Gabriel
@dssgabriel.bsky.social
PhD candidate, HPC Software Engineering @cea.fr / DAM
MSc HPC & Simulation from @univparissaclay.bsky.social
Architecture, microbenchmarking & SIMD sorcery. Research on distributed computing, data structures & memory layouts at exascale.
RTFM 👹
MSc HPC & Simulation from @univparissaclay.bsky.social
Architecture, microbenchmarking & SIMD sorcery. Research on distributed computing, data structures & memory layouts at exascale.
RTFM 👹
Reposted by Gabriel
Day 7: Dividing by 10 compiles to... no division at all!
How does the compiler pull this off? Magic constants, bit shifts, and a clever arithmetic trick.
xania.org/202512/07-di...
youtu.be/V9Pvv1tkocM
#AoCO2025
How does the compiler pull this off? Magic constants, bit shifts, and a clever arithmetic trick.
xania.org/202512/07-di...
youtu.be/V9Pvv1tkocM
#AoCO2025
Multiplying our way out of division — Matt Godbolt’s blog
How compilers avoid expensive division with multiplication tricks
xania.org
December 7, 2025 at 11:07 AM
Day 7: Dividing by 10 compiles to... no division at all!
How does the compiler pull this off? Magic constants, bit shifts, and a clever arithmetic trick.
xania.org/202512/07-di...
youtu.be/V9Pvv1tkocM
#AoCO2025
How does the compiler pull this off? Magic constants, bit shifts, and a clever arithmetic trick.
xania.org/202512/07-di...
youtu.be/V9Pvv1tkocM
#AoCO2025
Reposted by Gabriel
#Intel released the "Intel #Xeon6 vs #AMD #EPYC Competitive Infographic" pdf:
cdrdv2-public.intel.com/859022/intel...
cdrdv2-public.intel.com/859022/intel...
December 7, 2025 at 7:27 PM
#Intel released the "Intel #Xeon6 vs #AMD #EPYC Competitive Infographic" pdf:
cdrdv2-public.intel.com/859022/intel...
cdrdv2-public.intel.com/859022/intel...
Reposted by Gabriel
Day 6 of Advent of Compiler Optimisations! Divide by 512—just a shift, right? But the compiler adds extra instructions. Why? A subtle difference between what you asked and what you meant!
xania.org/202512/06-di...
youtu.be/7Rtk0qOX9zs
#AoCO2025
xania.org/202512/06-di...
youtu.be/7Rtk0qOX9zs
#AoCO2025
Division — Matt Godbolt’s blog
Division doesn't have to be slow with some clever tricks
xania.org
December 6, 2025 at 12:49 PM
Day 6 of Advent of Compiler Optimisations! Divide by 512—just a shift, right? But the compiler adds extra instructions. Why? A subtle difference between what you asked and what you meant!
xania.org/202512/06-di...
youtu.be/7Rtk0qOX9zs
#AoCO2025
xania.org/202512/06-di...
youtu.be/7Rtk0qOX9zs
#AoCO2025
Reposted by Gabriel
Day 5 of Advent of Compiler Optimisations! x86 has LEA, but ARM has the barrel shifter—instructions can shift operands cheaply. The compiler uses this to multiply without multiplying!
xania.org/202512/05-ba...
youtu.be/TZubUyr2UEY
#AoCO2025
xania.org/202512/05-ba...
youtu.be/TZubUyr2UEY
#AoCO2025
ARM's barrel shifter tricks — Matt Godbolt’s blog
The ARM architecture has a cool feature, and compilers know how to use it
xania.org
December 5, 2025 at 12:05 PM
Day 5 of Advent of Compiler Optimisations! x86 has LEA, but ARM has the barrel shifter—instructions can shift operands cheaply. The compiler uses this to multiply without multiplying!
xania.org/202512/05-ba...
youtu.be/TZubUyr2UEY
#AoCO2025
xania.org/202512/05-ba...
youtu.be/TZubUyr2UEY
#AoCO2025
Reposted by Gabriel
Day 4 of Advent of Compiler Optimisations! Multiply by constants—which ones use actual multiply? The compiler has tricks to avoid it, then saves you from your own clever hacks.
xania.org/202512/04-mu...
youtu.be/1X88od0miHs
#AoCO2025
xania.org/202512/04-mu...
youtu.be/1X88od0miHs
#AoCO2025
xania.org
December 4, 2025 at 12:07 PM
Day 4 of Advent of Compiler Optimisations! Multiply by constants—which ones use actual multiply? The compiler has tricks to avoid it, then saves you from your own clever hacks.
xania.org/202512/04-mu...
youtu.be/1X88od0miHs
#AoCO2025
xania.org/202512/04-mu...
youtu.be/1X88od0miHs
#AoCO2025
Reposted by Gabriel
NVIDIA Releases CUDA 13.1 With New "CUDA Tile" Programming Model - https://www.phoronix.com/news/NVIDIA-CUDA-13.1
NVIDIA Releases CUDA 13.1 With New "CUDA Tile" Programming Model
NVIDIA just released CUDA 13.1 for what they claim is "the largest and most comprehensive update to the CUDA platform since it was invented two decades ago." The most notable addition with the CUDA 13.1 release is CUDA Tile as a new tile-based programming model...
www.phoronix.com
December 4, 2025 at 10:56 PM
NVIDIA Releases CUDA 13.1 With New "CUDA Tile" Programming Model - https://www.phoronix.com/news/NVIDIA-CUDA-13.1
Reposted by Gabriel
#jj-vcs 0.36.0 us out! Including finally moving the documentation to our own domain, docs.jj-vcs.dev
github.com/jj-vcs/jj/re...
github.com/jj-vcs/jj/re...
Release v0.36.0 · jj-vcs/jj
About
jj is a Git-compatible version control system that is both simple and powerful. See
the installation instructions to get started.
Release highlights
The documentation has moved from https:/...
github.com
December 4, 2025 at 11:41 PM
#jj-vcs 0.36.0 us out! Including finally moving the documentation to our own domain, docs.jj-vcs.dev
github.com/jj-vcs/jj/re...
github.com/jj-vcs/jj/re...
Reposted by Gabriel
Day 3 of Advent of Compiler Optimisations! A while loop, recursion, direct addition—all compile to one instruction. The compiler sees the pattern beneath the code.
xania.org/202512/03-mo...
youtu.be/wHg9lYPMvvE
#AoCO2025
xania.org/202512/03-mo...
youtu.be/wHg9lYPMvvE
#AoCO2025
You can't fool the optimiser — Matt Godbolt’s blog
Pattern recognition can see through obfuscated code to find the right instruction
xania.org
December 3, 2025 at 12:00 PM
Day 3 of Advent of Compiler Optimisations! A while loop, recursion, direct addition—all compile to one instruction. The compiler sees the pattern beneath the code.
xania.org/202512/03-mo...
youtu.be/wHg9lYPMvvE
#AoCO2025
xania.org/202512/03-mo...
youtu.be/wHg9lYPMvvE
#AoCO2025
Reposted by Gabriel
Day 2: Adding two integers on x86? Not with `add`! The compiler uses a completely different instruction—one designed for memory addressing. Why? xania.org/202512/02-ad... youtu.be/BOvg0sGJnes #AoCO2025
Addressing the adding situation — Matt Godbolt’s blog
We learn why adding on x86 isn't as obvious as you might think
xania.org
December 2, 2025 at 11:28 AM
Day 2: Adding two integers on x86? Not with `add`! The compiler uses a completely different instruction—one designed for memory addressing. Why? xania.org/202512/02-ad... youtu.be/BOvg0sGJnes #AoCO2025
Reposted by Gabriel
Ever wonder why compilers use `xor eax, eax` to zero registers? It's smaller AND faster—CPUs optimise it out entirely!
