igt/gem_mmap_gtt/wc: Reduce test runtime

Add a new iterator macro to run for a specified number of milliseconds.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>

2 files changed, 21 insertions, 8 deletions

diff --git a/lib/igt_aux.h b/lib/igt_aux.h
index 5627cb04..7f5a7cfd 100644
--- a/lib/igt_aux.h
+++ b/lib/igt_aux.h
@@ -85,6 +85,19 @@ bool __igt_sigiter_continue(struct __igt_sigiter *iter, bool interrupt);
 #define igt_until_timeout(timeout) \
 	for (struct timespec t__={}; igt_seconds_elapsed(&t__) < (timeout); )
 
+/**
+ * igt_for_milliseconds:
+ * @time: how long to run the loop in milliseconds
+ *
+ * Convenience macro loop to run the provided code block in a loop until the
+ * target interval has expired. Of course when an individual execution takes
+ * too long, the actual execution time could be a lot longer.
+ *
+ * The code block will be executed at least once.
+ */
+#define igt_for_milliseconds(t) \
+	for (struct timespec t__={}; igt_nsec_elapsed(&t__)>>20 < (t); )
+
 void igt_exchange_int(void *array, unsigned i, unsigned j);
 void igt_permute_array(void *array, unsigned size,
 			   void (*exchange_func)(void *array,
diff --git a/tests/gem_mmap_gtt.c b/tests/gem_mmap_gtt.c
index ef41bcc0..60034df3 100644
--- a/tests/gem_mmap_gtt.c
+++ b/tests/gem_mmap_gtt.c
@@ -248,26 +248,26 @@ test_wc(int fd)
 	gem_close(fd, handle);
 
 	gtt_reads = 0;
-	igt_until_timeout(1) {
+	igt_for_milliseconds(200) {
 		memcpy(cpu, gtt, 4096);
 		gtt_reads++;
 	}
-	igt_debug("%lu GTT reads in 1s\n", gtt_reads);
+	igt_debug("%lu GTT reads in 200us\n", gtt_reads);
 
 	gtt_writes = 0;
-	igt_until_timeout(1) {
+	igt_for_milliseconds(200) {
 		memcpy(gtt, cpu, 4096);
 		gtt_writes++;
 	}
-	igt_debug("%lu GTT writes in 1s\n", gtt_writes);
+	igt_debug("%lu GTT writes in 200us\n", gtt_writes);
 
 	if (igt_setup_clflush()) {
 		cpu_writes = 0;
-		igt_until_timeout(1) {
+		igt_for_milliseconds(200) {
 			igt_clflush_range(cpu, 4096);
 			cpu_writes++;
 		}
-		igt_debug("%lu CPU writes in 1s\n", cpu_writes);
+		igt_debug("%lu CPU writes in 200us\n", cpu_writes);
 	} else
 		cpu_writes = gtt_writes;
 
@@ -276,11 +276,11 @@ test_wc(int fd)
 
 	igt_assert_f(gtt_writes > 2*gtt_reads,
 		     "Write-Combined writes are expected to be much faster than reads: read=%.2fMiB/s, write=%.2fMiB/s\n",
-		     gtt_reads/256., gtt_writes/256.);
+		     5*gtt_reads/256., 5*gtt_writes/256.);
 
 	igt_assert_f(gtt_writes > cpu_writes/2,
 		     "Write-Combined writes are expected to be roughly equivalent to WB writes: WC (gtt)=%.2fMiB/s, WB (cpu)=%.2fMiB/s\n",
-		     gtt_writes/256., cpu_writes/256.);
+		     5*gtt_writes/256., 5*cpu_writes/256.);
 }
 
 static void