C ++减少4096字节的内存页面大小

Question

Now on my system (debianx64)the page size is 4096 bytes. Is there any possibilty to decrease it? I would like to store in memory many small pieces but even for 1 byte reserved I can't use another 4095 because of thing added in 1st message here. Is it true or am I wrong? Is it possible to do it? Thx for replies.

Answer 1

No.

4096 is the smallest page size provided by the x86 platform. This is a limitation imposed by the CPU. It offers larger sizes (up to 4MB, depending on the mode), but this is normally selected by the operating system at boot time.

What you can do is make a relatively large allocation as the backing store for an object pool . Then if you need many small objects, they can all be stored within a single page or memory region. This is a common idiom for improving performance in memory allocations.

Moreover, most sane memory allocators work this way anyway, so it's not necessary to implement an object pool unless you find in profiling that you need it.

Answer 2

Page size is an OS-wide item. You can't just create a new page size for your application only since the page-fault logic has to work with all other processes.

I'm not sure what exactly you're attempting to do. I will say that if you're even worried about this issue, then you need to make your software more cache-friendly by storing and accessing memory consecutively, like in an array.

Answer 3

Page size (which BTW can't be lowered below 4K on x86 platforms) is most likely irrelevant to your situation. If you allocate data on the heap, the question of page size will not arise in the manner you assume.