What is cache friendly code?

Cache friendly code tries to keep accesses close together in memory so that you minimize cache misses. So an example would be imagine you wanted to copy a giant 2 dimensional table. It is organized with reach row in consecutive in memory, and one row follow the next right after.

How do you write a cache efficient code?

An important aspect of cache-friendly code is the principle of locality, the goal of which is to place related data close together in the register-RAM-cache hierarchy to allow efficient caching. In terms of the CPU cache, we have to talk about cache lines. First, lets look at temporal locality.

Which of the above two sorting techniques is cache friendly?

Merging uses the cache more efficiently than Quicksort, but it executes more instructions for a given problem size. Thus Quicksort is a better choice for sorting runs that fit in cache.

Is std :: vector cache friendly?

Because std::vector is cache-friendly. We will look at the design and implementation of awesome cache-friendly containers the standard library lacks, a range of tricks (and hacks) to fit as many objects into the cache as possible, as well as big picture structural program changes for data oriented design.

How are arrays cache friendly?

In particular, arrays are contiguous memory blocks, so large chunks of them will be loaded into the cache upon first access. This makes it comparatively quick to access future elements of the array.

What is good or bad program locality?

Programs with good locality generally run faster as they have lower cache miss rate in comparison with the ones with bad locality.

What is cache efficiency?

There are two terms used to characterize the cache efficiency of a program: the cache hit rate and the cache miss rate. The hit rate is the number of cache hits divided by the total number of memory requests over a given time interval.

What is cache friendliness?

(1) Writing source code with programming structures that align more favorably with memory caches. See cache. (2) Designing a website with Web caching in mind.

Why are arrays cache friendly?

What is meant by cache locality?

Temporal locality means current data or instruction that is being fetched may be needed soon. So we should store that data or instruction in the cache memory so that we can avoid again searching in main memory for the same data.

What are the 3 types of cache misses?

There are three basic types of cache misses known as the 3Cs and some other less popular cache misses.

• Compulsory misses.
• Conflict misses.
• Capacity misses.
• Coherence misses.
• Coverage misses.
• System-related misses.

What is the difference between cache-friendly and cache-unfriendly in C++?

A simple example of cache-friendly versus cache-unfriendly is c++ ‘s std::vector versus std::list. Elements of a std::vector are stored in contiguous memory, and as such accessing them is much more cache-friendly than accessing elements in a std::list, which stores its content all over the place. This is due to spatial locality.

How can I Make my code cache friendly?

The basic approach on how a code can be cache friendly is: Frequently used cases need to be faster: Programs often invest most of the time in a few core functions and these functions in return have most to do with the loops. So, these loops should be designed in a way that they possess a good locality.

Why does critical code lead to more cache misses?

When your critical code contains (unpredictable) branches, it is hard or impossible to prefetch data. This will indirectly lead to more cache misses. This is explained very well here (thanks to @0x90 for the link): Why is processing a sorted array faster than processing an unsorted array?

What is cache in computer architecture?

The idea of caching the useful data centers around a fundamental property of computer programs known as locality. Programs with good locality tend to access the same set of data items over and over again from the upper levels of the memory hierarchy (i.e. cache) and thus run faster.