src: make --use-largepages a three-valued option

Author: Gabriel Schulhof

doc/api/cli.md

@@ -863,7 +863,7 @@ environment variables.
 
 See `SSL_CERT_DIR` and `SSL_CERT_FILE`.
 
-### `--use-largepages`
+### `--use-largepages=num`
 <!-- YAML
 added: REPLACEME
 -->
@@ -872,6 +872,13 @@ Re-map the Node.js static code to large memory pages at startup. If supported on
 the target system, this will cause the Node.js static code to be moved onto 2
 MiB pages instead of 4 KiB pages.
 
+The following values are valid for `num`:
+* 0: No mapping will be attempted. This is the default.
+* 1: If supported by the OS, mapping will be attempted. Failure to map will be
+  ignored and will not be reported.
+* 2: If supported by the OS, mapping will be attempted. Failure to map will be
+  ignored and a message will be printed to standard error.
+
 ### `--v8-options`
 <!-- YAML
 added: v0.1.3

doc/node.1

@@ -398,10 +398,12 @@ See
 and
 .Ev SSL_CERT_FILE .
 .
-.It Fl -use-largepages
+.It Fl -use-largepages Ns = Ns Ar num
 Re-map the Node.js static code to large memory pages at startup. If supported on
 the target system, this will cause the Node.js static code to be moved onto 2
 MiB pages instead of 4 KiB pages.
+.Pp
+The following values are valid: 0 (do not map), 1 (map, ignore failure, and do not report it), and 2 (map, ignore failure, but report it to standard error).
 .
 .It Fl -v8-options
 Print V8 command-line options.

src/node.cc

@@ -984,9 +984,11 @@ InitializationResult InitializeOncePerProcess(int argc, char** argv) {
     }
   }
 
-  if (per_process::cli_options->use_largepages) {
+  if (per_process::cli_options->use_largepages == 1 ||
+      per_process::cli_options->use_largepages == 2) {
     if (node::IsLargePagesEnabled()) {
-      if (node::MapStaticCodeToLargePages() != 0) {
+      if (node::MapStaticCodeToLargePages() != 0 &&
+          per_process::cli_options->use_largepages == 2) {
         fprintf(stderr, "Reverting to default page size\n");
       }
     }

src/node_options.cc

@@ -63,6 +63,9 @@ void PerProcessOptions::CheckOptions(std::vector<std::string>* errors) {
                       "used, not both");
   }
 #endif
+  if (!(use_largepages >= 0 && use_largepages <= 2)) {
+    errors->push_back("--use-largepages must be one of 0, 1, or 2");
+  }
   per_isolate->CheckOptions(errors);
 }
 

src/node_options.h

@@ -235,7 +235,7 @@ class PerProcessOptions : public Options {
   bool force_fips_crypto = false;
 #endif
 #endif
-  bool use_largepages = false;
+  uint64_t use_largepages = 0;
 
 #ifdef NODE_REPORT
   std::vector<std::string> cmdline;