Is memset optimized?

Is memset optimized?

All zeroing operations that the pool allocator performs and many structure/array initializations that InitAll performs end up going through the memset function. Memset is one of the hottest functions on the operating system and is already quite optimized as a result.

What is the difference between memset and memcpy?

memcpy() copies from one place to another. memset() just sets all pieces of memory to the same.

Is memset faster than fill?

memset can be faster since it is written in assembler, whereas std::fill is a template function which simply does a loop internally.

Is memcpy fast?

memcpy is likely to be the fastest way you can copy bytes around in memory. If you need something faster – try figuring out a way of not copying things around, e.g. swap pointers only, not the data itself.

Why is memset so fast?

memset is generally designed to be very very fast general-purpose setting/zeroing code. It handles all cases with different sizes and alignments, which affect the kinds of instructions you can use to do your work.

How fast is memset C++?

Filling large arrays with zeroes quickly in C++

What can I use instead of memcpy?

memmove() is similar to memcpy() as it also copies data from a source to destination.

Whats faster memset or a for loop?

Most certainly, memset will be much faster than that loop. Note how you treat one character at a time, but those functions are so optimized that set several bytes at a time, even using, when available, MMX and SSE instructions.

How long does it take to memcpy?

Using the new memcpy function takes it to 37.5 sec. So the function is better but using structs kills the program.

What can I use instead of memset?

I have used calloc(), instead of combination of malloc and memset as a work around. calloc is the functional equivalent of malloc + memset. It might be faster due to the potential for standard library optimization over hand rolled code, but probably not enough to make a big difference.

How much slower is memcpy on the servers?

The memcpy performance is 3x slower on the servers compared to our laptops. Edit: I am also testing on another server with slightly higher specs and seeing the same results as the above server

Is memcpy latency constrained on e5?

For the E5 you’ll probably find that ~80 ns is a typical latency to RAM, while client parts are closer to 50 ns. So anything that is RAM latency constrained will run slower on server parts, and as it turns out, memcpy on a single core is latency constrained. that’s confusing because memcpy seems like a bandwidth measurement, right?

Is memmove faster than memcpy?

I would expect memcpy to copy memory pages, which should be much faster than looping. In worst case I would expect memcpy to be as fast as memmove. PS: I know that I cannot replace memmove with memcpy in my code. I know that the code sample mixes C and C++. This question is really just for academic purposes.

Does memcpy use the streaming stores?

You confirmed as much with your “naive” memcpy which also doesn’t use them, as well as my configuring asmlib both to use the streaming stores (slow) and not (fast). The streaming stores hurt the single CPU numbers because: