optimization | Routing optimization module module for Itinero | Router library

The execution engine starts off with a pointer to your loop, and lazily expands it as it needs to find out what IO action to execute next. With your definition of forever, here's what a few iterations of the loop like like in terms of "objects stored in memory":

Reason of the issue

It is expected browserslist to return an entry for each version ("safari 15.2", "safari 15.3") instead of a range ("safari 15.2-15.3"). So, this is just a bug in the parsing logic of Safari browser versions which needs to be corrected and will be done soon in fixed versions of Angular 12/Angular 13. Link to details is here.

IMPORTANT UPDATE:

This is fixed in v12.2.16 and v13.2.1, please update if you are experiencing this issue. Users on v11 shouldn't be affected. Link to details is here. If you can not/do not want to update for any reason, then one of the workarounds below can be used.

Workarounds:

Modify .browserslistrc

Add to .browserslistrc such lines:

To measure the branch you are interested in and particularly the scenario when while loop becomes hot, I've used the following benchmark:

Just remove the "extractCss": true from your production environment, it will resolve the problem.

The reason about it is extractCss is deprecated, and it's value is true by default. See more here: Extracting CSS into JS with Angular 11 (deprecated extractCss)

I believe the premise is to have a compile time assert functionality. Suppose that you wrote

The assembly seems to be checking if either num or den is larger than 2**32 by shifting right by 32 bits and then checking whether the resulting number is 0. Depending on the decision, a 64-bit division (div rsi) or 32-bit division (div esi) is performed.

Presumably this code is generated because the compiler writer thinks the additional checks and potential branch outweigh the costs of doing an unnecessary 64-bit division.

The optimization is called "call-pattern specialization" (a.k.a. SpecConstr) this specializes functions according to which arguments they are applied to. The optimization is described in the paper "Call-pattern specialisation for Haskell programs" by Simon Peyton Jones. The current implementation in GHC is different from what is described in that paper in two highly relevant ways:

1. SpecConstr can apply to any call in the same module, not just recursive calls inside a single definition.
2. SpecConstr can apply to functions as arguments, not just constructors. However, it doesn't work for lambdas, unless they have been floated out by full laziness.

Here is the relevant part of the core that is produced without this optimization, using -fno-spec-constr, and with the -dsuppress-all -dsuppress-uniques -dno-typeable-binds flags:

Here's the code in question, from the Python 3.10 branch (in ceval.c, and called from the same file's implementation of the BINARY_ADD opcode). As @jasonharper noted in a comment, it peeks ahead to see whether the result of the BINARY_ADD will next be bound to the same name from which the left-hand addend came. In fast(), it is (operand came from s and result stored into s), but in slow() it isn't (operand came from s but stored into t).

There's no guarantee this optimization will persist, though. For example, I noticed that your fast() is no faster than your slow() on the current development CPython main branch (which is the current work-in-progress toward an eventual 3.11 release).

As noted, there's no guarantee this optimization will persist. "Serious" Python programmers should know better than to rely on dodgy CPython-specific tricks, and, indeed, PEP 8 explicitly warns against relying on this specific one:

Code should be written in a way that does not disadvantage other implementations of Python (PyPy, Jython, IronPython, Cython, Psyco, and such).

For example, do not rely on CPython's efficient implementation of in-place string concatenation for statements in the form a += b or a = a + b ...

Not memory addressing, memory ordering. i.e. for lock-free atomics used for inter-thread synchronization - in x86, every asm load/store is acquire/release respectively. (With real x86 CPUs doing speculative early loads so performance doesn't suffer under normal conditions when a single thread is operating on memory that other threads aren't writing.)

M1 has hardware support for a mode like that, as well as a weakly-ordered mode to run native AArch64 code most efficiently. See

• https://singhkays.com/blog/apple-silicon-m1-black-magic/#performance-must-suck-when-trying-to-emulate-x86-on-arm-right
• https://www.reddit.com/r/hardware/comments/i0mido/apple_silicon_has_a_runtime_toggle_for_tso_to/.

And yes, https://github.com/saagarjha/TSOEnabler is open-source software to toggle that support. But it's a kernel extension, and code signing makes it tricky to get MacOS to allow it, and you have to sign it or disable signature verification or something:

Supposedly, you should be able to use this if you build and sign the kernel extension (disabling SIP if you aren't using a KEXT signing certificate) and drag it into /Library/Extensions. A dialog should come up to prompt you to enable the extension in the Security & Privacy preferences pane, you allow it from there and restart, and it will be installed. (If you're not seeing it, the permissions on the extension might be wrong: try a chown -R root:wheel.) In practice this can go wrong in many ways, and I have had luck by "resetting everything" and trying to install after doing the following:

[...] see the link for the list of steps

So yes, it's plausible that QEMU's x86 emulation could use the same hardware support that Rosetta-2's x86 emulation does. They're both x86 emulators.

And as you say, the main issue is Apple providing public APIs for enabling the HW mode so people don't have to install this kernel module manually; I'm sure most people wouldn't want to do that. I don't know much about the software situation, I was more interested in the CPU-architecture details.