WHO'S AWESOME

This week and last weekend I was primarily focusing on memory pools, allocators, CPU caches. I now probably know how allocators work, simply separating memory allocation & objects initialization, for example, reserve() function in std::vector, it doesn’t initialize the allocated data segment, thus permitting better performance when we don’t need initialize the data immediately.

CPU cache is another very interesting & important aspect that can (hugely) influence the performance of our programs, as it’s way faster than main memory (RAM). Smaller is faster. A great resource I found on Tuesday evening was a YouTube video – Scott Meyers’s presentation on code::drive conference 2014, a very humorous & high-quality speech!! Really awesome!

Here are a few slides screenshots, the complete presentation pdf version can be downloaded from here.

There are some interesting tops contained within it: cache lines, false sharing, data-oriented design, etc. Very practical and constructive.

From Wednesday and later, I reviewed my qsort vs std::sort problem in terms of cpu cache and cache lines. I found a hug bug (typo) in my qsort function call (embarrassed). Then I further developed that, added a few more tests (for instance, indirect sort), and drew some charts. The details can be found here.

Supplemented on Nov 24, 2020

About cache associativity: see https://www.youtube.com/watch?v=UCK-0fCchmY, a very detailed & intuitive demonstration.

Additional resource: Gallery of Processor Cache Effects by Igor Ostrovsky.

May I ask you a very personal question? Did anyone ever tell you that you have the face of a Botticelli and the body of a Degas?

Is there a crime against comparing a woman to a work of art?

See detailed pick-up lines here.

This week I had a discussion about error estimates for FEM with Miss White on Wednesday evening. While in communication about our ideas, I found a few things that I had deemed almost perfect, but it turned out that it was never meant to be perfect if you don’t have an in-depth discussion with someone of your profession yet. As well as subsequent interchange of ideas, we inspired and completed each other in the process of communication in an unconscious way.

Sooo, finally, I decided to launch a new project that aims for self-improvement via writing summaries, which can be: insightful thoughts, achievements I’ve made, things I really need to put efforts on, horrible things I’ve committed, interests I would like to nurture, awesome people I’ve encountered, challenges I should take, goals I should strive for, essential changes I must make, … Additionally, it serves an extra benefit of saving my ass from terrible writing skills, given that I’m really not into writing, or some sort of detesting feeling. Evil of laziness :)

Okay, now let’s talk about this deprived week, the week I didn’t write any code. But I did attend two classes. The one on Friday, however, got me understood something – Your mind and thinking concerning a certain discipline will rust if you don’t engage in it for a long time. For example, mathematics. It seems like I haven’t been learning mathematics for quite a long time, the agile mind of mathematics I used to have just gone – it took me an unusual amount of time to figure out some calculations that wouldn’t take a few minutes when I was a sophomore. Of course, it shouldn’t be any surprise, since that’s the mechanism our memories work, typically transient in nature. Once you regain the knowledge, it feels superb!