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1 /*
2     bench.c - Demo program to benchmark open-source compression algorithms
3     Copyright (C) Yann Collet 2012-2016
4 
5     GPL v2 License
6 
7     This program is free software; you can redistribute it and/or modify
8     it under the terms of the GNU General Public License as published by
9     the Free Software Foundation; either version 2 of the License, or
10     (at your option) any later version.
11 
12     This program is distributed in the hope that it will be useful,
13     but WITHOUT ANY WARRANTY; without even the implied warranty of
14     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
15     GNU General Public License for more details.
16 
17     You should have received a copy of the GNU General Public License along
18     with this program; if not, write to the Free Software Foundation, Inc.,
19     51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
20 
21     You can contact the author at :
22     - LZ4 homepage : http://www.lz4.org
23     - LZ4 source repository : https://github.com/lz4/lz4
24 */
25 
26 
27 /*-************************************
28 *  Compiler options
29 **************************************/
30 #ifdef _MSC_VER    /* Visual Studio */
31 #  pragma warning(disable : 4127)    /* disable: C4127: conditional expression is constant */
32 #endif
33 
34 
35 /* *************************************
36 *  Includes
37 ***************************************/
38 #include "platform.h"    /* Compiler options */
39 #include "util.h"        /* UTIL_GetFileSize, UTIL_sleep */
40 #include <stdlib.h>      /* malloc, free */
41 #include <string.h>      /* memset */
42 #include <stdio.h>       /* fprintf, fopen, ftello */
43 #include <time.h>        /* clock_t, clock, CLOCKS_PER_SEC */
44 
45 #include "datagen.h"     /* RDG_genBuffer */
46 #include "xxhash.h"
47 
48 
49 #include "lz4.h"
50 #define COMPRESSOR0 LZ4_compress_local
LZ4_compress_local(const char * src,char * dst,int srcSize,int dstSize,int clevel)51 static int LZ4_compress_local(const char* src, char* dst, int srcSize, int dstSize, int clevel) { (void)clevel; return LZ4_compress_default(src, dst, srcSize, dstSize); }
52 #include "lz4hc.h"
53 #define COMPRESSOR1 LZ4_compress_HC
54 #define DEFAULTCOMPRESSOR COMPRESSOR0
55 #define LZ4_isError(errcode) (errcode==0)
56 
57 
58 /* *************************************
59 *  Constants
60 ***************************************/
61 #ifndef LZ4_GIT_COMMIT_STRING
62 #  define LZ4_GIT_COMMIT_STRING ""
63 #else
64 #  define LZ4_GIT_COMMIT_STRING LZ4_EXPAND_AND_QUOTE(LZ4_GIT_COMMIT)
65 #endif
66 
67 #define NBSECONDS             3
68 #define TIMELOOP_MICROSEC     1*1000000ULL /* 1 second */
69 #define ACTIVEPERIOD_MICROSEC 70*1000000ULL /* 70 seconds */
70 #define COOLPERIOD_SEC        10
71 #define DECOMP_MULT           2 /* test decompression DECOMP_MULT times longer than compression */
72 
73 #define KB *(1 <<10)
74 #define MB *(1 <<20)
75 #define GB *(1U<<30)
76 
77 static const size_t maxMemory = (sizeof(size_t)==4)  ?  (2 GB - 64 MB) : (size_t)(1ULL << ((sizeof(size_t)*8)-31));
78 
79 static U32 g_compressibilityDefault = 50;
80 
81 
82 /* *************************************
83 *  console display
84 ***************************************/
85 #define DISPLAY(...)         fprintf(stderr, __VA_ARGS__)
86 #define DISPLAYLEVEL(l, ...) if (g_displayLevel>=l) { DISPLAY(__VA_ARGS__); }
87 static U32 g_displayLevel = 2;   /* 0 : no display;   1: errors;   2 : + result + interaction + warnings;   3 : + progression;   4 : + information */
88 
89 #define DISPLAYUPDATE(l, ...) if (g_displayLevel>=l) { \
90             if ((clock() - g_time > refreshRate) || (g_displayLevel>=4)) \
91             { g_time = clock(); DISPLAY(__VA_ARGS__); \
92             if (g_displayLevel>=4) fflush(stdout); } }
93 static const clock_t refreshRate = CLOCKS_PER_SEC * 15 / 100;