Day 1 of Advent of Compiler Optimisations: xania.org/202512/01-xo...
Video: youtu.be/eLjZ48gqbyg
#AoCO2025
Day 1 of Advent of Compiler Optimisations: xania.org/202512/01-xo...
Video: youtu.be/eLjZ48gqbyg
#AoCO2025
Why xor eax, eax? — Matt Godbolt’s blog
Why do compilers love xor-ing registers so much?
xania.org
December 1, 2025 at 12:12 PM
Ever wonder why compilers use `xor eax, eax` to zero registers? It's smaller AND faster—CPUs optimise it out entirely!
Day 1 of Advent of Compiler Optimisations: xania.org/202512/01-xo...
Video: youtu.be/eLjZ48gqbyg
#AoCO2025
Day 1 of Advent of Compiler Optimisations: xania.org/202512/01-xo...
Video: youtu.be/eLjZ48gqbyg
#AoCO2025
Reposted by Gabriel
I wrote up my notes from #SC25. Have a look: blog.glennklockwood.com/2025/12/sc25...
I’ll keep picking away at the editing, but would love to hear more from others about what stood out to them. I wasn’t at the conference itself as much this years as in the past, so I know I missed a lot.
#HPC
I’ll keep picking away at the editing, but would love to hear more from others about what stood out to them. I wasn’t at the conference itself as much this years as in the past, so I know I missed a lot.
#HPC
SC'25 recap
The annual SC conference was held last week, drawing over 16,000 registrants and 560 exhibitors to in St. Louis, Missouri to talk ab...
blog.glennklockwood.com
December 1, 2025 at 7:27 PM
I wrote up my notes from #SC25. Have a look: blog.glennklockwood.com/2025/12/sc25...
I’ll keep picking away at the editing, but would love to hear more from others about what stood out to them. I wasn’t at the conference itself as much this years as in the past, so I know I missed a lot.
#HPC
I’ll keep picking away at the editing, but would love to hear more from others about what stood out to them. I wasn’t at the conference itself as much this years as in the past, so I know I missed a lot.
#HPC
Reposted by Gabriel
Reposted by Gabriel
📣 The procurement contract for #AliceRecoque, the new European #exascale supercomputer 🖥️ ⚡ located in #France, has been signed by @eurohpc-ju.bsky.social and the selected vendor Eviden! It will be one of the backbones for Europe's network of #AIFactories
🔗 www.eurohpc-ju.europa.eu/contract-sig...
🔗 www.eurohpc-ju.europa.eu/contract-sig...
November 18, 2025 at 11:01 AM
📣 The procurement contract for #AliceRecoque, the new European #exascale supercomputer 🖥️ ⚡ located in #France, has been signed by @eurohpc-ju.bsky.social and the selected vendor Eviden! It will be one of the backbones for Europe's network of #AIFactories
🔗 www.eurohpc-ju.europa.eu/contract-sig...
🔗 www.eurohpc-ju.europa.eu/contract-sig...
Reposted by Gabriel
We’re delighted to welcome Modules to the High Performance Software Foundation as an established project 🎊
Read the announcement ➡️ hpsf.io/blog/2025/hi...
Read the announcement ➡️ hpsf.io/blog/2025/hi...
November 10, 2025 at 2:25 PM
We’re delighted to welcome Modules to the High Performance Software Foundation as an established project 🎊
Read the announcement ➡️ hpsf.io/blog/2025/hi...
Read the announcement ➡️ hpsf.io/blog/2025/hi...
Reposted by Gabriel
#AMD #Zen6 znver6 ISA:
- #AVX512_BMM (CPUID.80000021.EAX[23], VBMACOR16x16x16, VBMACXOR16x16x16, VBITREV)
- #AVX512_FP16
- #AVX_NE_CONVERT
- #AVX_IFMA
- #AVX_VNNI_INT8
Source:
sourceware.org/pipermail/bi...
