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Comment by saagarjha | Hacker News Reader

iTerm actually disables the Metal rederer while on battery by default.

I think that was the point of their question. While it's disabled by default, if it goes from 12h life to 6h, people will leave disabled. If it goes from 12h to 11.5h, people maybe would consider flipping that toggle.

Kind of counter intuitive. Wouldn’t the GPU be more efficient at rendering graphics than the CPU? For laptop models with dedicated GPU just use the integrated one on battery but ALWAYS prefer Metal GPU rendering to software.

No, it's not. Each visible pane gets its own thread, and three frames are pipelined. That means you could easily keep two cores plus your GPU going full steam (provided you have an underpowered GPU, which you almost certainly do, because you have a mac). In the legacy renderer, everything happened on the main thread so the most power it could draw was one core at 100%.

> In the legacy renderer, everything happened on the main thread so the most power it could draw was one core at 100%.

We’re not talking about wattage, but energy consumption. I.e. a single core working at its max for 5 seconds uses more power than three cores working for one second. It’s a question of efficiency, not how many cores are working at once.

I’m guessing here but given the target of macOS this is done to prevent the GPU from being used. Many apps on macOS can do their drawing on the CPU or via the onboard Intel graphics. Metal presumably would force the GPU on, which would impact battery life.

Except that is not how it works. Metal absolutely works with the integrated GPU.

He wasn't saying metal can render via the cpu, he was saying that macos apps in general can choose whether to use cpu or gpu rendering.

Has the bug been fixed where it doesn't disable? I had to track down why my Nvidia GPU was being used all the time and killing my battery. Turns out it's iTerm2 and it isn't disabling the renderer correctly.

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