94 static clock_t g_time = 0;
95 
96 
97 /* *************************************
98 *  Exceptions
99 ***************************************/
100 #ifndef DEBUG
101 #  define DEBUG 0
102 #endif
103 #define DEBUGOUTPUT(...) if (DEBUG) DISPLAY(__VA_ARGS__);
104 #define EXM_THROW(error, ...)                                             \
105 {                                                                         \
106     DEBUGOUTPUT("Error defined at %s, line %i : \n", __FILE__, __LINE__); \
107     DISPLAYLEVEL(1, "Error %i : ", error);                                \
108     DISPLAYLEVEL(1, __VA_ARGS__);                                         \
109     DISPLAYLEVEL(1, "\n");                                                \
110     exit(error);                                                          \
111 }
112 
113 
114 /* *************************************
115 *  Benchmark Parameters
116 ***************************************/
117 static U32 g_nbSeconds = NBSECONDS;
118 static size_t g_blockSize = 0;
119 int g_additionalParam = 0;
120 
BMK_setNotificationLevel(unsigned level)121 void BMK_setNotificationLevel(unsigned level) { g_displayLevel=level; }
122 
BMK_setAdditionalParam(int additionalParam)123 void BMK_setAdditionalParam(int additionalParam) { g_additionalParam=additionalParam; }
124 
BMK_SetNbSeconds(unsigned nbSeconds)125 void BMK_SetNbSeconds(unsigned nbSeconds)
126 {
127     g_nbSeconds = nbSeconds;
128     DISPLAYLEVEL(3, "- test >= %u seconds per compression / decompression -\n", g_nbSeconds);
129 }
130 
BMK_SetBlockSize(size_t blockSize)131 void BMK_SetBlockSize(size_t blockSize)
132 {
133     g_blockSize = blockSize;
134 }
135 
136 
137 /* ********************************************************
138 *  Bench functions
139 **********************************************************/
140 typedef struct {
141     const char* srcPtr;
142     size_t srcSize;
143     char*  cPtr;
144     size_t cRoom;
145     size_t cSize;
146     char*  resPtr;
147     size_t resSize;
148 } blockParam_t;
149 
150 struct compressionParameters
151 {
152     int (*compressionFunction)(const char* src, char* dst, int srcSize, int dstSize, int cLevel);
153 };
154 
155 #define MIN(a,b) ((a)<(b) ? (a) : (b))
156 #define MAX(a,b) ((a)>(b) ? (a) : (b))
157 
BMK_benchMem(const void * srcBuffer,size_t srcSize,const char * displayName,int cLevel,const size_t * fileSizes,U32 nbFiles)158 static int BMK_benchMem(const void* srcBuffer, size_t srcSize,
159                         const char* displayName, int cLevel,
160                         const size_t* fileSizes, U32 nbFiles)
161 {
162     size_t const blockSize = (g_blockSize>=32 ? g_blockSize : srcSize) + (!srcSize) /* avoid div by 0 */ ;
163     U32 const maxNbBlocks = (U32) ((srcSize + (blockSize-1)) / blockSize) + nbFiles;
164     blockParam_t* const blockTable = (blockParam_t*) malloc(maxNbBlocks * sizeof(blockParam_t));
165     size_t const maxCompressedSize = LZ4_compressBound((int)srcSize) + (maxNbBlocks * 1024);   /* add some room for safety */
166     void* const compressedBuffer = malloc(maxCompressedSize);
167     void* const resultBuffer = malloc(srcSize);
168     U32 nbBlocks;
169     UTIL_time_t ticksPerSecond;
170     struct compressionParameters compP;
171     int cfunctionId;
172 
173     /* checks */
174     if (!compressedBuffer || !resultBuffer || !blockTable)
175         EXM_THROW(31, "allocation error : not enough memory");
176 
177     /* init */
178     if (strlen(displayName)>17) displayName += strlen(displayName)-17;   /* can only display 17 characters */
179     UTIL_initTimer(&ticksPerSecond);
180 
181     /* Init */
182     if (cLevel < LZ4HC_CLEVEL_MIN) cfunctionId = 0; else cfunctionId = 1;
183     switch (cfunctionId)
184     {
185 #ifdef COMPRESSOR0
186     case 0 : compP.compressionFunction = COMPRESSOR0; break;
187 #endif
188 #ifdef COMPRESSOR1
