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0 pointsarghwhat1y ago0 comments

No, damage tracking is important as it about reporting that you only updated that spinner, which means that your display server also knows to only redraw and repaint that area, and in turn that your GPU knows during scanout that only that area changed.

Without, even if you only redrew your spinner, your display server ends up having to redraw what might be a full screen 4k window, as well as every intersecting window above and below until an opaque surfaces are hit to stop blending.

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epcoa1y ago

Well it sounds like ghostty is like all the other major GPU terminal emulators (unless you know of a counterexample) and does full redraw, though it appears to have some optimizations about how often that occurs.

The power issue might be true in some cases, but even as foot’s own benchmarks against alacritty demonstrate, it’s hyperbolic to say it “kills performance”.

mitchellh1y ago

We do a full redraw but do damage tracking ("dirty tracking" for us) on the cell state so we only rebuild the GPU state that changed. The CPU time to rebuild a frame is way more expensive than the mostly non-existent GPU time to render a frame since our render pipeline is so cheap.

As I said in another thread, this ain't a AAA game. Shading a text grid is basically free on the GPU lol.

arghwhatOP1y ago

It's actually not at all free, even if you're barely using the shading capacity. The issue is that you keep the power-hungry shader units on, whereas when truly idle their power is cut. Battery life is all about letting hardware turn off entirely.

Also, if you do damage tracking, make sure to report it to the display server so they can avoid doing more expensive work blending several sources together, and in case of certain GPUs and certain scanout modes, also more efficient scanout. Depending on your choice of APIs, that would be something like eglSwapBuffersWithDamage, wl_surface_damage_buffer, and so forth.

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epcoa1y ago

Perhaps that came across wrong, no shade intended, what was meant was that ghostty seems to be like all the other mature GPU based emulators. Which means there's no damage reporting to a display server or anything like that. I don't think it's quite the deal breaker the GGP implies.

cztomsik1y ago

That's what I meant to say. There are 2 parts, and both need to work correctly, otherwise you're wasting power.

j / k navigate · click thread line to collapse

0 pointsarghwhat1y ago0 comments

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epcoa1y ago

The power issue might be true in some cases, but even as foot’s own benchmarks against alacritty demonstrate, it’s hyperbolic to say it “kills performance”.

mitchellh1y ago

As I said in another thread, this ain't a AAA game. Shading a text grid is basically free on the GPU lol.

arghwhatOP1y ago

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epcoa1y ago

cztomsik1y ago

That's what I meant to say. There are 2 parts, and both need to work correctly, otherwise you're wasting power.

j / k navigate · click thread line to collapse