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, 20 insertions, 0 deletions

diff --git a/test/util/fs_util.cc b/test/util/fs_util.cc
index f7d231b14..88b1e7911 100644
--- a/test/util/fs_util.cc
+++ b/test/util/fs_util.cc
@@ -163,6 +163,26 @@ PosixError Chmod(absl::string_view path, int mode) {
   return NoError();
 }
 
+PosixError MknodAt(const FileDescriptor& dfd, absl::string_view path, int mode,
+                   dev_t dev) {
+  int res = mknodat(dfd.get(), std::string(path).c_str(), mode, dev);
+  if (res < 0) {
+    return PosixError(errno, absl::StrCat("mknod ", path));
+  }
+
+  return NoError();
+}
+
+PosixError UnlinkAt(const FileDescriptor& dfd, absl::string_view path,
+                    int flags) {
+  int res = unlinkat(dfd.get(), std::string(path).c_str(), flags);
+  if (res < 0) {
+    return PosixError(errno, absl::StrCat("unlink ", path));
+  }
+
+  return NoError();
+}
+
 PosixError Mkdir(absl::string_view path, int mode) {
   int res = mkdir(std::string(path).c_str(), mode);
   if (res < 0) {