189     case 1 : compP.compressionFunction = COMPRESSOR1; break;
190 #endif
191     default : compP.compressionFunction = DEFAULTCOMPRESSOR;
192     }
193 
194     /* Init blockTable data */
195     {   const char* srcPtr = (const char*)srcBuffer;
196         char* cPtr = (char*)compressedBuffer;
197         char* resPtr = (char*)resultBuffer;
198         U32 fileNb;
199         for (nbBlocks=0, fileNb=0; fileNb<nbFiles; fileNb++) {
200             size_t remaining = fileSizes[fileNb];
201             U32 const nbBlocksforThisFile = (U32)((remaining + (blockSize-1)) / blockSize);
202             U32 const blockEnd = nbBlocks + nbBlocksforThisFile;
203             for ( ; nbBlocks<blockEnd; nbBlocks++) {
204                 size_t const thisBlockSize = MIN(remaining, blockSize);
205                 blockTable[nbBlocks].srcPtr = srcPtr;
206                 blockTable[nbBlocks].cPtr = cPtr;
207                 blockTable[nbBlocks].resPtr = resPtr;
208                 blockTable[nbBlocks].srcSize = thisBlockSize;
209                 blockTable[nbBlocks].cRoom = LZ4_compressBound((int)thisBlockSize);
210                 srcPtr += thisBlockSize;
211                 cPtr += blockTable[nbBlocks].cRoom;
212                 resPtr += thisBlockSize;
213                 remaining -= thisBlockSize;
214     }   }   }
215 
216     /* warmimg up memory */
217     RDG_genBuffer(compressedBuffer, maxCompressedSize, 0.10, 0.50, 1);
218 
219     /* Bench */
220     {   U64 fastestC = (U64)(-1LL), fastestD = (U64)(-1LL);
221         U64 const crcOrig = XXH64(srcBuffer, srcSize, 0);
222         UTIL_time_t coolTime;
223         U64 const maxTime = (g_nbSeconds * TIMELOOP_MICROSEC) + 100;
224         U64 totalCTime=0, totalDTime=0;
225         U32 cCompleted=0, dCompleted=0;
226 #       define NB_MARKS 4
227         const char* const marks[NB_MARKS] = { " |", " /", " =",  "\\" };
228         U32 markNb = 0;
229         size_t cSize = 0;
230         double ratio = 0.;
231 
232         UTIL_getTime(&coolTime);
233         DISPLAYLEVEL(2, "\r%79s\r", "");
234         while (!cCompleted | !dCompleted) {
235             UTIL_time_t clockStart;
236             U64 clockLoop = g_nbSeconds ? TIMELOOP_MICROSEC : 1;
237 
238             /* overheat protection */
239             if (UTIL_clockSpanMicro(coolTime, ticksPerSecond) > ACTIVEPERIOD_MICROSEC) {
240                 DISPLAYLEVEL(2, "\rcooling down ...    \r");
241                 UTIL_sleep(COOLPERIOD_SEC);
242                 UTIL_getTime(&coolTime);
243             }
244 
245             /* Compression */
246             DISPLAYLEVEL(2, "%2s-%-17.17s :%10u ->\r", marks[markNb], displayName, (U32)srcSize);
247             if (!cCompleted) memset(compressedBuffer, 0xE5, maxCompressedSize);  /* warm up and erase result buffer */
248 
249             UTIL_sleepMilli(1);  /* give processor time to other processes */
250             UTIL_waitForNextTick(ticksPerSecond);
251             UTIL_getTime(&clockStart);
252 
253             if (!cCompleted) {   /* still some time to do compression tests */
254                 U32 nbLoops = 0;
255                 do {
256                     U32 blockNb;
257                     for (blockNb=0; blockNb<nbBlocks; blockNb++) {
258                         size_t const rSize = compP.compressionFunction(blockTable[blockNb].srcPtr, blockTable[blockNb].cPtr, (int)blockTable[blockNb].srcSize, (int)blockTable[blockNb].cRoom, cLevel);
259                         if (LZ4_isError(rSize)) EXM_THROW(1, "LZ4_compress() failed");
260                         blockTable[blockNb].cSize = rSize;
261                     }
262                     nbLoops++;
263                 } while (UTIL_clockSpanMicro(clockStart, ticksPerSecond) < clockLoop);
264                 {   U64 const clockSpan = UTIL_clockSpanMicro(clockStart, ticksPerSecond);
265                     if (clockSpan < fastestC*nbLoops) fastestC = clockSpan / nbLoops;
