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What do number conversions cost?

By Meeting C++ | Mar 17, 2023 03:10 AM | Tags: performance meetingcpp intermediate c++20 c++17 basics

Exploring how much number conversions from string cost you and how caching helps

What do number conversions cost?

by Jens Weller

From the article:

And so the devil said: "what if there is an easier design AND implementation?"

In the last two blog posts I've been exploring some of the ways to implement a certain type that has a string_view and holds a conversion to a type in a variant or any. And my last blog post touched on conversions. And that made me wonder, what if I did not have a cache in the type for conversions? The memory foot print would be much smaller, and implementation could be simple to convert in a toType function on demand. This then would essentially be a type that holds a string_view, but offers ways to convert this view to a type. Adding a cache to hold the converted value is in this case not necessary, as this is done on demand.

About conditional breakpoints

By Meeting C++ | Aug 18, 2022 07:11 AM | Tags: performance intermediate debugging debug basics advanced

A post on conditional breakpoints, including two surveys about their usage.

About conditional brealkpoits

by Jens Weller

From the article:

A few weeks ago someone asked me for advice on finding a specific bug in a larger C++ code base...

I don't remember much of the details, but one of the challenges was that at least some of the code based used public members, and in order to find the bug a change in these members is what they wanted to understand. Adding out put statements into a setter function wasn't possible, as the code did not have those. My suggestion was using a conditional breakpoint. And it also made me curious, if and how they're used with in our community.

Data Orientation For The Win! - Eduardo Madrid - CppCon 2021

By Adrien Hamelin | Jul 22, 2022 01:31 PM | Tags: performance

Registration is now open for CppCon 2022, which starts on September 11 and will again be held both in person and online. To whet your appetite for this year’s conference, we’re posting videos of some of the top-rated talks from last year’s conference. Here’s another CppCon talk video we hope you will enjoy – and why not register today for CppCon 2022 to attend in person, online, or both!

Data Orientation For The Win!

by Eduardo Madrid

Summary of the video:

C++ conferences have had presentations showing the important performance benefits of data-oriented design principles; however, the principles seem to require lots of "manual" effort and "code uglification"; these make the principles less practical, and there haven't been clear recommendations about how to deal with runtime-polymorphic types.

In this talk we will recapitulate on data orientation principles and their benefits showing their application through production-strength Generic Programming components made to support them.

Specific examples include:
1. Structures of arrays instead of arrays of complex structures (a.k.a. "scattering")
2. Support for data oriented designs for runtime-polymorphism without inheritance+virtual (the equivalent of using std::variant or std::function, but generalized as allowed by the Zoo type-erasure framework)
----1. Hybrid buffers: the equivalent of the virtual table pointer is scattered out of the objects solving the "Goldilocks problem" of how big the local buffer should be, objects occupy the available space optimally
----2. Easy (de)serialization through very easy relocatability
----3. Voiding the need for pointers in favor of indices into arrays

HPX V1.8.0 released -- STE||AR Group

By Hartmut Kaiser | May 25, 2022 07:59 AM | Tags: performance parallelism heterogeneous computing distributed computing concurrency c++23 c++20 c++17 c++14 c++11

The STE||AR Group has released V1.8.0 of HPX -- A C++ Standard library for Concurrency and Parallelism.

HPX V1.8.0 Released

We have released HPX 1.8.0 -- a major update to our C++ Standard Library for Concurrency and Parallelism. The HPX parallel algorithms now have been fully adapted to C++20, all existing facilities have been adjusted to conform to this version of the Standard as well. We now can proudly announce full conformance to the C++20 concurrency and parallelism facilities. HPX supports all of the algorithms as specified by C++20. On top of that we support parallel versions of all range-based algorithms and have added support for explicit vectorization to more of our algorithms (using std::experimental::simd). Much work has been done towards implementing P2300 (std::execution) and the underlying senders/receivers facilities. Last but not least, we have finished the refactoring of the whole library into a rather large set of non-cyclically depending components. Finally, the new release comes with a brand new documentation interface!

You can download the release from our releases page or check out the 1.8.0 tag using git. A full list of changes can be found in the release notes.

HPX is a general-purpose parallel C++ runtime system for applications of any scale. It implements all of the related facilities as defined by the C++20 Standard. As of this writing, HPX provides the only widely available open-source implementation of the new C++17 and C++20 parallel algorithms, including a full set of parallel range-based algorithms. Additionally, HPX implements functionalities proposed as part of the ongoing C++ standardization process, such as large parts of the features related parallelism and concurrency as specified by the upcoming C++23 Standard, the C++ Concurrency TS, Parallelism TS V2, data-parallel algorithms, executors, and many more. It also extends the existing C++ Standard APIs to the distributed case (e.g., compute clusters) and for heterogeneous systems (e.g., GPUs).

HPX seamlessly enables a new Asynchronous C++ Standard Programming Model that tends to improve the parallel efficiency of our applications and helps reducing complexities usually associated with parallelism and concurrency.

 

C++20: Heterogeneous Lookup in (Un)ordered Containers--Bartlomiej Filipek

By Adrien Hamelin | Nov 28, 2021 11:45 PM | Tags: performance

Did you know?

C++20: Heterogeneous Lookup in (Un)ordered Containers

by Bartlomiej Filipek

From the article:

Would you like to gain 20…35 or even 50% speed improvements when searching in associative containers? In this blog post, we’ll explore a technique called “heterogenous access” that offers such impressive speedups. We’ll explore ordered containers, and the support for unordered collections added recently in C++20...

Three reasons to pass std::string_view by value--Arthur O’Dwyer

By Adrien Hamelin | Nov 12, 2021 01:14 PM | Tags: performance

You should.

Three reasons to pass std::string_view by value

by Arthur O’Dwyer

From the article:

It is idiomatic to pass std::string_view by value. Let’s see why.

First, a little background recap. In C++, everything defaults to pass-by-value; when you say Widget w you actually get a whole new Widget object. But copying big things can be expensive. So we introduce “pass-by-const-reference” as an optimization of “pass-by-value,” and we tell people to pass big and/or expensive things like std::string by const reference instead of by value.

But for small cheap things — int, char*, std::pair<int, int>, std::span<Widget> — we continue to prefer the sensible default behavior of pass-by-value.

Pass-by-value has at least three performance benefits over pass-by-(const)-reference. I’ll illustrate all three of them via string_view...

C++ String Benchmark -- Giovanni Dicanio

By Giovanni Dicanio | Nov 4, 2021 11:55 AM | Tags: performance

This small article compares different string implementations on the Windows platform.

C++ String Benchmark: STL vs. ATL vs. Custom Pool Allocator

by Giovanni Dicanio

From the article:

I was curious to compare the performance of the STL string implementation versus ATL CString, using Visual Studio 2019, so I wrote some simple C++ benchmark code for this purpose. I also added into the mix a custom string pool allocator.