From 8c53a36effa1c4bbdbf94d37afd66e19593844f1 Mon Sep 17 00:00:00 2001
From: sekrit-twc <noreply@example.com>
Date: Sat, 24 Mar 2018 14:43:51 -0700
Subject: [PATCH] Allocate buffers with huge pages.

---
 src/core/vscore.cpp | 75 ++++++++++++++++++++++++++++++++++++++++++++++++++---
 1 file changed, 71 insertions(+), 4 deletions(-)

diff --git a/src/core/vscore.cpp b/src/core/vscore.cpp
index 13573b8..c570b5f 100644
--- a/src/core/vscore.cpp
+++ b/src/core/vscore.cpp
@@ -238,6 +238,62 @@ void VSVariant::initStorage(VSVType t) {

 ///////////////

+static bool do_enable_hugepages()
+{
+	HANDLE token = INVALID_HANDLE_VALUE;
+	TOKEN_PRIVILEGES priv = {};
+
+	if (!(OpenProcessToken(GetCurrentProcess(), TOKEN_ADJUST_PRIVILEGES | TOKEN_QUERY, &token)))
+		return false;
+
+	if (!(LookupPrivilegeValue(nullptr, SE_LOCK_MEMORY_NAME, &priv.Privileges[0].Luid))) {
+		CloseHandle(token);
+		return false;
+	}
+
+	priv.PrivilegeCount = 1;
+	priv.Privileges[0].Attributes = SE_PRIVILEGE_ENABLED;
+
+	if (!(AdjustTokenPrivileges(token, FALSE, &priv, 0, nullptr, 0))) {
+		CloseHandle(token);
+		return false;
+	}
+
+	CloseHandle(token);
+	return true;
+}
+
+static bool enable_hugepages()
+{
+	static const bool enabled = do_enable_hugepages();
+	return enabled;
+}
+
+static uint8_t *alloc_large_page(size_t bytes)
+{
+	if (!enable_hugepages())
+		return nullptr;
+
+	static const size_t pagesize = GetLargePageMinimum();
+
+	if (bytes % pagesize)
+		bytes += pagesize - bytes % pagesize;
+
+	void *buf = VirtualAllocEx(GetCurrentProcess(), nullptr, bytes, MEM_COMMIT | MEM_RESERVE | MEM_LARGE_PAGES, PAGE_READWRITE);
+	if (!buf)
+		vsFatal("memory allocation failed");
+	return (uint8_t *)buf;
+}
+
+static void free_large_page(void *ptr)
+{
+	if (!enable_hugepages()) {
+		vs_aligned_free(ptr);
+		return;
+	}
+	VirtualFreeEx(GetCurrentProcess(), ptr, 0, MEM_RELEASE);
+}
+
 void MemoryUse::add(size_t bytes) {
     used.fetch_add(bytes);
 }
@@ -260,8 +316,14 @@ uint8_t *MemoryUse::allocBuffer(size_t bytes) {
         }
     }

-    uint8_t *buf = vs_aligned_malloc<uint8_t>(VSFrame::alignment + bytes, VSFrame::alignment);
-    memcpy(buf, &bytes, sizeof(bytes));
+	uint8_t *buf = nullptr;
+
+	if (bytes >= 2UL * (1UL << 20))
+		buf = alloc_large_page(bytes);
+	if (!buf)
+		buf = vs_aligned_malloc<uint8_t>(VSFrame::alignment + bytes, VSFrame::alignment);
+
+	memcpy(buf, &bytes, sizeof(bytes));
     return buf + VSFrame::alignment;
 }

@@ -279,8 +341,13 @@ void MemoryUse::freeBuffer(uint8_t *buf) {
         std::advance(iter, randSrc(generator));
         assert(unusedBufferSize >= iter->first);
         unusedBufferSize -= iter->first;
-        vs_aligned_free(iter->second);
-        buffers.erase(iter);
+
+		if (iter->first >= 2UL * (1UL << 20))
+			free_large_page(iter->second);
+		else
+			vs_aligned_free(iter->second);
+
+		buffers.erase(iter);
     }
 }

--
2.13.2.windows.1