Activity Params

Activity parameters are passed as named arguments for an activity, either on the command line or via a scenario script. On the command line, these take the form of


Some activity parameters are universal in that they can be used with any activity type. These parameters are recognized by EngineBlock whether or not they are recognized by a particular activity type implementation. These are called universal activity parameters. Only universal activity parameters are documented here.


type=<activity type>

You must set the type parameter for every activity so that EngineBlock knows which activity implementation to use.

This tells EngineBlock which activity type will be run for the provided parameters. This is used, for example, with the run or start commands. An activity of the named type will be initialized, and then further activity parameters on the command line will be used to configure it before it is started.

The available activity types can be discovered with the --list-activity-types global option.



You should set the alias parameter when you have multiple activities, when you want to name metrics per-activity, or when you want to control activities via scripting.

Each activity can be given a symbolic name known as an alias. It is good practice to give all your activities an alias, since this determines the named used in logging, metrics, and even scripting control.

default value : If the activity supports YAML config, then any provided YAML filename is used as the basis for the default alias. Otherwise, the activity type name is used. This is a convenience for simple test scenarios only.



You should set the threads parameter when you need to ramp up a workload.

Each activity can be created with a number of threads. It is important to adjust this setting to the system types used by EngineBlock.

default value : For now, the default is simply 1. Users must be aware of this setting and adjust it to a reasonable value for their workloads.


cycles=<cycle count>

cycles=<cycle min>..<cycle max>

You should set the cycles for every activity. Not setting it means that only one or a few cycles will run, constituting a sanity check at best.

The cycles parameter determines the starting and ending point for an activity. In the cycles=<cycle count> version, the count indicates the total number of cycles, and is equivalent to cycles=0..<cycle max>. In both cases, the max value is not the actual number of the last cycle. This is because all cycle parameters define a closed-open interval. In other words, the minimum value is either zero by default or the specified minimum value, but the maximum value is the first value not included in the interval. This means that you can easily stack intervals over subsequent runs while knowing that you will cover all logical cycles without gaps or duplicates. For example, given cycles=1000 and then cycles=1000..2000, and then cycles=2000..5K, you know that all cycles between 0 (inclusive) and 5000 (exclusive) have been specified.


striderate=1000 - use stride rate limiter for 1000 ops/s.

striderate=1000,0.0 - same as above, with scheduling strictness 0.0 (the default)

striderate=1000,0.0,co - same as above, but with scheduling delay included in latency metrics.

co_striderate=1000 - An alternate form for the ,co setting above.

This sets the target rate for strides. In EngineBlock, a stride is a group of operations that are dispatched and executed together within the same thread. This is useful, for example, to emulate application behaviors in which some outside request translates to multiple internal requests. It is also a way to optimize a client runtime for more efficiency and throughput. The stride rate limiter applies to the whole activity irrespective of how many threads it has.

The three-parameter form includes the ops/s target rate, a scheduling strictness parameter between 0.0 and 1.0, and an optional flag to enable coordinated omission compensation for latency metrics. Regardless of whether coordinated omission is included in latency metrics, the rate limiter still publishes a guage metric that shows the cumulative scheduling delay behind the target rate. The co option simply tells the latency metrics whether or not to include this value per-operation, or more precisely, per-stride in this case.

Only strictness values of 0.0 are allowed at this time. When strict rate limiting is better tested and documented, values up to 1.0 will be enabled.

It is not ideal to combine multiple rates with the co option applied unless you are strictly aligning the rates to the number of strides, cycles, or phases.


The targetrate parameter is a synonym for cyclerate, below.


cyclerate=1000 or targetrate=1000 - set the cycle rate limiter to 1000 ops/s.

cyclerate=1000,0.0 or targetrate=1000,0.0 - same as above, but with strictness set to 0.0 (the default)

cyclerate=1000,0.0,co or targetrate=1000,0.0,co - same as above but with scheduling delay included in latency metrics.

This sets the rate limit for individual cycles within the activity, across the whole activity, irrespective of how many threads are active. Cycles are the individual units of work within an EngineBlock activity which we normally think of as operations. As with the stride rate limiter above, the co option enables the inclusion of scheduling delay in latency metrics. In any case, the cycle rate limiter will provide a gauge metric that shows the total internal scheduling delay as compared to the target op rate.

