allow jobSize to be as low as 512 KB

previous lower limit was 1 MB.

Note : by default, the lowest job size is 2 MB, achieved at level 1.
Even lower job sizes can be achieved by manipulating this value directly,
or manually modifying window sizes to lower amounts.

Updated unit test to ensure that this new limit works fine
(test would fail with previous 1 MB limit).

diff --git a/lib/compress/zstdmt_compress.h b/lib/compress/zstdmt_compress.h
index 3b4c14f0e43cc6c90142876f958f3c7d54a4c348..3d9614a7eb905c7dfcf8ddd76c24be19d742e759 100644 (file)
--- a/lib/compress/zstdmt_compress.h
+++ b/lib/compress/zstdmt_compress.h
@@ -32,11 +32,11 @@
 
 
 /* ===   Constants   === */
-#ifndef ZSTDMT_NBWORKERS_MAX
+#ifndef ZSTDMT_NBWORKERS_MAX   /* can be modified at compile time */
 #  define ZSTDMT_NBWORKERS_MAX 200
 #endif
-#ifndef ZSTDMT_JOBSIZE_MIN
-#  define ZSTDMT_JOBSIZE_MIN (1 MB)
+#ifndef ZSTDMT_JOBSIZE_MIN   /* can be modified at compile time */
+#  define ZSTDMT_JOBSIZE_MIN (512 KB)
 #endif
 #define ZSTDMT_JOBLOG_MAX   (MEM_32bits() ? 29 : 30)
 #define ZSTDMT_JOBSIZE_MAX  (MEM_32bits() ? (512 MB) : (1024 MB))

diff --git a/tests/fuzzer.c b/tests/fuzzer.c
index 1b1042393ceb29f9ef3977270ec1f95b0b8da043..2c6c60d3833372b44aecf7bc50974022b0c32e51 100644 (file)
--- a/tests/fuzzer.c
+++ b/tests/fuzzer.c
@@ -1589,6 +1589,7 @@ static int basicUnitTests(U32 const seed, double compressibility)
 
     DISPLAYLEVEL(3, "test%3i : setting multithreaded parameters : ", testNb++)
     {   ZSTD_CCtx_params* params = ZSTD_createCCtxParams();
+        int const jobSize = 512 KB;
         int value;
         /* Check that the overlap log and job size are unset. */
         CHECK( ZSTD_CCtxParams_getParameter(params, ZSTD_c_overlapLog, &value) );
@@ -1597,19 +1598,18 @@ static int basicUnitTests(U32 const seed, double compressibility)
         CHECK_EQ(value, 0);
         /* Set and check the overlap log and job size. */
         CHECK( ZSTD_CCtxParams_setParameter(params, ZSTD_c_overlapLog, 5) );
-        CHECK( ZSTD_CCtxParams_setParameter(params, ZSTD_c_jobSize, 2 MB) );
+        CHECK( ZSTD_CCtxParams_setParameter(params, ZSTD_c_jobSize, jobSize) );
         CHECK( ZSTD_CCtxParams_getParameter(params, ZSTD_c_overlapLog, &value) );
         CHECK_EQ(value, 5);
         CHECK( ZSTD_CCtxParams_getParameter(params, ZSTD_c_jobSize, &value) );
-        CHECK_EQ(value, 2 MB);
+        CHECK_EQ(value, jobSize);
         /* Set the number of workers and check the overlap log and job size. */
         CHECK( ZSTD_CCtxParams_setParameter(params, ZSTD_c_nbWorkers, 2) );
         CHECK( ZSTD_CCtxParams_getParameter(params, ZSTD_c_overlapLog, &value) );
         CHECK_EQ(value, 5);
         CHECK( ZSTD_CCtxParams_getParameter(params, ZSTD_c_jobSize, &value) );
-        CHECK_EQ(value, 2 MB);
+        CHECK_EQ(value, jobSize);
         ZSTD_freeCCtxParams(params);
-
     }
     DISPLAYLEVEL(3, "OK \n");