[PATCH 2/4] lib: Add igt_drop_caches_set()

[oscar.mateo@intel.com]

From: Oscar Mateo <oscar.mateo@intel.com>

This is basically a "drop cache" interface to the igt_debugfs
facilities. Also, update existing users.

Signed-off-by: Oscar Mateo <oscar.mateo@intel.com>
Cc: Damien Lespiau <damien.lespiau@intel.com>
---
 lib/igt_debugfs.c             |   28 ++++++++++++++++++++++++++++
 lib/igt_debugfs.h             |   15 +++++++++++++++
 tests/gem_persistent_relocs.c |   15 ++++-----------
 tests/gem_reloc_vs_gpu.c      |   15 ++++-----------
 4 files changed, 51 insertions(+), 22 deletions(-)

diff --git a/lib/igt_debugfs.c b/lib/igt_debugfs.c
index 0319eff..fc274fd 100644
--- a/lib/igt_debugfs.c
+++ b/lib/igt_debugfs.c
@@ -316,3 +316,31 @@ igt_pipe_crc_get_crcs(igt_pipe_crc_t *pipe_crc, int n_crcs,
 
 	*out_crcs = crcs;
 }
+
+/*
+ * Drop caches
+ */
+
+int igt_drop_caches_set(uint64_t val)
+{
+	igt_debugfs_t debugfs;
+	int fd;
+	char data[19];
+	size_t nbytes;
+	int ret = -1;
+
+	sprintf(data, "0x%" PRIx64, val);
+
+	igt_debugfs_init(&debugfs);
+	fd = igt_debugfs_open(&debugfs, "i915_gem_drop_caches", O_WRONLY);
+
+	if (fd >= 0)
+	{
+		nbytes = write(fd, data, strlen(data) + 1);
+		if (nbytes == strlen(data) + 1)
+			ret = 0;
+		close(fd);
+	}
+
+	return ret;
+}
diff --git a/lib/igt_debugfs.h b/lib/igt_debugfs.h
index c2810ee..02f4afa 100644
--- a/lib/igt_debugfs.h
+++ b/lib/igt_debugfs.h
@@ -79,4 +79,19 @@ void igt_pipe_crc_stop(igt_pipe_crc_t *pipe_crc);
 void igt_pipe_crc_get_crcs(igt_pipe_crc_t *pipe_crc, int n_crcs,
 			   igt_crc_t **out_crcs);
 
+/*
+ * Drop caches
+ */
+
+#define DROP_UNBOUND 0x1
+#define DROP_BOUND 0x2
+#define DROP_RETIRE 0x4
+#define DROP_ACTIVE 0x8
+#define DROP_ALL (DROP_UNBOUND | \
+		  DROP_BOUND | \
+		  DROP_RETIRE | \
+		  DROP_ACTIVE)
+
+int igt_drop_caches_set(uint64_t val);
+
 #endif /* __IGT_DEBUGFS_H__ */
diff --git a/tests/gem_persistent_relocs.c b/tests/gem_persistent_relocs.c
index 34d8492..863f464 100644
--- a/tests/gem_persistent_relocs.c
+++ b/tests/gem_persistent_relocs.c
@@ -42,6 +42,7 @@
 #include "intel_bufmgr.h"
 #include "intel_batchbuffer.h"
 #include "intel_gpu_tools.h"
+#include "igt_debugfs.h"
 
 /*
  * Testcase: Persistent relocations as used by uxa/libva
@@ -287,21 +288,13 @@ static void do_forked_test(int fd, unsigned flags)
 	struct igt_helper_process thrasher = {};
 
 	if (flags & (THRASH | THRASH_INACTIVE)) {
-		char fname[FILENAME_MAX];
-		int drop_caches_fd;
-		const char *data = (flags & THRASH_INACTIVE) ? "0x7" : "0xf";
-
-		snprintf(fname, FILENAME_MAX, "%s/%i/%s",
-			 "/sys/kernel/debug/dri", drm_get_card(),
-			 "i915_gem_drop_caches");
-
-		drop_caches_fd = open(fname, O_WRONLY);
-		igt_require(drop_caches_fd >= 0);
+		uint64_t val = (flags & THRASH_INACTIVE) ?
+				(DROP_RETIRE | DROP_BOUND | DROP_UNBOUND) : DROP_ALL;
 
 		igt_fork_helper(&thrasher) {
 			while (1) {
 				usleep(1000);
-				igt_assert(write(drop_caches_fd, data, strlen(data) + 1) == strlen(data) + 1);
+				do_or_die(igt_drop_caches_set(val));
 			}
 		}
 	}
diff --git a/tests/gem_reloc_vs_gpu.c b/tests/gem_reloc_vs_gpu.c
index bbfdc3a..9508b1c 100644
--- a/tests/gem_reloc_vs_gpu.c
+++ b/tests/gem_reloc_vs_gpu.c
@@ -42,6 +42,7 @@
 #include "intel_bufmgr.h"
 #include "intel_batchbuffer.h"
 #include "intel_gpu_tools.h"
+#include "igt_debugfs.h"
 
 /*
  * Testcase: Kernel relocations vs. gpu races
@@ -282,21 +283,13 @@ static void do_forked_test(int fd, unsigned flags)
 	struct igt_helper_process thrasher = {};
 
 	if (flags & (THRASH | THRASH_INACTIVE)) {
-		char fname[FILENAME_MAX];
-		int drop_caches_fd;
-		const char *data = (flags & THRASH_INACTIVE) ? "0x7" : "0xf";
-
-		snprintf(fname, FILENAME_MAX, "%s/%i/%s",
-			 "/sys/kernel/debug/dri", drm_get_card(),
-			 "i915_gem_drop_caches");
-
-		drop_caches_fd = open(fname, O_WRONLY);
-		igt_require(drop_caches_fd >= 0);
+		uint64_t val = (flags & THRASH_INACTIVE) ?
+				(DROP_RETIRE | DROP_BOUND | DROP_UNBOUND) : DROP_ALL;
 
 		igt_fork_helper(&thrasher) {
 			while (1) {
 				usleep(1000);
-				igt_assert(write(drop_caches_fd, data, strlen(data) + 1) == strlen(data) + 1);
+				do_or_die(igt_drop_caches_set(val));
 			}
 		}
 	}
-- 
1.7.9.5