- #AVX512_BMM (CPUID.80000021.EAX[23], VBMACOR16x16x16, VBMACXOR16x16x16, VBITREV)
- #AVX512_FP16
- #AVX_NE_CONVERT
- #AVX_IFMA
- #AVX_VNNI_INT8
Source:
sourceware.org/pipermail/bi...
November 8, 2025 at 1:11 AM
#AMD #Zen6 znver6 ISA:
- #AVX512_BMM (CPUID.80000021.EAX[23], VBMACOR16x16x16, VBMACXOR16x16x16, VBITREV)
- #AVX512_FP16
- #AVX_NE_CONVERT
- #AVX_IFMA
- #AVX_VNNI_INT8
Source:
sourceware.org/pipermail/bi...
- #AVX512_BMM (CPUID.80000021.EAX[23], VBMACOR16x16x16, VBMACXOR16x16x16, VBITREV)
- #AVX512_FP16
- #AVX_NE_CONVERT
- #AVX_IFMA
- #AVX_VNNI_INT8
Source:
sourceware.org/pipermail/bi...
Reposted by Gabriel
NASM 3.00 Assembler Is Ready With Intel APX & AVX10 Support - https://www.phoronix.com/news/NASM-3.00-APX-AVX10
NASM 3.00 Assembler Is Ready With Intel APX & AVX10 Support
Slipping under my radar in October was the release of NASM 3.00 and the follow-up NASM 3.01 release shortly there after. This widely-used open-source assembler is now ready with support for Intel's Advanced Performance Extensions (APX) and AVX10...
www.phoronix.com
November 2, 2025 at 1:53 PM
NASM 3.00 Assembler Is Ready With Intel APX & AVX10 Support - https://www.phoronix.com/news/NASM-3.00-APX-AVX10
Reposted by Gabriel
Reposted by Gabriel
#anniversaire 🎂 | Le CEA fête ses 80 🕯️ .
Le 18/10/1945, le Général de Gaulle signe l’ordonnance fondatrice du CEA.
⚛️L'organisme a pour ambition d’offrir à la 🇫🇷 la maîtrise de l’atome dans différents domaines de la science, de l’industrie & de la défense nationale
👇Extrait
Le 18/10/1945, le Général de Gaulle signe l’ordonnance fondatrice du CEA.
⚛️L'organisme a pour ambition d’offrir à la 🇫🇷 la maîtrise de l’atome dans différents domaines de la science, de l’industrie & de la défense nationale
👇Extrait
October 18, 2025 at 6:58 AM
#anniversaire 🎂 | Le CEA fête ses 80 🕯️ .
Le 18/10/1945, le Général de Gaulle signe l’ordonnance fondatrice du CEA.
⚛️L'organisme a pour ambition d’offrir à la 🇫🇷 la maîtrise de l’atome dans différents domaines de la science, de l’industrie & de la défense nationale
👇Extrait
Le 18/10/1945, le Général de Gaulle signe l’ordonnance fondatrice du CEA.
⚛️L'organisme a pour ambition d’offrir à la 🇫🇷 la maîtrise de l’atome dans différents domaines de la science, de l’industrie & de la défense nationale
👇Extrait
Reposted by Gabriel
Colleges do a terrible job of teaching C++.
It’s not “C with Classes”. Injected into curriculums as a demonstration of early CS concepts, it leaves many with a sour taste.
Students later immediately fall in love with the first language that *doesn’t* feel that way.
It’s not “C with Classes”. Injected into curriculums as a demonstration of early CS concepts, it leaves many with a sour taste.
Students later immediately fall in love with the first language that *doesn’t* feel that way.
October 13, 2025 at 9:21 PM
Colleges do a terrible job of teaching C++.
It’s not “C with Classes”. Injected into curriculums as a demonstration of early CS concepts, it leaves many with a sour taste.
Students later immediately fall in love with the first language that *doesn’t* feel that way.
