TABLE OF CONTENTS

1. Component Library/Performance Counters
2. Component Library: Performance Counters/PERF_DECLARE
3. Component Library: Performance Counters/PERF_DECLARE_START
4. Component Library: Performance Counters/cl_perf_construct
5. Component Library: Performance Counters/cl_perf_destroy
6. Component Library: Performance Counters/cl_perf_display
7. Component Library: Performance Counters/cl_perf_init
8. Component Library: Performance Counters/cl_perf_log
9. Component Library: Performance Counters/cl_perf_reset
10. Component Library: Performance Counters/cl_perf_start
11. Component Library: Performance Counters/cl_perf_stop
12. Component Library: Performance Counters/cl_perf_update

Component Library/Performance Counters

    Performance Counters

    The performance counters allows timing operations to benchmark
    software performance and help identify potential bottlenecks.

    All performance counters are NULL macros when disabled, preventing them
    from adversly affecting performance in builds where the counters are not
    used.

    Each counter records elapsed time in micro-seconds, minimum time elapsed,
    and total number of samples.

    Each counter is independently protected by a spinlock, allowing use of
    the counters in multi-processor environments.

    The impact of serializing access to performance counters is measured,
    allowing measurements to be corrected as necessary.

    Performance counters do impact performance, and should only be enabled
    when gathering data.  Counters can be enabled or disabled on a per-user
    basis at compile time.  To enable the counters, users should define
    the PERF_TRACK_ON keyword before including the cl_perf.h file.  
    Undefining the PERF_TRACK_ON keyword disables the performance counters.
    When disabled, all performance tracking calls resolve to no-ops.

    When using performance counters, it is the user's responsibility to
    maintain the counter indexes.  It is recomended that users define an 
    enumerated type to use for counter indexes.  It improves readability 
    and simplifies maintenance by reducing the work necessary in managing 
    the counter indexes.

    Structures:
        cl_perf_t

    Initialization:
        cl_perf_construct, cl_perf_init, cl_perf_destroy

    Manipulation
        cl_perf_reset, cl_perf_display, cl_perf_start, cl_perf_update, 
        cl_perf_log, cl_perf_stop

    Macros:
        PERF_DECLARE, PERF_DECLARE_START

Component Library: Performance Counters/PERF_DECLARE

    PERF_DECLARE

    The PERF_DECLARE macro declares a performance counter variable used
    to store the starting time of a timing sequence.

    PERF_DECLARE( index )

    index
        [in] Index of the performance counter for which to use this
        variable.

    Variables should generally be declared on the stack to support 
    multi-threading.  In cases where a counter needs to be used to
    time operations accross multiple functions, care must be taken to
    ensure that the start time stored in this variable is not overwritten
    before the related performance counter has been updated.

    This macro has no effect when performance counters are disabled.

    Performance Counters, PERF_DECLARE_START, cl_perf_start, cl_perf_log,
    cl_perf_stop

Component Library: Performance Counters/PERF_DECLARE_START

    PERF_DECLARE_START

    The PERF_DECLARE_START macro declares a performance counter variable 
    and sets it to the starting time of a timed sequence.

    PERF_DECLARE_START( index )

    index
        [in] Index of the performance counter for which to use this
        variable.

    Variables should generally be declared on the stack to support 
    multi-threading.  

    This macro has no effect when performance counters are disabled.

    Performance Counters, PERF_DECLARE, cl_perf_start, cl_perf_log, 
    cl_perf_stop

Component Library: Performance Counters/cl_perf_construct

    cl_perf_construct

    The cl_perf_construct macro constructs a performance 
    tracking container.

void
cl_perf_construct(
    IN  cl_perf_t* const    p_perf );

    p_perf
        [in] Pointer to a performance counter container to construct.

    This function does not return a value.

    cl_perf_construct allows calling cl_perf_destroy without first calling 
    cl_perf_init.

    Calling cl_perf_construct is a prerequisite to calling any other
    perfromance counter function except cl_perf_init.

    This function is implemented as a macro and has no effect when 
    performance counters are disabled.

    Performance Counters, cl_perf_init, cl_perf_destroy

Component Library: Performance Counters/cl_perf_destroy

    cl_perf_destroy

    The cl_perf_destroy function destroys a performance tracking container.

void
cl_perf_destroy(
    IN  cl_perf_t* const    p_perf,
    IN  const boolean_t     display );

    p_perf
        [in] Pointer to a performance counter container to destroy.

    display
        [in] If TRUE, causes the performance counters to be displayed.

    This function does not return a value.

    cl_perf_destroy frees all resources allocated in a call to cl_perf_init.
    If the display parameter is set to TRUE, displays all counter values 
    before deallocating resources.