266                     totalCTime += clockSpan;
267                     cCompleted = totalCTime>maxTime;
268             }   }
269 
270             cSize = 0;
271             { U32 blockNb; for (blockNb=0; blockNb<nbBlocks; blockNb++) cSize += blockTable[blockNb].cSize; }
272             cSize += !cSize;  /* avoid div by 0 */
273             ratio = (double)srcSize / (double)cSize;
274             markNb = (markNb+1) % NB_MARKS;
275             DISPLAYLEVEL(2, "%2s-%-17.17s :%10u ->%10u (%5.3f),%6.1f MB/s\r",
276                     marks[markNb], displayName, (U32)srcSize, (U32)cSize, ratio,
277                     (double)srcSize / fastestC );
278 
279             (void)fastestD; (void)crcOrig;   /*  unused when decompression disabled */
280 #if 1
281             /* Decompression */
282             if (!dCompleted) memset(resultBuffer, 0xD6, srcSize);  /* warm result buffer */
283 
284             UTIL_sleepMilli(1); /* give processor time to other processes */
285             UTIL_waitForNextTick(ticksPerSecond);
286             UTIL_getTime(&clockStart);
287 
288             if (!dCompleted) {
289                 U32 nbLoops = 0;
290                 do {
291                     U32 blockNb;
292                     for (blockNb=0; blockNb<nbBlocks; blockNb++) {
293                         size_t const regenSize = LZ4_decompress_safe(blockTable[blockNb].cPtr, blockTable[blockNb].resPtr, (int)blockTable[blockNb].cSize, (int)blockTable[blockNb].srcSize);
294                         if (LZ4_isError(regenSize)) {
295                             DISPLAY("LZ4_decompress_safe() failed on block %u  \n", blockNb);
296                             clockLoop = 0;   /* force immediate test end */
297                             break;
298                         }
299 
300                         blockTable[blockNb].resSize = regenSize;
301                     }
302                     nbLoops++;
303                 } while (UTIL_clockSpanMicro(clockStart, ticksPerSecond) < DECOMP_MULT*clockLoop);
304                 {   U64 const clockSpan = UTIL_clockSpanMicro(clockStart, ticksPerSecond);
305                     if (clockSpan < fastestD*nbLoops) fastestD = clockSpan / nbLoops;
306                     totalDTime += clockSpan;
307                     dCompleted = totalDTime>(DECOMP_MULT*maxTime);
308             }   }
309 
310             markNb = (markNb+1) % NB_MARKS;
311             DISPLAYLEVEL(2, "%2s-%-17.17s :%10u ->%10u (%5.3f),%6.1f MB/s ,%6.1f MB/s\r",
312                     marks[markNb], displayName, (U32)srcSize, (U32)cSize, ratio,
313                     (double)srcSize / fastestC,
314                     (double)srcSize / fastestD );
315 
316             /* CRC Checking */
317             {   U64 const crcCheck = XXH64(resultBuffer, srcSize, 0);
318                 if (crcOrig!=crcCheck) {
319                     size_t u;
320                     DISPLAY("!!! WARNING !!! %14s : Invalid Checksum : %x != %x   \n", displayName, (unsigned)crcOrig, (unsigned)crcCheck);
321                     for (u=0; u<srcSize; u++) {
322                         if (((const BYTE*)srcBuffer)[u] != ((const BYTE*)resultBuffer)[u]) {
323                             U32 segNb, bNb, pos;
324                             size_t bacc = 0;
325                             DISPLAY("Decoding error at pos %u ", (U32)u);
326                             for (segNb = 0; segNb < nbBlocks; segNb++) {
327                                 if (bacc + blockTable[segNb].srcSize > u) break;
328                                 bacc += blockTable[segNb].srcSize;
329                             }
330                             pos = (U32)(u - bacc);
331                             bNb = pos / (128 KB);
332                             DISPLAY("(block %u, sub %u, pos %u) \n", segNb, bNb, pos);
333                             break;
