add seekMap benchmark utility

benchmarks/CMakeLists.txt

@@ -38,6 +38,7 @@ CREATE_EXECUTABLE(writeBack)
 CREATE_EXECUTABLE(distributedLsnFree)
 CREATE_EXECUTABLE(bufferManager)
 CREATE_EXECUTABLE(redBlackMemoryOverhead)
+CREATE_EXECUTABLE(seekMap)
 
 IF(CHECK_LIBRARY)
   ADD_TEST(rose rose)

benchmarks/seekMap.c

@@ -0,0 +1,161 @@
+#include <config.h>
+#include <stasis/common.h>
+#include <stasis/util/time.h>
+#include <stdio.h>
+#include <math.h>
+#include <assert.h>
+
+
+uint64_t myrandom(uint64_t x) {
+  double xx = x;
+  double r = random();
+  double max = ((uint64_t)RAND_MAX)+1;
+  max /= xx;
+  return (uint64_t)((r/max));
+}
+
+void * buf;
+static void my_pread_help(int fd, long long off) {
+  int err = pread(fd, buf, 512, off);
+  if(err == -1) {
+    perror("Could not read from file");
+    abort();
+  }
+}
+
+static void drop_buffers() {
+  int fd = open("/proc/sys/vm/drop_caches", O_TRUNC|O_WRONLY);
+  if(fd == -1) { perror("Couldn't drop page cache"); abort(); }
+  char * str = "1\n";
+  int err = write(fd, str, 3);
+  if(err == -1) {
+    perror("write to drop page cache failed");
+    abort();
+  }
+  err = close(fd);
+  if(err == -1) {
+    perror("could not close file");
+    abort();
+  }
+}
+
+#define my_pread(start_off, off) my_pread_help(fd, start_off + off)
+
+int main(int argc, char * argv[]) {
+  if(argc != 7) {
+    printf("Usage: %s filename steps iterations start_off length random_mode\n", argv[0]);
+    abort();
+  }
+  posix_memalign(&buf, 512, 512);
+
+  const char * filename = argv[1];
+  int fd = open(filename, O_RDONLY);//|O_DIRECT);
+  if(fd == -1) {
+    perror("Could not open file");
+    abort();
+  }
+  int steps = atoi(argv[2]);
+  int iter  = atoi(argv[3]);
+  long length = atoll(argv[4]);
+  long start_off = atoll(argv[5]);
+  long random_mode = atoi(argv[6]);
+
+  double**  sum_x  = calloc(steps, sizeof(double*));
+  double**  sum_x2 = calloc(steps, sizeof(double*));
+  long** sample_count = calloc(steps, sizeof(long*));
+
+  for(int s = 0; s < steps; s++) {
+    sum_x[s] = calloc(steps, sizeof(double));
+    sum_x2[s] = calloc(steps, sizeof(double));
+    sample_count[s] = calloc(steps, sizeof(long));
+  }
+
+  long stride = length / steps;
+  printf("filename = %s steps = %d iter = %d length = %ld start_off = %ld stride = %ld\n",
+          filename,     steps,     iter,     length,      start_off,      stride);
+  assert(stride);
+  for(int iteration = 0; iteration < iter; iteration++) {
+    if(!random_mode || random_mode == 2) {
+      for(int xstep = 0; xstep < steps; xstep++) {
+        for(int ystep = 0; ystep < steps; ystep++) {
+          drop_buffers();
+
+          // position head (do not count the time this takes)
+          if(random_mode) {
+            my_pread(start_off, xstep * stride + myrandom(stride));
+          } else {
+            my_pread(start_off, xstep * stride);
+
+          }
+
+          struct timeval start, stop;
+          gettimeofday(&start, 0);
+          if(random_mode) {
+            my_pread(start_off, ystep * stride + myrandom(stride));
+          } else {
+            my_pread(start_off, ystep * stride);
+          }
+          gettimeofday(&stop, 0);
+
+          double elapsed = stasis_timeval_to_double(
+                             stasis_subtract_timeval(stop, start));
+          sum_x [xstep][ystep]  += elapsed;
+          sum_x2[xstep][ystep]  += elapsed*elapsed;
+        }
+        printf("%d", xstep % 10); fflush(stdout);
+      }
+    } else {
+      for(long x = 0; x < steps * steps; x++) {
+        long long start_pos = myrandom(length);
+        long long stop_pos = myrandom(length);
+
+        int xstep = start_pos / stride;
+        int ystep = stop_pos / stride;
+
+        drop_buffers();
+        // position head
+        my_pread(start_off, start_pos);
+
+        struct timeval start, stop;
+        gettimeofday(&start, 0);
+        my_pread(start_off, stop_pos);
+        gettimeofday(&stop, 0);
+
+        double elapsed = stasis_timeval_to_double(
+                           stasis_subtract_timeval(stop, start));
+        sum_x [xstep][ystep]  += elapsed;
+        sum_x2[xstep][ystep]  += elapsed*elapsed;
+        sample_count[xstep][ystep] ++;
+
+      }
+    }
+    printf("\nIteration %d mean seek time:\n", iteration);
+    for(int xstep = 0; xstep < steps; xstep++) {
+      for(int ystep = 0; ystep < steps; ystep++) {
+        double n = (double) random_mode==1
+            ?(sample_count[xstep][ystep]
+               ?sample_count[xstep][ystep]
+               :1)
+            :(iteration+1);
+        printf("%f%s", sum_x[xstep][ystep] / n,
+                       (ystep==steps-1)?"\n":"\t");
+      }
+    }
+    printf("\nIteration %d stddev seek time:\n", iteration);
+    for(int xstep = 0; xstep < steps; xstep++) {
+      for(int ystep = 0; ystep < steps; ystep++) {
+        double n = (double) random_mode==1
+            ?(sample_count[xstep][ystep]
+               ?sample_count[xstep][ystep]
+               :1)
+            :(iteration+1);
+        double mean = sum_x[xstep][ystep]/n;
+        printf("%f%s", sqrt(sum_x2[xstep][ystep]/n - mean*mean),
+                       (ystep==steps-1)?"\n":"\t");
+      }
+    }
+    fflush(stdout);
+  }
+  close(fd);
+  return 0;
+}