Only strictness values of 0.0 are allowed at this time. When strict rate limiting is better tested and documented, values up to 1.0 will be enabled.

It is not ideal to combine multiple rates with the co option applied unless you are strictly aligning the rates to the number of strides, cycles, or phases.


phaserate=1000 - set the phase rate limiter to 1000 ops/s.

phaserate=1000,0.0 - same as above, but with a schedule strictness of 0.0 (the default)

phaserate=1000,0.0,co - same as above, but with scheduling delay included in latency metrics

co_phaserate=1000 - an alternate form for specifying the ,co option.

This sets the rate limit for phases. A phase is a sub-cycle unit of work which is sometimes used to implement things like async protocols, data paging, or other types of workloads which could not be expressed as well with only cycles.

Only strictness values of 0.0 are allowed at this time. When strict rate limiting is better tested and documented, values up to 1.0 will be enabled.

It is not ideal to combine multiple rates with the co option applied unless you are strictly aligning the rates to the number of strides, cycles, or phases.



This activity parameter set the default sequencing scheme for ratios. When ratios are used in a YAML config, a sequencer planner uses the assigned ratios to create a sequence of operations. Presently, seq is only an activity parameter, as it is not yet possible to have more than one type of sequencer over the statements in a single activity.

There are currently three different kinds of sequence planners:

  • bucket - This is a round robin planner which draws operations from buckets in circular fashion, removing each bucket as it is exhausted. For example, the ratios A:4, B:2, C:1 would yield the sequence A B C A B A A. The ratios A:1, B5 would yield the sequence A B B B B B.

  • concat - This simply takes each statement as it occurs in order and duplicates it in place to achieve the ratio. The ratios above (A:4, B:2, C:1) would yield the sequence A A A A B B C for the concat sequencer.

  • interval - This is arguably the most complex sequencer. It takes each ratio as a frequency over a unit interval of time, and apportions the associated operation to occur evenly over that time. When two operations would be assigned the same time, then the order of appearance establishes precedence. In other words, statements appearing first win ties for the same time slot. The ratios A:4 B:2 C:1 would yield the sequence A B C A A B A. This occurs because, over the unit interval (0.0,1.0), A is assigned the positions [0.0, 0.25, 0.5, 0.75], B is assigned the positions [0.0, 0.5], and C is assigned position [0.0]. These offsets are all sorted with a position-stable sort, and then the associated ops are taken as the order. In detail, the rendering appears thus: [0.0(A), 0.0(B), 0.0©, 0.25(A), 0.5(A), 0.5(B), 0.75(A)] which yields A B C A A B A. This sequencer is most useful when you want a stable ordering of operations from a rich mix of statement types, where each operations is spaced as evenly as possible over time, and where it is not important to control the cycle-by-cycle sequencing of statements.

Parameters which are documented below are for advanced testing scenarios. If you are a first-time EngineBlock user, it is recommended that you get familiar with the parameters above first. These parameters can unlock some of the advanced testing capabilities of EngineBlock, although they are not necessary for general performance testing.


input=type:<input type>[,...]

You may use input instead of cycles when needed for advanced test scenarios.

Every activity requires a set of cycle numbers on which to operate. The default interval-based input simply provides a set of cycles from a closed-open interval. Sometimes you need to control the cycles in a more specific way, say, for testing exceptional cases from a previous run.

The input activity parameter allows for reflection-based configuration of the input data source for an activity. The sub-parameters for input are dependent on the specific input implementation. To see those, use --list-input-types.

Example: input=type:cyclelog,file=lastrun

The cycles parameter acts as shorthand for configuring a basic interval-based input when no other input type is specified. It is essential equivalent to input=type:core,cycles=<cycles>.




You may use inputfilter when input has also been specified.

Some input types allow for filtering of the values on input according to a filter.


output=type:<output type>[,...]

You may use output in order to capture the per-cycle results of a test to a buffer or file.

EngineBlock activities can yield a result status ordinal that is a simple integer value. This can be useful, for example, to record the status of individual cycles according to a result mapping for that activity. By default, the output values are discarded. With the output parameter, you can specify a reflection-based output handler that will do something specific with the output values. To see the supported output types, use --list-output-types.

Example: output=type:cyclelog,file=testcycles




You may use outputfilter if output has also been specified.

If an output is used, then an output filter can be provided that will filter results before any further downstream handling, like writing to a logfile, for example.