It’s not “C with Classes”. Injected into curriculums as a demonstration of early CS concepts, it leaves many with a sour taste.
Students later immediately fall in love with the first language that *doesn’t* feel that way.
Reposted by Gabriel
HPSF Board Member & Kokkos Project Maintainer, Damien Lebrun-Grandié, of Oak Ridge National Laboratory (ORNL) will share a maintainer's perspective on Sustainable HPC Software in #HPC Best Practices Webinar - Oct 15 at 1:00pm EDT 🔎 Learn more:
ideas-productivity.org/events/hpcbp...
ideas-productivity.org/events/hpcbp...
October 7, 2025 at 7:54 PM
HPSF Board Member & Kokkos Project Maintainer, Damien Lebrun-Grandié, of Oak Ridge National Laboratory (ORNL) will share a maintainer's perspective on Sustainable HPC Software in #HPC Best Practices Webinar - Oct 15 at 1:00pm EDT 🔎 Learn more:
ideas-productivity.org/events/hpcbp...
ideas-productivity.org/events/hpcbp...
Reposted by Gabriel
Defer: Resource cleanup in C with GCCs magic
oshub.org/projects/ret...
oshub.org/projects/ret...
Defer: Resource cleanup in C with GCCs magic on OSHub
[Defer Macro]
“Warning: This is experimental, relies on GCC-specific extensions (__attribute__((cleanup)) and nested functions), and is not portabl...
oshub.org
October 1, 2025 at 1:14 PM
Defer: Resource cleanup in C with GCCs magic
oshub.org/projects/ret...
oshub.org/projects/ret...
Reposted by Gabriel
About a month ago, I gave a talk at the Rust Amsterdam meetup about Sguaba (the type-safe spatial math Rust crate), and the recording of that is now online for anyone who wants their head to hurt with frames of reference and coordinate transforms 😅
youtu.be/kESBAiTYMoQ
youtu.be/kESBAiTYMoQ
Sguaba: Type-safe spatial math in Rust
YouTube video by Jon Gjengset
youtu.be
September 29, 2025 at 2:26 PM
About a month ago, I gave a talk at the Rust Amsterdam meetup about Sguaba (the type-safe spatial math Rust crate), and the recording of that is now online for anyone who wants their head to hurt with frames of reference and coordinate transforms 😅
youtu.be/kESBAiTYMoQ
youtu.be/kESBAiTYMoQ
Reposted by Gabriel
Hello you fine Internet folks,
Today we are taking a look Intel's Xeon 6 Memory Subsystem and the changes that Intel made in order to fit up to 128 cores in a single CPU.
Hope y'all enjoy!
chipsandcheese.com/p/a-look-int...
old.chipsandcheese.com/2025/09/26/a...
Today we are taking a look Intel's Xeon 6 Memory Subsystem and the changes that Intel made in order to fit up to 128 cores in a single CPU.
Hope y'all enjoy!
chipsandcheese.com/p/a-look-int...
old.chipsandcheese.com/2025/09/26/a...
A Look into Intel Xeon 6’s Memory Subsystem
Intel’s server dominance has been shaken by high core count competition from the likes of AMD and Arm.
chipsandcheese.com
September 26, 2025 at 4:44 PM
Hello you fine Internet folks,
Today we are taking a look Intel's Xeon 6 Memory Subsystem and the changes that Intel made in order to fit up to 128 cores in a single CPU.
Hope y'all enjoy!
chipsandcheese.com/p/a-look-int...
old.chipsandcheese.com/2025/09/26/a...
Today we are taking a look Intel's Xeon 6 Memory Subsystem and the changes that Intel made in order to fit up to 128 cores in a single CPU.
Hope y'all enjoy!
chipsandcheese.com/p/a-look-int...
old.chipsandcheese.com/2025/09/26/a...
Reposted by Gabriel
This is a font joke.
September 20, 2025 at 8:19 PM
This is a font joke.