3 ms·

> 2d rendering used to be hella fast without the gpu. Right? Define Hella fast. If you want 16ms text rendering (~60 Hz) you pretty much need a GPU today. If

> 2d rendering used to be hella fast without the gpu. Right? Define Hella fast. If you want 16ms text rendering (~60 Hz) you pretty much need a GPU today. If you want 8ms (120Hz) text rendering, there is just no CPU that can handle it today with an OS running next to your text editor doing other stuff. The whole point of Xi was being able to edit huge files (Tb size) on 8k displays at over 120 Hz, and being able to resize the screen and scroll, resize text, with great fonts, without any delay or sluggishness. Xi delivered in some of those things, and druid delivers on some of the others. But essentially, there is no system today where you press a key and that key appears on your screen in less than 8ms. Xi achieves ~16ms on the right platforms - not the fastest but much faster than most text editors. The idea behind Xi was to preserve that as the editor got more features, like syntax highlightning, and it did.

taeric 6y ago
Do you have good benchmarks going over this? Still feels ridiculous. I have a multi core machine running at speeds well above my comprehension and you are saying they can't render simple 2d primitives at speed? That just blows my mind. What are they spending the time on? I get that rendering a full display from scratch could be slow. But updating a single key press should not be. Scrolling? Sure. I guess. But even that feels like we over complicated something in the process. I note that I do not disbelieve you. My asserting that it is ridiculous is that it sounds ridiculous.
- fluffything 6y ago
  https://thume.ca/2020/05/20/making-a-latency-tester/ https://thume.ca/2020/05/20/making-a-latency-tester/ > I have a multi core machine running at speeds well above my comprehension and you are saying they can't render simple 2d primitives at speed? That just blows my mind. What are they spending the time on? Moving memory from RAM to the CPU, doing stuff in the CPU, moving the results back to RAM, moving those results from RAM to the GPU, etc. The CPU is fast, but moving memory around is not, so the CPU and the GPU just end up doing nothing most of the time, waiting for memory most of the time. --- Raph's blog (linked at the top), has a bunch of articles about rendering latency. But just google about typing latency, there are a couple of projects and tools that measure the time between a physical keystroke is pressed, and the letter being rendered on the screen (end-to-end). Beyond the memory copies, what usually happens is also: an interrupt is triggered on the CPU, the kernel might take some time to context switch to catch it, context switching requires saving all registers, and restoring them, and registers have exploded in size over time (e.g. with AVX-512 you need to save quite a bit of memory), then the kernel notifies the application, which needs to do something with the key press, like scheduling a render into a frame buffer, etc. So there are just quite a bit of bounces from here to there in the system, most of which deal with memory latencies, and memory latencies is the part of the system that hasn't been getting much faster over the last 30 years.
Myrmornis 6y ago
> there is no system today where you press a key and that key appears on your screen in less than 8ms. Xi achieves ~16ms on the right platforms How does one measure this? Say for the text editor I'm using (Emacs) or for Chrome/Google Docs?
- Myrmornis 6y ago
  Looks like this post is relevant: https://thume.ca/2020/05/20/making-a-latency-tester/ https://thume.ca/2020/05/20/making-a-latency-tester/

taeric 6y ago

Do you have good benchmarks going over this? Still feels ridiculous. I have a multi core machine running at speeds well above my comprehension and you are saying they can't render simple 2d primitives at speed? That just blows my mind. What are they spending the time on? I get that rendering a full display from scratch could be slow. But updating a single key press should not be. Scrolling? Sure. I guess. But even that feels like we over complicated something in the process. I note that I do not disbelieve you. My asserting that it is ridiculous is that it sounds ridiculous.

fluffything 6y ago
https://thume.ca/2020/05/20/making-a-latency-tester/ https://thume.ca/2020/05/20/making-a-latency-tester/ > I have a multi core machine running at speeds well above my comprehension and you are saying they can't render simple 2d primitives at speed? That just blows my mind. What are they spending the time on? Moving memory from RAM to the CPU, doing stuff in the CPU, moving the results back to RAM, moving those results from RAM to the GPU, etc. The CPU is fast, but moving memory around is not, so the CPU and the GPU just end up doing nothing most of the time, waiting for memory most of the time. --- Raph's blog (linked at the top), has a bunch of articles about rendering latency. But just google about typing latency, there are a couple of projects and tools that measure the time between a physical keystroke is pressed, and the letter being rendered on the screen (end-to-end). Beyond the memory copies, what usually happens is also: an interrupt is triggered on the CPU, the kernel might take some time to context switch to catch it, context switching requires saving all registers, and restoring them, and registers have exploded in size over time (e.g. with AVX-512 you need to save quite a bit of memory), then the kernel notifies the application, which needs to do something with the key press, like scheduling a render into a frame buffer, etc. So there are just quite a bit of bounces from here to there in the system, most of which deal with memory latencies, and memory latencies is the part of the system that hasn't been getting much faster over the last 30 years.

Myrmornis 6y ago

> there is no system today where you press a key and that key appears on your screen in less than 8ms. Xi achieves ~16ms on the right platforms How does one measure this? Say for the text editor I'm using (Emacs) or for Chrome/Google Docs?

Myrmornis 6y ago
Looks like this post is relevant: https://thume.ca/2020/05/20/making-a-latency-tester/ https://thume.ca/2020/05/20/making-a-latency-tester/