    This function should only be called after a call to cl_perf_construct 
    or cl_perf_init.

    This function is implemented as a macro and has no effect when 
    performance counters are disabled.

    Performance Counters, cl_perf_construct, cl_perf_init

Component Library: Performance Counters/cl_perf_display

    cl_perf_display

    The cl_perf_display function displays the current performance 
    counter values.

void
cl_perf_display(
    IN  const cl_perf_t* const  p_perf );

    p_perf
        [in] Pointer to a performance counter container whose counter 
        values to display.

    This function does not return a value.

    This function is implemented as a macro and has no effect when 
    performance counters are disabled.

    Performance Counters, cl_perf_init

Component Library: Performance Counters/cl_perf_init

    cl_perf_init

    The cl_perf_init function initializes a performance counter container
    for use.

cl_status_t
cl_perf_init(
    IN  cl_perf_t* const    p_perf,
    IN  const uintn_t       num_counters );

    p_perf
        [in] Pointer to a performance counter container to initalize.

    num_cntrs
        [in] Number of counters to allocate in the container.

    CL_SUCCESS if initialization was successful.

    CL_INSUFFICIENT_MEMORY if there was not enough memory to initialize
    the container.

    CL_ERROR if an error was encountered initializing the locks for the
    performance counters.

    This function allocates all memory required for the requested number of
    counters and initializes all locks protecting those counters.  After a 
    successful initialization, cl_perf_init calibrates the counters and
    resets their value.

    This function is implemented as a macro and has no effect when 
    performance counters are disabled.

    Performance Counters, cl_perf_construct, cl_perf_destroy, cl_perf_display

Component Library: Performance Counters/cl_perf_log

    cl_perf_log

    The cl_perf_log macro adds a given timing sample to a 
    counter in a performance counter container.

void
cl_perf_log(
    IN  cl_perf_t* const    p_perf,
    IN  const uintn_t       index, 
    IN  const uint64_t      pc_total_time );

    p_perf
        [in] Pointer to a performance counter container to whose counter 
        the sample should be added.

    index
        [in] Number of the performance counter to update with a new sample.

    pc_total_time
        [in] Total elapsed time for the sample being added.

    This function does not return a value.

    This macro has no effect when performance counters are disabled.

    Performance Counters, PERF_DECLARE, PERF_DECLARE_START, cl_perf_start, 
    cl_perf_update, cl_perf_stop

Component Library: Performance Counters/cl_perf_reset

    cl_perf_reset

    The cl_perf_reset function resets the counters contained in 
    a performance tracking container.

void
cl_perf_reset(
    IN  cl_perf_t* const    p_perf );

    p_perf
        [in] Pointer to a performance counter container whose counters 
        to reset.

    This function does not return a value.

    This function is implemented as a macro and has no effect when 
    performance counters are disabled.

    Performance Counters

Component Library: Performance Counters/cl_perf_start

    cl_perf_start

    The cl_perf_start macro sets the starting value of a timed sequence.

void
cl_perf_start(
    IN  const uintn_t index );

    index
        [in] Index of the performance counter to set.

    This macro has no effect when performance counters are disabled.

    Performance Counters, PERF_DECLARE, PERF_DECLARE_START, cl_perf_log, 
    cl_perf_update, cl_perf_stop

Component Library: Performance Counters/cl_perf_stop

    cl_perf_stop

    The cl_perf_log macro updates a counter in a performance counter 
    container with a new timing sample.

void
cl_perf_stop(
    IN  cl_perf_t* const    p_perf,
    IN  const uintn_t       index );

    p_perf
        [in] Pointer to a performance counter container to whose counter 
        a sample should be added.

    index
        [in] Number of the performance counter to update with a new sample.

    This function does not return a value.

    The ending time stamp is taken and elapsed time calculated before updating
    the specified counter.

    This macro has no effect when performance counters are disabled.

    Performance Counters, PERF_DECLARE, PERF_DECLARE_START, cl_perf_start, 
    cl_perf_log

Component Library: Performance Counters/cl_perf_update

    cl_perf_update

    The cl_perf_update macro adds a timing sample based on a provided start 
    time to a counter in a performance counter container.

void
cl_perf_update(
    IN  cl_perf_t* const    p_perf,
    IN  const uintn_t       index, 
    IN  const uint64_t      start_time );

    p_perf
        [in] Pointer to a performance counter container to whose counter 
        the sample should be added.

    index
        [in] Number of the performance counter to update with a new sample.

    start_time
        [in] Timestamp to use as the start time for the timing sample.

    This function does not return a value.

    This macro has no effect when performance counters are disabled.

    Performance Counters, PERF_DECLARE, PERF_DECLARE_START, cl_perf_start, 
    cl_perf_lob, cl_perf_stop