test/perf: optimize the getdents test

* Use mknod instead of open&close to create an empty file.
* Limit a number of files to (1<<16) instead of 100K.

In this case, a test set is (1, 8, 64, 512, 4K, 32K, 64K) instead of (1, 8, 64,
512, 4K, 32K, 98K). I think it is easier to compare results for 32K and 64K
than 32K and 98K. And results for 98K doesn't give us more information than for
54K.

PiperOrigin-RevId: 275552507

1 files changed, 9 insertions, 0 deletions

diff --git a/test/util/fs_util.h b/test/util/fs_util.h
index e5b555891..ee1b341d7 100644
--- a/test/util/fs_util.h
+++ b/test/util/fs_util.h
@@ -21,6 +21,7 @@
 #include <unistd.h>
 
 #include "absl/strings/string_view.h"
+#include "test/util/file_descriptor.h"
 #include "test/util/posix_error.h"
 
 namespace gvisor {
@@ -44,6 +45,14 @@ PosixError Delete(absl::string_view path);
 // Changes the mode of a file or returns an error.
 PosixError Chmod(absl::string_view path, int mode);
 
+// Create a special or ordinary file.
+PosixError MknodAt(const FileDescriptor& dfd, absl::string_view path, int mode,
+                   dev_t dev);
+
+// Unlink the file.
+PosixError UnlinkAt(const FileDescriptor& dfd, absl::string_view path,
+                    int flags);
+
 // Truncates a file to the given length or returns an error.
 PosixError Truncate(absl::string_view path, int length);