Changeset d22e567 in mainline

Timestamp:

2012-12-04T21:11:02Z (11 years ago)

Author:

Adam Hraska <adam.hraska+hos@…>

Branches:

lfn, master, serial, ticket/834-toolchain-update, topic/msim-upgrade, topic/simplify-dev-export

Children:

6a585dd

Parents:

f74ec77

Message:

rcubench: Replaced futex contention benchmark with futex syscall benchmark.

File:

• uspace/app/rcubench/rcubench.c (modified) (4 diffs)

uspace/app/rcubench/rcubench.c

@@ -67 +67 @@
 
 
-/* Combats compiler optimizations. */
-static volatile size_t dummy = 0;
-
-static size_t sum_array(size_t *array, size_t len)
-{
-        size_t sum = 0;
-        
-        for (size_t k = 0; k < len; ++k)
-                sum += array[k];
-        
-        return sum;
-}
 
 
 static void  kernel_futex_bench(bench_t *bench)
 {
-        futex_t * const fut = &bench->bench_fut;
         const size_t iters = bench->iters;
-        size_t sum = 0;
         
         for (size_t i = 0; i < iters; ++i) {
-                /* Do some work with the futex locked to encourage contention. */
-                futex_down(fut);
-                sum += sum_array(bench->array, bench->array_size);
-                futex_up(fut);
-                
-                /* 
-                 * Do half as much work to give other threads a chance to acquire 
-                 * the futex.
-                 */
-                sum += sum_array(bench->array, bench->array_size / 2);
-        }
-        
-        /* 
-         * Writing to a global volatile variable separated with a cc-barrier
-         * should discourage the compiler from optimizing away sum_array()s.
-         */
-        compiler_barrier();
-        dummy = sum;
+                int val = 0;
+                __SYSCALL1(SYS_FUTEX_WAKEUP, (sysarg_t) &val);
+                __SYSCALL1(SYS_FUTEX_SLEEP, (sysarg_t) &val);
+        }
 }
 
@@ -179 +151 @@
 }
 
-static const char *results_txt = "/tmp/rcu-bench-results.txt";
+static const char *results_txt = "/tmp/urcu-bench-results.txt";
 
 static bool open_results(void)
@@ -211 +183 @@
         printf("rcubench [test-name] [k-iterations] [n-threads] {work-size}\n");
         printf("Available tests: \n");
-        printf("  ke-futex .. threads down/up a shared futex and do some work when\n");
-        printf("              in critical section; do a little less work outside CS.\n");
+        printf("  sys-futex.. threads make wakeup/sleepdown futex syscalls in a loop\n");
+        printf("              but for separate variables/futex kernel objects.\n");
         printf("  lock     .. threads lock/unlock separate futexes.\n");
         printf("  sema     .. threads down/up separate futexes.\n");
@@ -232 +204 @@
         futex_initialize(&bench->bench_fut, 1);
         
-        if (0 == str_cmp(argv[1], "ke-futex")) {
+        if (0 == str_cmp(argv[1], "sys-futex")) {
                 bench->func = kernel_futex_bench;
         } else if (0 == str_cmp(argv[1], "lock")) {