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Comment by BeeOnRope | Hacker News Reader

Author here, happy for any feedback or questions.

You can find the previous article at [1], which goes over the basics and the original finding on Skylake. This new article focuses on Ice Lake but probably mostly makes sense after reading the original. HN discussion of the first part is at [2].

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[1] https://travisdowns.github.io/blog/2020/05/13/intel-zero-opt...

[2] https://news.ycombinator.com/item?id=23169605

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Hi author, thanks for your blog. I've really enjoyed reading many of the articles that you have posted! Thanks taking the time to share your thoughts and research.

Thanks!

I'd like to add my thanks to that of @google234123, while I've not read this (yet) I've seen you and dragontamer discoursing on memory bandwidth and it's quality stuff. And your StackOverflow stuff.

What do you recommend to someone who's a beginner in this kind of performance-profiling related work read up on?

The book that got closest for me was CS:APP, but haven't found anything beyond that. It was also very generic. I'm looking for specifically high-perf optimization techniques for x86-64

Any specific books, websites (other than Agner's) or even other blogs?

Here's a good list to get you started:

https://github.com/mfleming/performance-resources/blob/maste...

Thank you!

Here's an (oldish, 2008) paper which is (was?) the basis for CMU's 18-645 How to Write Fast Code at the time: http://users.ece.cmu.edu/~pueschel/teaching/18-645-CMU-sprin... (I didn't take this personally, so I don't know about more recent versions of the course and couldn't find any publicly).

How To Write Fast Numerical Code: A Small Introduction - Srinivas Chellappa, Franz Franchetti and Markus Püschel

http://spiral.ece.cmu.edu:8080/pub-spiral/abstract.jsp?id=10...

Thank you!

Sadly not related to the content itself, but WebKit browsers seem to misrender your indicator circles in the third graph :(

Thanks, are you on Desktop Safari? I will look into it. No doubt my SVG is just wrong.

Desktop and mobile Safari both do it. Firefox shows the circles in a reasonable place.

Thanks! Issue:

https://github.com/travisdowns/travisdowns.github.io/issues/...

Screenshot appreciated if you have a second. Trying to find a way to run WebKit on Linux...

GNOME Web is WebKit-based, although I am not sure if it would have the issue.

Fixed now! Seems like WebKit either doesn't allow styling of svg elements, doesn't obey the transform origin stuff, or some other interaction.

Any other rendering issues let me know.

WebKit and complex SVG transformations do not go together, sadly. Other than that it seemed fine. Like the new tabs in the other post, by the way!

Very interesting stuff. I wonder, did you try -1 (0xFFFFFFFF)?

What does the effect (or lack thereof) look like when doing xmm stores?

Good question: I checked this for Skylake, but not ICL.

Let me whip something up.

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