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src: large pages option: FreeBSD support proposal

Enabling on amd64 and as Linux, are 2MB large.
The ELF section linkage script is compatible only with GNU ld.

PR-URL: #28331
Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Rich Trott <rtrott@gmail.com>
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devnexen authored and Trott committed Jun 20, 2019
1 parent 2a15037 commit a1cb14a4dc69ac2ae9eef0c4620681fada51d9f3
Showing with 110 additions and 9 deletions.
  1. +9 −8 configure.py
  2. +1 −1 node.gyp
  3. +100 −0 src/large_pages/node_large_page.cc
@@ -1039,22 +1039,23 @@ def configure_node(o):
else:
o['variables']['node_use_dtrace'] = 'false'

if options.node_use_large_pages and flavor != 'linux':
if options.node_use_large_pages and not flavor in ('linux', 'freebsd'):
raise Exception(
'Large pages are supported only on Linux Systems.')
if options.node_use_large_pages and flavor == 'linux':
if options.node_use_large_pages and flavor in ('linux', 'freebsd'):
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.')
# 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":
raise Exception(
'Large pages need Linux kernel version >= 2.6.38')
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)

if options.no_ifaddrs:
@@ -811,7 +811,7 @@
}],
],
}],
[ 'node_use_large_pages=="true" and OS=="linux"', {
[ 'node_use_large_pages=="true" and OS in "linux freebsd"', {
'defines': [ 'NODE_ENABLE_LARGE_CODE_PAGES=1' ],
# The current implementation of Large Pages is under Linux.
# Other implementations are possible but not currently supported.
@@ -21,10 +21,16 @@
// SPDX-License-Identifier: MIT

#include "node_large_page.h"
#include "util.h"
#include "uv.h"

#include <fcntl.h> // _O_RDWR
#include <sys/types.h>
#include <sys/mman.h>
#if defined(__FreeBSD__)
#include <sys/sysctl.h>
#include <sys/user.h>
#endif
#include <unistd.h> // readlink

#include <cerrno> // NOLINT(build/include)
@@ -39,6 +45,7 @@
#include <fstream>
#include <iostream>
#include <sstream>
#include <vector>

// The functions in this file map the text segment of node into 2M pages.
// The algorithm is simple
@@ -88,6 +95,7 @@ inline int64_t hugepage_align_down(int64_t addr) {
// This is also handling the case where the first line is not the binary

static struct text_region FindNodeTextRegion() {
#if defined(__linux__)
std::ifstream ifs;
std::string map_line;
std::string permission;
@@ -141,9 +149,68 @@ static struct text_region FindNodeTextRegion() {
}

ifs.close();
#elif defined(__FreeBSD__)
struct text_region nregion;
nregion.found_text_region = false;

std::string exename;
{
char selfexe[PATH_MAX];
size_t count = sizeof(selfexe);
if (uv_exepath(selfexe, &count))
return nregion;

exename = std::string(selfexe, count);
}

size_t numpg;
int mib[] = {CTL_KERN, KERN_PROC, KERN_PROC_VMMAP, getpid()};
const size_t miblen = arraysize(mib);
if (sysctl(mib, miblen, nullptr, &numpg, nullptr, 0) == -1) {
return nregion;
}

// for struct kinfo_vmentry
numpg = numpg * 4 / 3;
auto alg = std::vector<char>(numpg);

if (sysctl(mib, miblen, alg.data(), &numpg, nullptr, 0) == -1) {
return nregion;
}

char* start = alg.data();
char* end = start + numpg;

while (start < end) {
kinfo_vmentry* entry = reinterpret_cast<kinfo_vmentry*>(start);
const size_t cursz = entry->kve_structsize;
if (cursz == 0) {
break;
}

if (entry->kve_path[0] == '\0') {
continue;
}
bool excmapping = ((entry->kve_protection & KVME_PROT_READ) &&
(entry->kve_protection & KVME_PROT_EXEC));

if (!strcmp(exename.c_str(), entry->kve_path) && excmapping) {
size_t size = entry->kve_end - entry->kve_start;
nregion.found_text_region = true;
nregion.from =
reinterpret_cast<char*>(hugepage_align_up(entry->kve_start));
nregion.to =
reinterpret_cast<char*>(hugepage_align_down(entry->kve_end));
nregion.total_hugepages = size / hps;
break;
}
start += cursz;
}
#endif
return nregion;
}

#if defined(__linux__)
static bool IsTransparentHugePagesEnabled() {
std::ifstream ifs;

@@ -171,6 +238,19 @@ static bool IsTransparentHugePagesEnabled() {
ifs.close();
return ret_status;
}
#elif defined(__FreeBSD__)
static bool IsSuperPagesEnabled() {
// It is enabled by default on amd64
unsigned int super_pages = 0;
size_t super_pages_length = sizeof(super_pages);
if (sysctlbyname("vm.pmap.pg_ps_enabled", &super_pages,
&super_pages_length, nullptr, 0) == -1 ||
super_pages < 1) {
return false;
}
return true;
}
#endif

// Moving the text region to large pages. We need to be very careful.
// 1: This function itself should not be moved.
@@ -206,6 +286,7 @@ MoveTextRegionToLargePages(const text_region& r) {

memcpy(nmem, r.from, size);

#if defined(__linux__)
// We already know the original page is r-xp
// (PROT_READ, PROT_EXEC, MAP_PRIVATE)
// We want PROT_WRITE because we are writing into it.
@@ -233,6 +314,17 @@ MoveTextRegionToLargePages(const text_region& r) {

return -1;
}
#elif defined(__FreeBSD__)
tmem = mmap(start, size,
PROT_READ | PROT_WRITE | PROT_EXEC,
MAP_PRIVATE | MAP_ANONYMOUS | MAP_FIXED |
MAP_ALIGNED_SUPER, -1 , 0);
if (tmem == MAP_FAILED) {
PrintSystemError(errno);
munmap(nmem, size);
return -1;
}
#endif

memcpy(start, nmem, size);
ret = mprotect(start, size, PROT_READ | PROT_EXEC);
@@ -266,14 +358,22 @@ int MapStaticCodeToLargePages() {
return -1;
}

#if defined(__linux__)
if (r.from > reinterpret_cast<void*>(&MoveTextRegionToLargePages))
return MoveTextRegionToLargePages(r);

return -1;
#elif defined(__FreeBSD__)
return MoveTextRegionToLargePages(r);
#endif
}

bool IsLargePagesEnabled() {
#if defined(__linux__)
return IsTransparentHugePagesEnabled();
#else
return IsSuperPagesEnabled();
#endif
}

} // namespace node

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