334                         }
335                         if (u==srcSize-1) {  /* should never happen */
336                             DISPLAY("no difference detected\n");
337                     }   }
338                     break;
339             }   }   /* CRC Checking */
340 #endif
341         }   /* for (testNb = 1; testNb <= (g_nbSeconds + !g_nbSeconds); testNb++) */
342 
343         if (g_displayLevel == 1) {
344             double cSpeed = (double)srcSize / fastestC;
345             double dSpeed = (double)srcSize / fastestD;
346             if (g_additionalParam)
347                 DISPLAY("-%-3i%11i (%5.3f) %6.2f MB/s %6.1f MB/s  %s (param=%d)\n", cLevel, (int)cSize, ratio, cSpeed, dSpeed, displayName, g_additionalParam);
348             else
349                 DISPLAY("-%-3i%11i (%5.3f) %6.2f MB/s %6.1f MB/s  %s\n", cLevel, (int)cSize, ratio, cSpeed, dSpeed, displayName);
350         }
351         DISPLAYLEVEL(2, "%2i#\n", cLevel);
352     }   /* Bench */
353 
354     /* clean up */
355     free(blockTable);
356     free(compressedBuffer);
357     free(resultBuffer);
358     return 0;
359 }
360 
361 
BMK_findMaxMem(U64 requiredMem)362 static size_t BMK_findMaxMem(U64 requiredMem)
363 {
364     size_t step = 64 MB;
365     BYTE* testmem=NULL;
366 
367     requiredMem = (((requiredMem >> 26) + 1) << 26);
368     requiredMem += 2*step;
369     if (requiredMem > maxMemory) requiredMem = maxMemory;
370 
371     while (!testmem) {
372         if (requiredMem > step) requiredMem -= step;
373         else requiredMem >>= 1;
374         testmem = (BYTE*) malloc ((size_t)requiredMem);
375     }
376     free (testmem);
377 
378     /* keep some space available */
379     if (requiredMem > step) requiredMem -= step;
380     else requiredMem >>= 1;
381 
382     return (size_t)requiredMem;
383 }
384 
385 
BMK_benchCLevel(void * srcBuffer,size_t benchedSize,const char * displayName,int cLevel,int cLevelLast,const size_t * fileSizes,unsigned nbFiles)386 static void BMK_benchCLevel(void* srcBuffer, size_t benchedSize,
387                             const char* displayName, int cLevel, int cLevelLast,
388                             const size_t* fileSizes, unsigned nbFiles)
389 {
390     int l;
391 
392     const char* pch = strrchr(displayName, '\\'); /* Windows */
393     if (!pch) pch = strrchr(displayName, '/'); /* Linux */
394     if (pch) displayName = pch+1;
395 
396     SET_HIGH_PRIORITY;
397 
398     if (g_displayLevel == 1 && !g_additionalParam)
399         DISPLAY("bench %s %s: input %u bytes, %u seconds, %u KB blocks\n", LZ4_VERSION_STRING, LZ4_GIT_COMMIT_STRING, (U32)benchedSize, g_nbSeconds, (U32)(g_blockSize>>10));
400 
401     if (cLevelLast < cLevel) cLevelLast = cLevel;
402 
403     for (l=cLevel; l <= cLevelLast; l++) {
404         BMK_benchMem(srcBuffer, benchedSize,
405                      displayName, l,
406                      fileSizes, nbFiles);
407     }
408 }
409 
410 
411 /*! BMK_loadFiles() :
412     Loads `buffer` with content of files listed within `fileNamesTable`.
413     At most, fills `buffer` entirely */
BMK_loadFiles(void * buffer,size_t bufferSize,size_t * fileSizes,const char ** fileNamesTable,unsigned nbFiles)414 static void BMK_loadFiles(void* buffer, size_t bufferSize,
415                           size_t* fileSizes,
416                           const char** fileNamesTable, unsigned nbFiles)
417 {
418     size_t pos = 0, totalSize = 0;
419     unsigned n;
420     for (n=0; n<nbFiles; n++) {
421         FILE* f;
422         U64 fileSize = UTIL_getFileSize(fileNamesTable[n]);
423         if (UTIL_isDirectory(fileNamesTable[n])) {
424             DISPLAYLEVEL(2, "Ignoring %s directory...       \n", fileNamesTable[n]);
425             fileSizes[n] = 0;
426             continue;
427         }
428         f = fopen(fileNamesTable[n], "rb");
429         if (f==NULL) EXM_THROW(10, "impossible to open file %s", fileNamesTable[n]);
