Change how mixed read/write workloads are done in mixedbench

Split reads and writes into separate threads, instead of mixing operations
within a single thread.  This does not allow arbitrary mixes any longer,
since the ratios are quantized based on the number of total threads.

diff --git a/microbench/mixedbench.c b/microbench/mixedbench.c
index 50dae27..0447fd1 100644 (file)
--- a/microbench/mixedbench.c
+++ b/microbench/mixedbench.c
@@ -29,6 +29,8 @@
 int opt_filesize, opt_filecount, opt_threads, opt_duration, opt_intervals, opt_dirsize;
 double opt_writeratio, opt_ops;
 
+int write_threads;
+
 struct thread_state {
     pthread_t thread;
     pthread_mutex_t lock;
@@ -93,12 +95,10 @@ void benchmark_op(struct thread_state *ts)
     char filename[256];
     int n = get_random(opt_filecount);
     int n1 = n / opt_dirsize, n2 = n % opt_dirsize;
-    sprintf(filename, "t%d/%d/%d", ts->thread_num, n1, n2);
-
-    double r = get_random(1000000) / 1e6;
 
-    if (r >= opt_writeratio) {
+    if (ts->thread_num >= write_threads) {
         /* Read */
+        sprintf(filename, "t%d/%d/%d", ts->thread_num - write_threads, n1, n2);
         FILE *f = fopen(filename, "rb");
         if (f == NULL) {
             perror("fopen");
@@ -117,6 +117,7 @@ void benchmark_op(struct thread_state *ts)
         pthread_mutex_unlock(&ts->lock);
     } else {
         /* Write */
+        sprintf(filename, "t%d/%d/%d", ts->thread_num, n1, n2);
         FILE *f = fopen(filename, "wb");
         if (f == NULL) {
             perror("fopen");
@@ -232,6 +233,12 @@ int main(int argc, char *argv[])
 
     start_time = now_hires();
 
+    /* Partition threads into those that should do reads and those for writes,
+     * as close as possible to the desired allocation. */
+    write_threads = (int)round(opt_threads * opt_writeratio);
+    fprintf(stderr, "Using %d threads for reads, %d for writes\n",
+            opt_threads - write_threads, write_threads);
+
     for (int i = 0; i < opt_threads; i++) {
         launch_thread(i);
     }