src: make --use-largepages a runtime option

Moves the option that instructs Node.js to-remap its static code to
large pages from a configure-time option to a runtime option. This
should make it easy to assess the performance impact of such a change
without having to custom-build.

Author: Gabriel Schulhof

configure.py

@@ -404,17 +404,6 @@
     dest='with_etw',
     help='build with ETW (default is true on Windows)')
 
-parser.add_option('--use-largepages',
-    action='store_true',
-    dest='node_use_large_pages',
-    help='build with Large Pages support. This feature is supported only on Linux kernel' +
-         '>= 2.6.38 with Transparent Huge pages enabled and FreeBSD')
-
-parser.add_option('--use-largepages-script-lld',
-    action='store_true',
-    dest='node_use_large_pages_script_lld',
-    help='link against the LLVM ld linker script. Implies -fuse-ld=lld in the linker flags')
-
 intl_optgroup.add_option('--with-intl',
     action='store',
     dest='with_intl',
@@ -1068,28 +1057,6 @@ def configure_node(o):
   else:
     o['variables']['node_use_dtrace'] = 'false'
 
-  if options.node_use_large_pages and not flavor in ('linux', 'freebsd', 'mac'):
-    raise Exception(
-      'Large pages are supported only on Linux, FreeBSD and MacOS Systems.')
-  if options.node_use_large_pages and flavor in ('linux', 'freebsd', 'mac'):
-    if options.shared or options.enable_static:
-      raise Exception(
-        'Large pages are supported only while creating node executable.')
-    if target_arch!="x64":
-      raise Exception(
-        'Large pages are supported only x64 platform.')
-    if flavor == 'mac':
-      info('macOS server with 32GB or more is recommended')
-    if flavor == 'linux':
-      # Example full version string: 2.6.32-696.28.1.el6.x86_64
-      FULL_KERNEL_VERSION=os.uname()[2]
-      KERNEL_VERSION=FULL_KERNEL_VERSION.split('-')[0]
-      if KERNEL_VERSION < "2.6.38" and flavor == 'linux':
-        raise Exception(
-          'Large pages need Linux kernel version >= 2.6.38')
-  o['variables']['node_use_large_pages'] = b(options.node_use_large_pages)
-  o['variables']['node_use_large_pages_script_lld'] = b(options.node_use_large_pages_script_lld)
-
   if options.no_ifaddrs:
     o['defines'] += ['SUNOS_NO_IFADDRS']
 

doc/api/cli.md

@@ -863,6 +863,15 @@ environment variables.
 
 See `SSL_CERT_DIR` and `SSL_CERT_FILE`.
 
+### `--use-largepages`
+<!-- YAML
+added: REPLACEME
+-->
+
+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.
+
 ### `--v8-options`
 <!-- YAML
 added: v0.1.3
@@ -1119,6 +1128,7 @@ Node.js options that are allowed are:
 * `--track-heap-objects`
 * `--unhandled-rejections`
 * `--use-bundled-ca`
+* `--use-largepages`
 * `--use-openssl-ca`
 * `--v8-pool-size`
 * `--zero-fill-buffers`

doc/node.1

@@ -398,6 +398,11 @@ See
 and
 .Ev SSL_CERT_FILE .
 .
+.It Fl -use-largepages
+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.
+.
 .It Fl -v8-options
 Print V8 command-line options.
 .

node.gyp

@@ -833,7 +833,7 @@
             }],
           ],
         }],
-        [ 'node_use_large_pages=="true" and OS in "linux freebsd mac"', {
+        [ 'OS in "linux freebsd mac"', {
           'defines': [ 'NODE_ENABLE_LARGE_CODE_PAGES=1' ],
           # The current implementation of Large Pages is under Linux.
           # Other implementations are possible but not currently supported.

node.gypi

@@ -308,17 +308,15 @@
     }],
     [ 'OS=="linux" and '
       'target_arch=="x64" and '
-      'node_use_large_pages=="true" and '
-      'node_use_large_pages_script_lld=="false"', {
+      'llvm_version=="0.0"', {
       'ldflags': [
         '-Wl,-T',
         '<!(realpath src/large_pages/ld.implicit.script)',
       ]
     }],
     [ 'OS=="linux" and '
       'target_arch=="x64" and '
-      'node_use_large_pages=="true" and '
-      'node_use_large_pages_script_lld=="true"', {
+      'llvm_version!="0.0"', {
       'ldflags': [
         '-Wl,-T',
         '<!(realpath src/large_pages/ld.implicit.script.lld)',

src/large_pages/node_large_page.cc

@@ -62,7 +62,7 @@
 // Map a new area and copy the original code there
 // Use mmap using the start address with MAP_FIXED so we get exactly the
 // same virtual address
-// Use madvise with MADV_HUGE_PAGE to use Anonymous 2M Pages
+// Use madvise with MADV_HUGEPAGE to use Anonymous 2M Pages
 // If successful copy the code there and unmap the original region.
 