430         DISPLAYUPDATE(2, "Loading %s...       \r", fileNamesTable[n]);
431         if (fileSize > bufferSize-pos) fileSize = bufferSize-pos, nbFiles=n;   /* buffer too small - stop after this file */
432         { size_t const readSize = fread(((char*)buffer)+pos, 1, (size_t)fileSize, f);
433           if (readSize != (size_t)fileSize) EXM_THROW(11, "could not read %s", fileNamesTable[n]);
434           pos += readSize; }
435         fileSizes[n] = (size_t)fileSize;
436         totalSize += (size_t)fileSize;
437         fclose(f);
438     }
439 
440     if (totalSize == 0) EXM_THROW(12, "no data to bench");
441 }
442 
BMK_benchFileTable(const char ** fileNamesTable,unsigned nbFiles,int cLevel,int cLevelLast)443 static void BMK_benchFileTable(const char** fileNamesTable, unsigned nbFiles,
444                                int cLevel, int cLevelLast)
445 {
446     void* srcBuffer;
447     size_t benchedSize;
448     size_t* fileSizes = (size_t*)malloc(nbFiles * sizeof(size_t));
449     U64 const totalSizeToLoad = UTIL_getTotalFileSize(fileNamesTable, nbFiles);
450     char mfName[20] = {0};
451 
452     if (!fileSizes) EXM_THROW(12, "not enough memory for fileSizes");
453 
454     /* Memory allocation & restrictions */
455     benchedSize = BMK_findMaxMem(totalSizeToLoad * 3) / 3;
456     if (benchedSize==0) EXM_THROW(12, "not enough memory");
457     if ((U64)benchedSize > totalSizeToLoad) benchedSize = (size_t)totalSizeToLoad;
458     if (benchedSize < totalSizeToLoad)
459         DISPLAY("Not enough memory; testing %u MB only...\n", (U32)(benchedSize >> 20));
460     srcBuffer = malloc(benchedSize + !benchedSize);   /* avoid alloc of zero */
461     if (!srcBuffer) EXM_THROW(12, "not enough memory");
462 
463     /* Load input buffer */
464     BMK_loadFiles(srcBuffer, benchedSize, fileSizes, fileNamesTable, nbFiles);
465 
466     /* Bench */
467     snprintf (mfName, sizeof(mfName), " %u files", nbFiles);
468     {   const char* displayName = (nbFiles > 1) ? mfName : fileNamesTable[0];
469         BMK_benchCLevel(srcBuffer, benchedSize,
470                         displayName, cLevel, cLevelLast,
471                         fileSizes, nbFiles);
472     }
473 
474     /* clean up */
475     free(srcBuffer);
476     free(fileSizes);
477 }
478 
479 
BMK_syntheticTest(int cLevel,int cLevelLast,double compressibility)480 static void BMK_syntheticTest(int cLevel, int cLevelLast, double compressibility)
481 {
482     char name[20] = {0};
483     size_t benchedSize = 10000000;
484     void* const srcBuffer = malloc(benchedSize);
485 
486     /* Memory allocation */
487     if (!srcBuffer) EXM_THROW(21, "not enough memory");
488 
489     /* Fill input buffer */
490     RDG_genBuffer(srcBuffer, benchedSize, compressibility, 0.0, 0);
491 
492     /* Bench */
493     snprintf (name, sizeof(name), "Synthetic %2u%%", (unsigned)(compressibility*100));
494     BMK_benchCLevel(srcBuffer, benchedSize, name, cLevel, cLevelLast, &benchedSize, 1);
495 
496     /* clean up */
497     free(srcBuffer);
498 }
499 
500 
BMK_benchFiles(const char ** fileNamesTable,unsigned nbFiles,int cLevel,int cLevelLast)501 int BMK_benchFiles(const char** fileNamesTable, unsigned nbFiles,
502                    int cLevel, int cLevelLast)
503 {
504     double const compressibility = (double)g_compressibilityDefault / 100;
505 
506     if (cLevel > LZ4HC_CLEVEL_MAX) cLevel = LZ4HC_CLEVEL_MAX;
507     if (cLevelLast > LZ4HC_CLEVEL_MAX) cLevelLast = LZ4HC_CLEVEL_MAX;
508     if (cLevelLast < cLevel) cLevelLast = cLevel;
509     if (cLevelLast > cLevel) DISPLAYLEVEL(2, "Benchmarking levels from %d to %d\n", cLevel, cLevelLast);
510 
511     if (nbFiles == 0)
512         BMK_syntheticTest(cLevel, cLevelLast, compressibility);
513     else
514         BMK_benchFileTable(fileNamesTable, nbFiles, cLevel, cLevelLast);
515     return 0;
516 }
517