强制性链接到Andrei Alexandrescu 2015年CppCon关于分配者的演讲:

https://www.youtube.com/watch?v=LIb3L4vKZ7U

好处是，只是设计它们让你想到如何使用它们:-)

在图形模拟中，我看到自定义分配器用于

std::allocator不直接支持的对齐约束。 通过为短期分配(只是这个框架)和长期分配使用单独的池来最小化碎片。

I personally use Loki::Allocator / SmallObject to optimize memory usage for small objects — it show good efficiency and satisfying performance if you have to work with moderate amounts of really small objects (1 to 256 bytes). It can be up to ~30 times more efficient than standard C++ new/delete allocation if we talk about allocating moderate amounts of small objects of many different sizes. Also, there's a VC-specific solution called "QuickHeap", it brings best possible performance (allocate and deallocate operations just read and write the address of the block being allocated/returned to heap, respectively in up to 99.(9)% cases — depends on settings and initialization), but at a cost of a notable overhead — it needs two pointers per extent and one extra for each new memory block. It's a fastest possible solution for working with huge (10 000++) amounts of objects being created and deleted if you don't need a big variety of object sizes (it creates an individual pool for each object size, from 1 to 1023 bytes in current implementation, so initialization costs may belittle the overall performance boost, but one can go ahead and allocate/deallocate some dummy objects before the application enters it's performance-critical phase(s)).

标准的c++ new/delete实现的问题是，它通常只是C malloc/free分配的包装器，它适用于较大的内存块，比如1024+字节。它在性能方面有显著的开销，有时还会占用额外的内存用于映射。因此，在大多数情况下，自定义分配器的实现方式是最大化性能和/或最小化分配小对象(≤1024字节)所需的额外内存量。

强制性链接到Andrei Alexandrescu 2015年CppCon关于分配者的演讲:

https://www.youtube.com/watch?v=LIb3L4vKZ7U

好处是，只是设计它们让你想到如何使用它们:-)

自定义分配器可以发挥作用的一个领域是游戏开发，特别是在游戏机上，因为它们只有少量内存，没有交换空间。在这样的系统上，您要确保对每个子系统都有严格的控制，这样一个不重要的系统就不能从一个重要的系统窃取内存。池分配器等其他功能可以帮助减少内存碎片。你可以在这里找到一篇关于这个主题的详细的长篇论文:

EASTL—Electronic Arts标准模板库

当使用gpu或其他协处理器时，以特殊的方式在主存中分配数据结构有时是有益的。这种特殊的内存分配方式可以在自定义分配器中以一种方便的方式实现。

在使用加速器时，通过加速器运行时进行自定义分配是有益的，原因如下:

through custom allocation the accelerator runtime or driver is notified of the memory block in addition the operating system can make sure that the allocated block of memory is page-locked (some call this pinned memory), that is, the virtual memory subsystem of the operating system may not move or remove the page within or from memory if 1. and 2. hold and a data transfer between a page-locked memory block and an accelerator is requested, the runtime can directly access the data in main memory since it knows where it is and it can be sure the operating system did not move/remove it this saves one memory copy that would occur with memory that was allocated in a non-page-locked way: the data has to be copied in main memory to a page-locked staging area from with the accelerator can initialize the data transfer (through DMA)