From 82d96cccbc40f53c28dd8288b475e535ef017c3a Mon Sep 17 00:00:00 2001 From: Benjamin Kramer Date: Thu, 30 Sep 2010 16:18:28 +0000 Subject: [PATCH] Grow BumpPtrAllocator's slab size dynamically if we allocated many slabs. This reduces the amount of malloc calls and may reduce memory overhead. Some numbers: ASTContext stats, clang -cc1 -disable-free -fsyntax-only Cocoa_h.m without dynamic growth | with dynamic growth Number of memory regions: 3158 | Number of memory regions: 432 Bytes used: 12333185 | Bytes used: 12333185 Bytes allocated: 12935168 | Bytes allocated: 12800000 Bytes wasted: 601983 (includes alignment, etc) | Bytes wasted: 466815 (includes alignment, etc) ASTContext stats, clang -cc1 -disable-free -fsyntax-only on clang's ASTReader.cpp without dynamic growth | with dynamic growth Number of memory regions: 10987 | Number of memory regions: 551 Bytes used: 42910356 | Bytes used: 42910356 Bytes allocated: 45002752 | Bytes allocated: 44711936 Bytes wasted: 2092396 (includes alignment, etc) | Bytes wasted: 1801580 (includes alignment, etc) git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@115151 91177308-0d34-0410-b5e6-96231b3b80d8 --- lib/Support/Allocator.cpp | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/lib/Support/Allocator.cpp b/lib/Support/Allocator.cpp index 90df262336c..02b45d8af98 100644 --- a/lib/Support/Allocator.cpp +++ b/lib/Support/Allocator.cpp @@ -44,6 +44,12 @@ char *BumpPtrAllocator::AlignPtr(char *Ptr, size_t Alignment) { /// StartNewSlab - Allocate a new slab and move the bump pointers over into /// the new slab. Modifies CurPtr and End. void BumpPtrAllocator::StartNewSlab() { + // If we allocated a big number of slabs already it's likely that we're going + // to allocate more. Increase slab size to reduce mallocs and possibly memory + // overhead. The factors are chosen conservatively to avoid overallocation. + if (BytesAllocated >= SlabSize * 128) + SlabSize *= 2; + MemSlab *NewSlab = Allocator.Allocate(SlabSize); NewSlab->NextPtr = CurSlab; CurSlab = NewSlab; -- 2.34.1