From 2d5980b406fc1efaa63b8f18bcc1b25ab8ec8268 Mon Sep 17 00:00:00 2001
From: Arseny Kapoulkine <arseny.kapoulkine@gmail.com>
Date: Thu, 14 Apr 2016 08:43:06 -0700
Subject: Adjust XML allocation pages to have the exact specified size
Previously the page size was defining the data size, and due to additional
headers (+ recently removed allocation padding) the actual allocation was a bit
bigger.
The problem is that some allocators round 2^N+k allocations to 2^N+M, which can
result in noticeable waste of space. Specifically, on 64-bit OSX allocating the
previous page size (32k+40) resulted in 32k+512 allocation, thereby wasting 472
bytes, or 1.4%.
Now we have the allocation size specified exactly and just recompute the available
data size, which can in small space savings depending on the allocator.
---
src/pugixml.cpp | 16 ++++++++--------
1 file changed, 8 insertions(+), 8 deletions(-)
(limited to 'src')
diff --git a/src/pugixml.cpp b/src/pugixml.cpp
index e8c10a7..fc48701 100644
--- a/src/pugixml.cpp
+++ b/src/pugixml.cpp
@@ -403,14 +403,6 @@ PUGI__NS_END
#endif
PUGI__NS_BEGIN
- static const size_t xml_memory_page_size =
- #ifdef PUGIXML_MEMORY_PAGE_SIZE
- PUGIXML_MEMORY_PAGE_SIZE
- #else
- 32768
- #endif
- ;
-
#ifdef PUGIXML_COMPACT
static const uintptr_t xml_memory_block_alignment = 4;
#else
@@ -476,6 +468,14 @@ PUGI__NS_BEGIN
#endif
};
+ static const size_t xml_memory_page_size =
+ #ifdef PUGIXML_MEMORY_PAGE_SIZE
+ (PUGIXML_MEMORY_PAGE_SIZE)
+ #else
+ 32768
+ #endif
+ - sizeof(xml_memory_page);
+
struct xml_memory_string_header
{
uint16_t page_offset; // offset from page->data
--
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