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.

PR-URL: nodejs#30954
Reviewed-By: Ben Noordhuis <[email protected]>
Reviewed-By: David Carlier <[email protected]>
Reviewed-By: James M Snell <[email protected]>
Reviewed-By: Anna Henningsen <[email protected]>
Reviewed-By: Colin Ihrig <[email protected]>
Reviewed-By: Gireesh Punathil <[email protected]>
Reviewed-By: Denys Otrishko <[email protected]>
Co-authored-by: David Carlier <[email protected]>

Author: Gabriel Schulhof

configure.py

@@ -392,17 +392,6 @@
     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')
-
-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',
@@ -1030,28 +1019,6 @@ 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

@@ -480,6 +480,22 @@ environment variables.
 
 See `SSL_CERT_DIR` and `SSL_CERT_FILE`.
 
+### `--use-largepages=mode`
+<!-- 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.
+
+The following values are valid for `mode`:
+* `off`: No mapping will be attempted. This is the default.
+* `on`: If supported by the OS, mapping will be attempted. Failure to map will
+  be ignored and a message will be printed to standard error.
+* `silent`: If supported by the OS, mapping will be attempted. Failure to map
+  will be ignored and will not be reported.
+
 ### `--v8-options`
 <!-- YAML
 added: v0.1.3
@@ -676,6 +692,7 @@ 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

@@ -259,6 +259,16 @@ See
 and
 .Ev SSL_CERT_FILE .
 .
+.It Fl -use-largepages Ns = Ns Ar mode
+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
+.Ar mode
+must have one of the following values:
+`off` (the default value, meaning do not map), `on` (map and ignore failure,
+reporting it to stderr), or `silent` (map and silently ignore failure).
+.
 .It Fl -v8-options
 Print V8 command-line options.
 .

node.gyp

@@ -606,10 +606,9 @@
             'src/tls_wrap.h'
           ],
         }],
-        [ 'node_use_large_pages=="true" and OS in "linux freebsd mac"', {
+        [ 'OS in "linux freebsd mac" and '
+          'target_arch=="x64"', {
           'defines': [ 'NODE_ENABLE_LARGE_CODE_PAGES=1' ],
-          # The current implementation of Large Pages is under Linux.
-          # Other implementations are possible but not currently supported.
           'sources': [
             'src/large_pages/node_large_page.cc',
             'src/large_pages/node_large_page.h'

node.gypi

@@ -306,17 +306,15 @@
     }],
     [ 'OS=="linux" and '
       'target_arch=="x64" and '
-      'node_use_large_pages=="true" and '
-      'node_use_large_pages_script_lld=="false"', {
+      'llvm_version==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', {
       'ldflags': [
         '-Wl,-T',
         '<!(realpath src/large_pages/ld.implicit.script.lld)',

src/large_pages/node_large_page.cc

@@ -20,6 +20,7 @@
 //
 // SPDX-License-Identifier: MIT
 
+#include "node_internals.h"
 #include "node_large_page.h"
 #include "util.h"
 #include "uv.h"
@@ -69,7 +70,7 @@
 // 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;
@@ -315,7 +316,7 @@ 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__)
@@ -340,9 +341,6 @@ MoveTextRegionToLargePages(const text_region& r) {
     PrintSystemError(errno);
     return -1;
   }
-  OnScopeLeave munmap_on_return([nmem, size]() {
-    if (-1 == munmap(nmem, size)) PrintSystemError(errno);
-  });
 
   memcpy(nmem, r.from, size);
 
@@ -359,13 +357,14 @@ 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);
     if (ret == -1) {
       PrintSystemError(errno);
     }
+    if (-1 == munmap(nmem, size)) PrintSystemError(errno);
     return -1;
   }
   memcpy(start, nmem, size);
@@ -376,6 +375,7 @@ MoveTextRegionToLargePages(const text_region& r) {
               MAP_ALIGNED_SUPER, -1 , 0);
   if (tmem == MAP_FAILED) {
     PrintSystemError(errno);
+    if (-1 == munmap(nmem, size)) PrintSystemError(errno);
     return -1;
   }
 #elif defined(__APPLE__)
@@ -390,6 +390,7 @@ MoveTextRegionToLargePages(const text_region& r) {
               VM_FLAGS_SUPERPAGE_SIZE_2MB, 0);
   if (tmem == MAP_FAILED) {
     PrintSystemError(errno);
+    if (-1 == munmap(nmem, size)) PrintSystemError(errno);
     return -1;
   }
   memcpy(tmem, nmem, size);
@@ -400,6 +401,7 @@ MoveTextRegionToLargePages(const text_region& r) {
     if (ret == -1) {
       PrintSystemError(errno);
     }
+    if (-1 == munmap(nmem, size)) PrintSystemError(errno);
     return -1;
   }
   memcpy(start, tmem, size);
@@ -412,8 +414,10 @@ MoveTextRegionToLargePages(const text_region& r) {
     if (ret == -1) {
       PrintSystemError(errno);
     }
+    if (-1 == munmap(nmem, size)) PrintSystemError(errno);
     return -1;
   }
+  if (-1 == munmap(nmem, size)) PrintSystemError(errno);
   return ret;
 }
 
