FreeBSD/Linux Kernel Cross Reference
sys/contrib/zstd/programs/benchfn.h

     /*
      * Copyright (c) Yann Collet, Facebook, Inc.
      * All rights reserved.
      *
      * This source code is licensed under both the BSD-style license (found in the
      * LICENSE file in the root directory of this source tree) and the GPLv2 (found
      * in the COPYING file in the root directory of this source tree).
      * You may select, at your option, one of the above-listed licenses.
      */
    
    
    /* benchfn :
     * benchmark any function on a set of input
     * providing result in nanoSecPerRun
     * or detecting and returning an error
     */
    
    #if defined (__cplusplus)
    extern "C" {
    #endif
    
    #ifndef BENCH_FN_H_23876
    #define BENCH_FN_H_23876
    
    /* ===  Dependencies  === */
    #include <stddef.h>   /* size_t */
    
    
    /* ====  Benchmark any function, iterated on a set of blocks  ==== */
    
    /* BMK_runTime_t: valid result return type */
    
    typedef struct {
        double nanoSecPerRun;  /* time per iteration (over all blocks) */
        size_t sumOfReturn;         /* sum of return values */
    } BMK_runTime_t;
    
    
    /* BMK_runOutcome_t:
     * type expressing the outcome of a benchmark run by BMK_benchFunction(),
     * which can be either valid or invalid.
     * benchmark outcome can be invalid if errorFn is provided.
     * BMK_runOutcome_t must be considered "opaque" : never access its members directly.
     * Instead, use its assigned methods :
     * BMK_isSuccessful_runOutcome, BMK_extract_runTime, BMK_extract_errorResult.
     * The structure is only described here to allow its allocation on stack. */
    
    typedef struct {
        BMK_runTime_t internal_never_ever_use_directly;
        size_t error_result_never_ever_use_directly;
        int error_tag_never_ever_use_directly;
    } BMK_runOutcome_t;
    
    
    /* prototypes for benchmarked functions */
    typedef size_t (*BMK_benchFn_t)(const void* src, size_t srcSize, void* dst, size_t dstCapacity, void* customPayload);
    typedef size_t (*BMK_initFn_t)(void* initPayload);
    typedef unsigned (*BMK_errorFn_t)(size_t);
    
    
    /* BMK_benchFunction() parameters are provided via the following structure.
     * A structure is preferable for readability,
     * as the number of parameters required is fairly large.
     * No initializer is provided, because it doesn't make sense to provide some "default" :
     * all parameters must be specified by the caller.
     * optional parameters are labelled explicitly, and accept value NULL when not used */
    typedef struct {
        BMK_benchFn_t benchFn;    /* the function to benchmark, over the set of blocks */
        void* benchPayload;       /* pass custom parameters to benchFn  :
                                   * (*benchFn)(srcBuffers[i], srcSizes[i], dstBuffers[i], dstCapacities[i], benchPayload) */
        BMK_initFn_t initFn;      /* (*initFn)(initPayload) is run once per run, at the beginning. */
        void* initPayload;        /* Both arguments can be NULL, in which case nothing is run. */
        BMK_errorFn_t errorFn;    /* errorFn will check each return value of benchFn over each block, to determine if it failed or not.
                                   * errorFn can be NULL, in which case no check is performed.
                                   * errorFn must return 0 when benchFn was successful, and >= 1 if it detects an error.
                                   * Execution is stopped as soon as an error is detected.
                                   * the triggering return value can be retrieved using BMK_extract_errorResult(). */
        size_t blockCount;        /* number of blocks to operate benchFn on.
                                   * It's also the size of all array parameters :
                                   * srcBuffers, srcSizes, dstBuffers, dstCapacities, blockResults */
        const void *const * srcBuffers; /* read-only array of buffers to be operated on by benchFn */
        const size_t* srcSizes;   /* read-only array containing sizes of srcBuffers */
        void *const * dstBuffers; /* array of buffers to be written into by benchFn. This array is not optional, it must be provided even if unused by benchfn. */
        const size_t* dstCapacities; /* read-only array containing capacities of dstBuffers. This array must be present. */
        size_t* blockResults;     /* Optional: store the return value of benchFn for each block. Use NULL if this result is not requested. */
    } BMK_benchParams_t;
    
