Impact of CPU L3 cache on editing softwares performance?

[John Mil]

Hi guys 😃

Does a big CPU L3 cache improves the performance of apps like premiere pro, and after effects? helps on faster rendering and smoother video previews? What exactly is the L3 cache memory? and also, what other tasks is the L3 cache memory specifically targeted?

and for example what would be the difference from a 12mb L3 cache CPU to a 128mb L3 cache CPU like the ryzen 9 7950x3d

thank you 😄

[shachar carmi]

the short answer is yes.

the longer answer:

cache memory (L1 - L3) came to solve an issue. that issue is that the processor is WAAAAAY faster than ram, and is spending most of it's time waiting for the data to arrive from ram to be processed. cache memory is located on the processor chip, and is orders of magnitude faster than ram, alas, it is waaaay smaller than ram. it can only hold a few MB altogether. L1, L2 and L3, differ in how "close" they are to the processing cores, and therefore differ in access speed. L1 being the fastest, but also the smallest. for comparison, fetching data from L1 takes one CPU cycle, while fetching from ram takes about 100.

how does it help then? the processor tries to predict what the next bit of memory it will require from ram, and then pre-fetch it to the cache before the processor needs it.

if some piece of software was designed with being cache friendly in mind, having large cachce memory will help reduce read-write times from memory, and will therefore make the usage of the CPU more efficiently when reading/writng a lot of bits of memory from ram. it won't help if the processing is done on the graphics card.

so would it help with premier and after effects? it would, but probably not for all parts of the processe done.

i would suggest looking up benchmark tests that often test on premier and AE. that's the only way to know what the benefit is for some specific software, and therefore decide if it's worth buying or not.

[Mylenium]

All programmer hubub aside, the simple answer is no, especially given how AE works. If at all I would imagine you could create a highly optimized effect and control this internally, but as soon as you have to wait for some external AE function or system call that whole concept breaks down. That and of course most of the time you wouldn't notice much of a difference. We're not talking about processing the whole image buffer in the cache or any of that, just a few bits and bytes of repetitive operations having their results stored in the cache for faster reusal and possibly saving a few CPU processing cycles.

Mylenium