SDL_HINT_WIN...APHORE_KERNEL(3)

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version 3.4.18 · 9 versions
, in fedora 43, fedora 44

✨ SDL_HINT_WINDOWS_FORCE_SEMAPHORE_KERNEL ✨

okay so bestie, we're in the SDL3 FUNCTIONS section of the manual and today's main character is SDL_HINT_WINDOWS_FORCE_SEMAPHORE_KERNEL 💅 yes the name is a whole mouthful, i know, but stay with me, it's literally just a little variable that decides whether SDL uses Kernel Semaphores on Windows. that's it. that's the vibe. 🦋

🌸 SYNOPSIS 🌸

#include <SDL3/SDL_hints.h>

#define SDL_HINT_WINDOWS_FORCE_SEMAPHORE_KERNEL "SDL_WINDOWS_FORCE_SEMAPHORE_KERNEL"

like, that's the whole thing. no args, no callbacks, just a string macro. iconic honestly. 🎀

💖 DESCRIPTION 💖

so here's the tea. Kernel Semaphores are inter-process, and they require a context switch on every single interaction. every one. it's giving expensive. 💀

but wait — on Windows 8 and newer, the WaitOnAddress API is available. and using that plus atomics to implement semaphores? increases performance. we love to see it. so SDL will fall back to Kernel Objects on older OS versions, or if it gets forced to by this hint. (yes, the hint can bully SDL into the slow path. that's its whole job.)

this variable can be set to the following values:

  • "0" — Use Atomics and WaitOnAddress API when available, otherwise fall back to Kernel Objects. this is the default, the chill option, the "let SDL cook" option. 😌
  • "1" — Force the use of Kernel Objects in all cases. no exceptions, no atomics, no WaitOnAddress, just Kernel Objects, periodt.
⚠️ bestie listen — this hint should be set before SDL is initialized. set it late and it's just gonna do nothing and you'll be sad. 🙈

🌈 AVAILABILITY 🌈

this hint has been available since SDL 3.2.0. so if you're on something older… yeah no. ✨

and that's the whole page, my love 🫶 this was written for Simple Directmedia Layer, documented as SDL 3.4.18, dated right there alongside it — go off, you gorgeous low-level graphics library, you ate and left no crumbs. 💅👑⭐

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