Set --seed per test

Summary:
This is done to avoid having each thread use the same seed between runs
of db_bench. Without this we can inflate the OS filesystem cache hit rate on
reads for read heavy tests and generally see the same key sequences get generated
between teste runs.

Task ID: #

Blame Rev:

Test Plan:
Revert Plan:

Database Impact:

Memcache Impact:

Other Notes:

EImportant:

- begin *PUBLIC* platform impact section -
Bugzilla: #
- end platform impact -

Reviewers: igor

Reviewed By: igor

Subscribers: dhruba

Differential Revision: https://reviews.facebook.net/D37563

tools/benchmark.sh

@@ -138,6 +138,7 @@ function run_bulkload {
        --threads=1 \
        --memtablerep=vector \
        --disable_wal=1 \
+       --seed=$( date +%s ) \
        2>&1 | tee -a $output_dir/benchmark_bulkload_fillrandom.log"
   echo $cmd | tee $output_dir/benchmark_bulkload_fillrandom.log
   eval $cmd
@@ -166,6 +167,7 @@ function run_fillseq {
        --threads=1 \
        --memtablerep=vector \
        --disable_wal=1 \
+       --seed=$( date +%s ) \
        2>&1 | tee -a $output_dir/benchmark_fillseq.v${value_size}.log"
   echo $cmd | tee $output_dir/benchmark_fillseq.v${value_size}.log
   eval $cmd
@@ -182,6 +184,7 @@ function run_change {
        $params_w \
        --threads=$num_threads \
        --merge_operator=\"put\" \
+       --seed=$( date +%s ) \
        2>&1 | tee -a $output_dir/${out_name}"
   echo $cmd | tee $output_dir/${out_name}
   eval $cmd
@@ -195,6 +198,7 @@ function run_filluniquerandom {
        --sync=0 \
        $params_w \
        --threads=1 \
+       --seed=$( date +%s ) \
        2>&1 | tee -a $output_dir/benchmark_filluniquerandom.log"
   echo $cmd | tee $output_dir/benchmark_filluniquerandom.log
   eval $cmd
@@ -208,6 +212,7 @@ function run_readrandom {
        --use_existing_db=1 \
        $params_w \
        --threads=$num_threads \
+       --seed=$( date +%s ) \
        2>&1 | tee -a $output_dir/${out_name}"
   echo $cmd | tee $output_dir/${out_name}
   eval $cmd
@@ -225,6 +230,7 @@ function run_readwhile {
        --threads=$num_threads \
        --writes_per_second=$writes_per_second \
        --merge_operator=\"put\" \
+       --seed=$( date +%s ) \
        2>&1 | tee -a $output_dir/${out_name}"
   echo $cmd | tee $output_dir/${out_name}
   eval $cmd
@@ -246,6 +252,7 @@ function run_rangewhile {
        --merge_operator=\"put\" \
        --seek_nexts=$num_nexts_per_seek \
        --reverse_iterator=$reverse_arg \
+       --seed=$( date +%s ) \
        2>&1 | tee -a $output_dir/${out_name}"
   echo $cmd | tee $output_dir/${out_name}
   eval $cmd
@@ -263,6 +270,7 @@ function run_range {
        --threads=$num_threads \
        --seek_nexts=$num_nexts_per_seek \
        --reverse_iterator=$reverse_arg \
+       --seed=$( date +%s ) \
        2>&1 | tee -a $output_dir/${out_name}"
   echo $cmd | tee $output_dir/${out_name}
   eval $cmd