It's Time to Pay Attention to Intel's Clear Linux OS Project | Hacker News Reader

It's Time to Pay Attention to Intel's Clear Linux OS Project

forbes.com

32 pointsxkgt16 comments

What are the optimizations, and why can't other distro vendors apply them? Maybe this is a way for Intel to rally other distros into adopting the optimizations

https://clearlinux.org/news-blogs/transparent-use-library-pa...

The optimizations they are applying only exist in hardware made in the last ~9 years.

From some browsing through the patches they apply to the packages it appears they are making extensive use of function multi versioning. Instead of compiling for the lowest common denominator for the target arch they are shipping pre-compiled versions for each generation and using run-time detection to figure out which to load.

Nothing stopping any other distro from copying the approach other than detail work and increased package sizes.

Solus did used some clear Linux tuning back in the days when Ikey (founder) was still main Dev. Now the optimizations are still there, but you feel there are getting more rough edges than less, overall. So can't fully recommend Solus OS like I did a year ago :/

> [Clear Linux is] highly tuned for Intel platforms, with all performance optimizations enabled by default. Those optimizations occur across the entire stack: kernel, libraries, middleware layers, frameworks and runtime.

So, why aren't these optimizations available on other distros, since they seem to make such a difference? Is it only a matter of time?

Probably used to distributing a generic kernel and libs to run everywhere for organizational simplicity, and haven't bothered optimizing intel or amd specific ones yet. But, they certainly could. Architecture on most boxes is x86_64 or the 32-bit version. Don't believe they get more specific than this.

Yes, with these tests showing some ~10% improvements, some distros getting regularly spanked in benchmarks probably will.

My guess: Intel is using one of their super optimizing compilers to get these speeds. I'd wager that if you run this on an AMD CPU, it slows down.

Doesn't seem like the kind of thing a super-optimiser is used for, given the few details available.

You could use a super-optimizer to find code sequences that run as slow as possible on AMD CPU's, I think.

Gentoo was like that. Everything was compiled with -march=native. It didn’t result in a noticeable improvement and you had to wait for everything to compile.

It seems with this distro you won’t have to wait. But I can’t imagine the speed ups will be that noticeable.

Well, the article made them look quite noticeable. 10% is a lot.

10% is not very compelling to get people to switch. Gentoo has boasted numbers like that for years. Admittedly I would definitely consider this over Gentoo (no compiling) - but even one issue that’s not easily googled would eliminate the benefits of this distro.

Hmmmm, so what's Intel's play with this distro? The new RHEL replacement?

Otherwise, Forbes article for this kind of "opinion" makes me very conscious about if this was "prompted" or not. No harm intended just want to be conscious about the behind the scenes stuff.

Author is Jason Evangelho (https://twitter.com/killyourfm) who seems pretty neutral.

To enable better performance on Intel processors, to encourage folks to seek them out, and sell more of them, would be my guess.

I'm not surprised if people are confused about this. I don't think there's any magic involved, but examples I've seen about what they do don't make sense for the numerical code they talk about.

For instance, https://clearlinux.org/news-blogs/transparent-use-library-pa... talks about architecture-specific versions of OpenBLAS, but on x86_64 OpenBLAS dispatches on the architecture. Also it has similar DGEMM performance to MKL, at least on for AVX2 and below, unless avx512 has been improved recently; BLIS is competitive also for AVX512. The example does imply something useful that they seem to have done. That's to add SIMD hwcaps for dynamic loading. This is an important omission from vanilla Linux/ld.so, which means you can't build specific libraries and automatically get the appropriate one loaded for the architecture you're on. (Obviously you can arrange to get the appropriate one with LD_LIBRARY_PATH or ld.so.conf, but...) As far as I remember, the only thing that works for on x86_64 is TLS, i.e. there's a /usr/lib64/tls on Fedora-ish systems, but not a similar one for avx2.

Clear Linux has a script which looks at GCC optimization reports and adds target_clones attributes to C(++?) functions which report they're vectorizable. Many of those won't be helpful. The example I've seen, but don't have to hand, was for FFTW but, like OpenBLAS, that dispatches to SIMD-specific kernels. What the script picks up in the example is useless; I think it's just in a test harness, but at least not something that will make your FFTs go faster. That sort of thing can actually be harmful if firing up the SIMD unit lowers the clock rate to no good effect.

There may be problems with that anyway. I haven't had a chance to investigate closely, but adding target_clones to the generic C kernels for BLIS' DGEMM doesn't get the performance that it should, compared with a straight -march=. [It might be worth noting that you can get about 2/3 the performance of the hand-tuned DGEMM kernels with the generic C and appropriate GCC flags.]

This stuff isn't specific to Intel hardware (v. AMD) except insofar as they choose specific targets, and Zen is similar to Haswell for linear algebra kernels.

I wish Nvidia drivers would work on this OS.

Probably the biggest blame is Nvidia for making a compatibility mess with their drivers.

This would be for cuda on servers.

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