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0 pointsarghwhat1y ago0 comments

Just make sure not to get caught in the pitfall that is maximum render speed, which can lead to missing out on efficiency during slow and partial rendering.

Missing damage tracking, always painting everything (even when the window is a full 4k monitor), etc. kills performance and input latency when dealing with realistic redraw workloads like text editing, blinking cursors and progress bars. Much too often to terminals worry only about the performance of `cat /dev/urandom`...

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imron1y ago

> kills performance

And battery.

I gave up on alacritty because it was always using the dedicated graphics card of my MacBook and there was no reasonably way to use the integrated graphics card because it was “low performance”.

mitchellh1y ago

- Ghostty does vsync by default and supports variable refresh rates (DisplayLink). If you're on battery and macOS wants to slow Ghostty down, it can and we respect it.

- Ghostty picks your integrated GPU over dedicated/external

- Ghostty sets non-focused rendering threads as QoS background to go onto E-cores

- Ghostty slows down rendering significantly if the window is obscured completely (not visible)

No idea if Alacritty does this, I'm not commenting about that. They might! I'm just talking from the Ghostty side.

imron1y ago

That's a great approach.

Not sure on the current state of Alacritty, but a few years back the suggested solution for users interested in battery performance was to switch to a different terminal emulator: https://github.com/alacritty/alacritty/issues/3473#issuecomm...

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Filligree1y ago

> - Ghostty slows down rendering significantly if the window is obscured completely (not visible)

About this. For whatever reason, I often end up with foreground windows (e.g. Chrome) covering the background window entirely, except for a sliver a few pixels wide.

Would Ghostty handle this case? I don't believe there's any point in full-speed rendering if less than a single line of text is shown, but the window isn't technically obscured completely.

1 more reply

ayushgun1y ago

> - Ghostty sets non-focused rendering threads as QoS background to go onto E-cores

Assuming you're referring to Apple Silicon chips, how does Ghostty explicitly pin a thread to an E-core? IIRC there isn't an explicit way to do it, but I may be misremembering.

2 more replies

tuananh1y ago

can i configure it to run on dedicated? im on desktop, power consumption is not an issue.

1 more reply

epcoa1y ago

> Missing damage tracking, always painting everything (even when the window is a full 4k monitor),

Out of curiosity, what GPU accelerated terminal does this.

cztomsik1y ago

+1, no idea.

But maybe to add a little bit of context, "damage tracking" means for example, that if there is any ongoing animation (like a spinner), then only a small part of the screen will be re-rendered (with proper vertex-time scissors, so only relevant pixels will be computed). I am not sure if it makes sense in the context of a terminal emulator, but it's certainly a big issue for any non-toy GUI toolkits.

GPUs are incredibly fast parallel computers, so you will likely not observe any perf difference (unless you need order-dependent transparency which you don't), but it might improve your battery life significantly.

arghwhatOP1y ago

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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cayley_graph1y ago

Right, input latency is what matters for me. I'm not seeing whether they've measured that in the docs/on Github.

CalebJohn1y ago

He mentions input latency[1] as one of 4 aspects of being fast that were considered during development. I’m not aware of how that was tested, but would trust that it outperforms Iterm2 in that regard.

[1] https://www.youtube.com/watch?v=cPaGkEesw20&t=3015s

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imron1y ago

> kills performance

And battery.

I gave up on alacritty because it was always using the dedicated graphics card of my MacBook and there was no reasonably way to use the integrated graphics card because it was “low performance”.

mitchellh1y ago

- Ghostty does vsync by default and supports variable refresh rates (DisplayLink). If you're on battery and macOS wants to slow Ghostty down, it can and we respect it.

- Ghostty picks your integrated GPU over dedicated/external

- Ghostty sets non-focused rendering threads as QoS background to go onto E-cores

- Ghostty slows down rendering significantly if the window is obscured completely (not visible)

No idea if Alacritty does this, I'm not commenting about that. They might! I'm just talking from the Ghostty side.

imron1y ago

That's a great approach.

2 more replies

Filligree1y ago

> - Ghostty slows down rendering significantly if the window is obscured completely (not visible)

About this. For whatever reason, I often end up with foreground windows (e.g. Chrome) covering the background window entirely, except for a sliver a few pixels wide.

Would Ghostty handle this case? I don't believe there's any point in full-speed rendering if less than a single line of text is shown, but the window isn't technically obscured completely.

1 more reply

ayushgun1y ago

> - Ghostty sets non-focused rendering threads as QoS background to go onto E-cores

Assuming you're referring to Apple Silicon chips, how does Ghostty explicitly pin a thread to an E-core? IIRC there isn't an explicit way to do it, but I may be misremembering.

2 more replies

tuananh1y ago

can i configure it to run on dedicated? im on desktop, power consumption is not an issue.

1 more reply

epcoa1y ago

> Missing damage tracking, always painting everything (even when the window is a full 4k monitor),

Out of curiosity, what GPU accelerated terminal does this.

cztomsik1y ago

+1, no idea.

arghwhatOP1y ago

2 more replies

cayley_graph1y ago

Right, input latency is what matters for me. I'm not seeing whether they've measured that in the docs/on Github.

CalebJohn1y ago

[1] https://www.youtube.com/watch?v=cPaGkEesw20&t=3015s

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