test size was wrong in 'fillbatch' benchmark (#5198)

Summary:
for fillbatch benchmar, the numEntries should be [num_] but not [num_ / 1000] because numEntries is just the total entries we want to test
Pull Request resolved: https://github.com/facebook/rocksdb/pull/5198

Differential Revision: D17274664

Pulled By: anand1976

fbshipit-source-id: f96e952babdbac63fb99d14e1254d478a10437be

java/benchmark/src/main/java/org/rocksdb/benchmark/DbBenchmark.java

@@ -646,8 +646,8 @@ public class DbBenchmark {
               currentTaskId++, randSeed_, num_, num_, writeOpt, 1));
           break;
         case "fillbatch":
-          tasks.add(new WriteRandomTask(
-              currentTaskId++, randSeed_, num_ / 1000, num_, writeOpt, 1000));
+          tasks.add(new WriteSequentialTask(
+              currentTaskId++, randSeed_, num_, num_, writeOpt, 1000));
           break;
         case "fillrandom":
           tasks.add(new WriteRandomTask(
@@ -911,7 +911,7 @@ public class DbBenchmark {
         "\t\tfillseq          -- write N values in sequential key order in async mode.\n" +
         "\t\tfillrandom       -- write N values in random key order in async mode.\n" +
         "\t\tfillbatch        -- write N/1000 batch where each batch has 1000 values\n" +
-        "\t\t                   in random key order in sync mode.\n" +
+        "\t\t                   in sequential key order in sync mode.\n" +
         "\t\tfillsync         -- write N/100 values in random key order in sync mode.\n" +
         "\t\tfill100K         -- write N/1000 100K values in random order in async mode.\n" +
         "\t\treadseq          -- read N times sequentially.\n" +