 extern char __nodetext;
@@ -308,7 +308,7 @@ static bool IsSuperPagesEnabled() {
 // a. map a new area and copy the original code there
 // b. mmap using the start address with MAP_FIXED so we get exactly
 //    the same virtual address (except on macOS).
-// c. madvise with MADV_HUGE_PAGE
+// c. madvise with MADV_HUGEPAGE
 // d. If successful copy the code there and unmap the original region
 int
 #if !defined(__APPLE__)
@@ -352,7 +352,7 @@ MoveTextRegionToLargePages(const text_region& r) {
     return -1;
   }
 
-  ret = madvise(tmem, size, MADV_HUGEPAGE);
+  ret = madvise(tmem, size, 14 /* MADV_HUGEPAGE */);
   if (ret == -1) {
     PrintSystemError(errno);
     ret = munmap(tmem, size);

src/node.cc

@@ -64,9 +64,7 @@
 #include "inspector/worker_inspector.h"  // ParentInspectorHandle
 #endif
 
-#ifdef NODE_ENABLE_LARGE_CODE_PAGES
 #include "large_pages/node_large_page.h"
-#endif
 
 #ifdef NODE_REPORT
 #include "node_report.h"
@@ -967,14 +965,6 @@ InitializationResult InitializeOncePerProcess(int argc, char** argv) {
 
   CHECK_GT(argc, 0);
 
-#ifdef NODE_ENABLE_LARGE_CODE_PAGES
-  if (node::IsLargePagesEnabled()) {
-    if (node::MapStaticCodeToLargePages() != 0) {
-      fprintf(stderr, "Reverting to default page size\n");
-    }
-  }
-#endif
-
   // Hack around with the argv pointer. Used for process.title = "blah".
   argv = uv_setup_args(argc, argv);
 
@@ -994,6 +984,14 @@ InitializationResult InitializeOncePerProcess(int argc, char** argv) {
     }
   }
 
+  if (per_process::cli_options->use_largepages) {
+    if (node::IsLargePagesEnabled()) {
+      if (node::MapStaticCodeToLargePages() != 0) {
+        fprintf(stderr, "Reverting to default page size\n");
+      }
+    }
+  }
+
   if (per_process::cli_options->print_version) {
     printf("%s\n", NODE_VERSION);
     result.exit_code = 0;

src/node_options.cc

@@ -748,6 +748,10 @@ PerProcessOptionsParser::PerProcessOptionsParser(
             kAllowedInEnvironment);
 #endif
 #endif
+  AddOption("--use-largepages",
+            "Map the Node.js static code to large pages",
+            &PerProcessOptions::use_largepages,
+            kAllowedInEnvironment);
 
   Insert(iop, &PerProcessOptions::get_per_isolate_options);
 }

src/node_options.h

@@ -235,6 +235,7 @@ class PerProcessOptions : public Options {
   bool force_fips_crypto = false;
 #endif
 #endif
+  bool use_largepages = false;
 
 #ifdef NODE_REPORT
   std::vector<std::string> cmdline;

test/parallel/test-startup-large-pages.js

@@ -0,0 +1,19 @@
+'use strict';
+
+// A sanity check: Make sure that Node.js runs correctly when running with the
+// --use-largepages option.
+
+require('../common');
+const assert = require('assert');
+const { spawnSync } = require('child_process');
+
+const child = spawnSync(process.execPath, [ '--use-largepages', '-p', '42' ]);
+const stdout = child.stdout.toString().match(/\S+/g);
+
+assert.strictEqual(child.status, 0);
+assert.strictEqual(child.signal, null);
+assert.strictEqual(stdout.length, 1);
+assert.strictEqual(stdout[0], '42');
+
+// TODO(gabrielschulhof): Make assertions about the stderr, which may or may not
+// contain a message indicating that mapping to large pages has failed.