relax passing conditions for dispatch_concur

Further relax the expected minimum level of concurrency
when running on a multi-CPU system to only require that
we observe at least 50% of the potential concurrency is
actually realized.  This should be loose enough to avoid
spurious failures when run in the CI environment while
still being able to detect when we are very badly missing
the expected levels of concurrency.

Author: dgrove-oss

tests/dispatch_concur.c

@@ -32,7 +32,7 @@
 static volatile size_t done, concur;
 static int use_group_async;
 static uint32_t activecpu;
-static int32_t xfail = 0;
+static uint32_t min_acceptable_concurrency;
 
 static dispatch_queue_t q;
 static dispatch_group_t g, gw;
@@ -96,8 +96,8 @@ test_concur_async(size_t n, size_t qw)
 
 	if (qw > 1) {
 		size_t concurrency = MIN(n * workers, qw);
-		if (concurrency > done && done >= activecpu) {
-			xfail++;
+		if (done > min_acceptable_concurrency) {
+			test_long_less_than_or_equal("concurrently completed workers", done, concurrency);
 		} else {
 			test_long("concurrently completed workers", done, concurrency);
 		}
@@ -111,8 +111,8 @@ test_concur_async(size_t n, size_t qw)
 	free(mcs);
 
 	size_t expect = MIN(n, qw);
-	if (expect > max_concur && max_concur >= activecpu) {
-		xfail++;
+	if (max_concur > min_acceptable_concurrency) {
+		test_long_less_than_or_equal("max submission concurrency", max_concur, expect);
 	} else {
 		test_long("max submission concurrency", max_concur, expect);
 	}
@@ -154,8 +154,8 @@ test_concur_sync(size_t n, size_t qw)
 	free(mcs);
 
 	size_t expect = qw == 1 ? 1 : n;
-	if (expect > max_concur && max_concur >= activecpu) {
-		xfail++;
+	if (max_concur > min_acceptable_concurrency) {
+		test_long_less_than_or_equal("max sync concurrency", max_concur, expect);
 	} else {
 		test_long("max sync concurrency", max_concur, expect);
 	}
@@ -185,8 +185,8 @@ test_concur_apply(size_t n, size_t qw)
 	free(mcs);
 
 	size_t expect = MIN(n, qw);
-	if (expect > max_concur && max_concur >= activecpu) {
-		xfail++;
+	if (max_concur > min_acceptable_concurrency) {
+		test_long_less_than_or_equal("max apply concurrency", max_concur, expect);
 	} else {
 		test_long("max apply concurrency", max_concur, expect);
 	}
@@ -233,6 +233,7 @@ main(int argc __attribute__((unused)), char* argv[] __attribute__((unused)))
 	sysctlbyname("hw.activecpu", &activecpu, &s, NULL, 0);
 #endif
 	size_t n = activecpu / 2 > 1 ? activecpu / 2 : 1, w = activecpu * 2;
+	min_acceptable_concurrency = n;
 	dispatch_queue_t tq, ttq;
 	long qw, tqw, ttqw;
 	const char *ql, *tql, *ttql;
@@ -274,8 +275,6 @@ main(int argc __attribute__((unused)), char* argv[] __attribute__((unused)))
 		dispatch_release(ttq);
 	}
 
-	test_long_less_than_or_equal("6 failures for this test is acceptable", xfail, 6);
-
 	dispatch_release(g);
 	dispatch_release(gw);