@@ -425,12 +429,12 @@ int MapStaticCodeToLargePages() {
     return -1;
   }
 
-#if defined(__linux__)
+#if defined(__linux__) || defined(__FreeBSD__)
   if (r.from > reinterpret_cast<void*>(&MoveTextRegionToLargePages))
     return MoveTextRegionToLargePages(r);
 
   return -1;
-#elif defined(__FreeBSD__) || defined(__APPLE__)
+#elif defined(__APPLE__)
   return MoveTextRegionToLargePages(r);
 #endif
 }

src/node.cc

@@ -74,9 +74,7 @@
 #include "../deps/v8/src/third_party/vtune/v8-vtune.h"
 #endif
 
-#ifdef NODE_ENABLE_LARGE_CODE_PAGES
 #include "large_pages/node_large_page.h"
-#endif
 
 #include <errno.h>
 #include <fcntl.h>  // _O_RDWR
@@ -3021,14 +3019,6 @@ int Start(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);
 
@@ -3037,6 +3027,26 @@ int Start(int argc, char** argv) {
   // This needs to run *before* V8::Initialize().
   Init(&args, &exec_args);
 
+#if defined(NODE_ENABLE_LARGE_CODE_PAGES) && NODE_ENABLE_LARGE_CODE_PAGES
+  if (per_process_opts->use_largepages == "on" ||
+      per_process_opts->use_largepages == "silent") {
+    if (node::IsLargePagesEnabled()) {
+      if (node::MapStaticCodeToLargePages() != 0 &&
+          per_process_opts->use_largepages != "silent") {
+        fprintf(stderr,
+                "Mapping code to large pages failed. Reverting to default page "
+                "size.\n");
+      }
+    } else if (per_process_opts->use_largepages != "silent") {
+      fprintf(stderr, "Large pages are not enabled.\n");
+    }
+  }
+#else
+  if (per_process_opts->use_largepages == "on") {
+    fprintf(stderr, "Mapping to large pages is not supported.\n");
+  }
+#endif  // NODE_ENABLE_LARGE_CODE_PAGES
+
 #if HAVE_OPENSSL
   {
     std::string extra_ca_certs;

src/node_options.cc

@@ -24,6 +24,11 @@ void PerProcessOptions::CheckOptions(std::vector<std::string>* errors) {
                       "used, not both");
   }
 #endif
+  if (use_largepages != "off" &&
+      use_largepages != "on" &&
+      use_largepages != "silent") {
+    errors->push_back("invalid value for --use-largepages");
+  }
   per_isolate->CheckOptions(errors);
 }
 
@@ -355,6 +360,10 @@ PerProcessOptionsParser::PerProcessOptionsParser() {
             kAllowedInEnvironment);
 #endif
 #endif
+  AddOption("--use-largepages",
+            "Map the Node.js static code to large pages",
+            &PerProcessOptions::use_largepages,
+            kAllowedInEnvironment);
 
   Insert(&PerIsolateOptionsParser::instance,
          &PerProcessOptions::get_per_isolate_options);

src/node_options.h

@@ -153,6 +153,7 @@ class PerProcessOptions : public Options {
   bool force_fips_crypto = false;
 #endif
 #endif
+  std::string use_largepages = "off";
 
   inline PerIsolateOptions* get_per_isolate_options();
   void CheckOptions(std::vector<std::string>* errors);

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

@@ -0,0 +1,29 @@
+'use strict';
+
+// Make sure that Node.js runs correctly with the --use-largepages option.
+
+require('../common');
+const assert = require('assert');
+const { spawnSync } = require('child_process');
+
+{
+  const child = spawnSync(process.execPath,
+                          [ '--use-largepages=on', '-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');
+}
+
+{
+  const child = spawnSync(process.execPath,
+                          [ '--use-largepages=xyzzy', '-p', '42' ]);
+  assert.strictEqual(child.status, 9);
+  assert.strictEqual(child.signal, null);
+  assert.strictEqual(child.stderr.toString().match(/\S+/g).slice(1).join(' '),
+                     'invalid value for --use-largepages');
+}
+
+// TODO(gabrielschulhof): Make assertions about the stderr, which may or may not
+// contain a message indicating that mapping to large pages has failed.