[igt-dev] [PATCH i-g-t v3 2/2] igt/evictions: Avoid getting killed by the reaper in mlock

[Michał Winiarski]

We're little bit too enthusiastic in our initial attempt to lock all
available memory. Let's use the mlock probe from lib rather than trying
to lock everything that sysinfo.freeram has to offer.
Note that we're only tweaking the initial step - it's still possible
that we're going to get killed later on.

v2: Just increment lock instead of modifying addr passed to mlock

Signed-off-by: Michał Winiarski <michal.winiarski at intel.com>
Cc: Chris Wilson <chris at chris-wilson.co.uk>
Cc: Ewelina Musial <ewelina.musial at intel.com>
Reviewed-by: Chris Wilson <chris at chris-wilson.co.uk>
---
 tests/eviction_common.c | 54 ++++++++++++++++-------------------------
 1 file changed, 21 insertions(+), 33 deletions(-)

diff --git a/tests/eviction_common.c b/tests/eviction_common.c
index 300eb03d..8535dfca 100644
--- a/tests/eviction_common.c
+++ b/tests/eviction_common.c
@@ -133,47 +133,33 @@ static void mlocked_evictions(int fd, struct igt_eviction_test_ops *ops,
 			      uint64_t surface_size,
 			      uint64_t surface_count)
 {
-	unsigned int *can_mlock;
-	uint64_t sz, pin;
+	void *mem;
+	uint64_t sz, pin_total;
 
 	intel_require_memory(surface_count, surface_size, CHECK_RAM);
 
 	sz = surface_size*surface_count;
-	pin = intel_get_avail_ram_mb();
-	pin *= 1024 * 1024;
-	igt_require(pin > sz);
-	pin -= sz;
+	pin_total = intel_get_total_pinnable_mem();
+	igt_require(pin_total > sz);
 
-	igt_debug("Pinning [%'lld, %'lld] MiB\n",
-		  (long long)pin/(1024*1024),
-		  (long long)(pin + sz)/(1024*1024));
-
-	can_mlock = mmap(NULL, 4096, PROT_WRITE, MAP_SHARED | MAP_ANON, -1, 0);
-	igt_assert(can_mlock != MAP_FAILED);
+	mem = mmap(NULL, pin_total, PROT_READ, MAP_SHARED | MAP_ANON, -1, 0);
+	igt_assert(mem != MAP_FAILED);
 
 	igt_fork(child, 1) {
-		void *locked;
-
-		locked = malloc(pin + sz);
-		if (locked != NULL && !mlock(locked, pin + sz))
-			*can_mlock = 1;
-	}
-	igt_waitchildren();
-	igt_require(*can_mlock);
-	munmap(can_mlock, 4096);
-
-	igt_fork(child, 1) {
-		void *locked;
 		uint32_t *bo;
 		uint64_t n;
 		int ret;
+		size_t lock = pin_total - sz;
 
-		bo = malloc(surface_count*sizeof(*bo));
+		bo = malloc(surface_count * sizeof(*bo));
 		igt_assert(bo);
+		lock -= ALIGN(surface_count * sizeof(*bo), 4096);
 
-		locked = malloc(pin);
-		if (locked == NULL || mlock(locked, pin))
-			exit(ENOSPC);
+		igt_debug("Locking %'"PRIu64" B (%'"PRIu64" MiB)\n",
+			  lock, lock >> 20);
+		igt_assert(!mlock(mem, lock));
+		igt_info("Locked %'"PRIu64" B (%'"PRIu64" MiB)\n",
+			 lock, lock >> 20);
 
 		for (n = 0; n < surface_count; n++)
 			bo[n] = ops->create(fd, surface_size);
@@ -188,17 +174,19 @@ static void mlocked_evictions(int fd, struct igt_eviction_test_ops *ops,
 			 * our pages into memory), start a memory hog to
 			 * force evictions.
 			 */
-
-			locked = malloc(surface_size);
-			if (locked == NULL || mlock(locked, surface_size))
-				free(locked);
+			lock += surface_size;
+			igt_assert(!mlock(mem, lock));
+			igt_debug("Total locked %'"PRIu64" B (%'"PRIu64" MiB)\n",
+				  lock,
+				  lock >> 20);
 		}
 
 		for (n = 0; n < surface_count; n++)
 			ops->close(fd, bo[n]);
 	}
-
 	igt_waitchildren();
+
+	munmap(mem, pin_total);
 }
 
 static int swapping_evictions(int fd, struct igt_eviction_test_ops *ops,
-- 
2.17.1