    
    /* BMK_benchFunction() :
     * This function benchmarks benchFn and initFn, providing a result.
     *
     * params : see description of BMK_benchParams_t above.
     * nbLoops: defines number of times benchFn is run over the full set of blocks.
     *          Minimum value is 1. A 0 is interpreted as a 1.
     *
     * @return: can express either an error or a successful result.
     *          Use BMK_isSuccessful_runOutcome() to check if benchmark was successful.
     *          If yes, extract the result with BMK_extract_runTime(),
     *          it will contain :
    *              .sumOfReturn : the sum of all return values of benchFn through all of blocks
    *              .nanoSecPerRun : time per run of benchFn + (time for initFn / nbLoops)
    *          .sumOfReturn is generally intended for functions which return a # of bytes written into dstBuffer,
    *              in which case, this value will be the total amount of bytes written into dstBuffer.
    *
    * blockResults : when provided (!= NULL), and when benchmark is successful,
    *                params.blockResults contains all return values of `benchFn` over all blocks.
    *                when provided (!= NULL), and when benchmark failed,
    *                params.blockResults contains return values of `benchFn` over all blocks preceding and including the failed block.
    */
   BMK_runOutcome_t BMK_benchFunction(BMK_benchParams_t params, unsigned nbLoops);
   
   
   
   /* check first if the benchmark was successful or not */
   int BMK_isSuccessful_runOutcome(BMK_runOutcome_t outcome);
   
   /* If the benchmark was successful, extract the result.
    * note : this function will abort() program execution if benchmark failed !
    *        always check if benchmark was successful first !
    */
   BMK_runTime_t BMK_extract_runTime(BMK_runOutcome_t outcome);
   
   /* when benchmark failed, it means one invocation of `benchFn` failed.
    * The failure was detected by `errorFn`, operating on return values of `benchFn`.
    * Returns the faulty return value.
    * note : this function will abort() program execution if benchmark did not failed.
    *        always check if benchmark failed first !
    */
   size_t BMK_extract_errorResult(BMK_runOutcome_t outcome);
   
   
   
   /* ====  Benchmark any function, returning intermediate results  ==== */
   
   /* state information tracking benchmark session */
   typedef struct BMK_timedFnState_s BMK_timedFnState_t;
   
   /* BMK_benchTimedFn() :
    * Similar to BMK_benchFunction(), most arguments being identical.
    * Automatically determines `nbLoops` so that each result is regularly produced at interval of about run_ms.
    * Note : minimum `nbLoops` is 1, therefore a run may last more than run_ms, and possibly even more than total_ms.
    * Usage - initialize timedFnState, select benchmark duration (total_ms) and each measurement duration (run_ms)
    *         call BMK_benchTimedFn() repetitively, each measurement is supposed to last about run_ms
    *         Check if total time budget is spent or exceeded, using BMK_isCompleted_TimedFn()
    */
   BMK_runOutcome_t BMK_benchTimedFn(BMK_timedFnState_t* timedFnState,
                                     BMK_benchParams_t params);
   
   /* Tells if duration of all benchmark runs has exceeded total_ms
    */
   int BMK_isCompleted_TimedFn(const BMK_timedFnState_t* timedFnState);
   
   /* BMK_createTimedFnState() and BMK_resetTimedFnState() :
    * Create/Set BMK_timedFnState_t for next benchmark session,
    * which shall last a minimum of total_ms milliseconds,
    * producing intermediate results, paced at interval of (approximately) run_ms.
    */
   BMK_timedFnState_t* BMK_createTimedFnState(unsigned total_ms, unsigned run_ms);
   void BMK_resetTimedFnState(BMK_timedFnState_t* timedFnState, unsigned total_ms, unsigned run_ms);
   void BMK_freeTimedFnState(BMK_timedFnState_t* state);
   
   
   /* BMK_timedFnState_shell and BMK_initStatic_timedFnState() :
    * Makes it possible to statically allocate a BMK_timedFnState_t on stack.
    * BMK_timedFnState_shell is only there to allocate space,
    * never ever access its members.
    * BMK_timedFnState_t() actually accepts any buffer.
    * It will check if provided buffer is large enough and is correctly aligned,
    * and will return NULL if conditions are not respected.
    */
   #define BMK_TIMEDFNSTATE_SIZE 64
   typedef union {
       char never_access_space[BMK_TIMEDFNSTATE_SIZE];
       long long alignment_enforcer;  /* must be aligned on 8-bytes boundaries */
   } BMK_timedFnState_shell;
   BMK_timedFnState_t* BMK_initStatic_timedFnState(void* buffer, size_t size, unsigned total_ms, unsigned run_ms);
   
   
   #endif   /* BENCH_FN_H_23876 */
   
   #if defined (__cplusplus)
   }
   #endif

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