 pps (initial bisect for PDR), +measured loss ratio 0.005620871287975237 (new tightest PDR upper bound). + +Measurement 16, intended load 5190360.904111567 (re-measuring PDR lower bound), +measured loss ratio 0.0027629971184465604 (still valid PDR lower bound). + +* PDR interval is also narrow enough. +* Returning bounds: +* NDR_LOWER = 5112894.3238511775 pps; NDR_UPPER = 5138587.208637197 pps; +* PDR_LOWER = 5190360.904111567 pps; PDR_UPPER = 5216443.04126728 pps. + +# IANA Considerations + +No requests of IANA. + +# Security Considerations + +Benchmarking activities as described in this memo are limited to +technology characterization of a DUT/SUT using controlled stimuli in a +laboratory environment, with dedicated address space and the constraints +specified in the sections above. + +The benchmarking network topology will be an independent test setup and +MUST NOT be connected to devices that may forward the test traffic into +a production network or misroute traffic to the test management network. + +Further, benchmarking is performed on a "black-box" basis, relying +solely on measurements observable external to the DUT/SUT. + +Special capabilities SHOULD NOT exist in the DUT/SUT specifically for +benchmarking purposes. Any implications for network security arising +from the DUT/SUT SHOULD be identical in the lab and in production +networks. + +# Acknowledgements + +Many thanks to Alec Hothan of OPNFV NFVbench project for thorough +review and numerous useful comments and suggestions. + +--- back |