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tux3yesterday at 4:24 PM5 repliesview on HN

A bit strange to use time to first token instead of throughput.

Latency to the first token is not like a web page where first paint already has useful things to show. The first token is "The ", and you'll be very happy it's there in 50ms instead of 200ms... but then what you really want to know is how quickly you'll get the rest of the sentence (throughput)


Replies

jbellisyesterday at 4:44 PM

As far as benchmarketing goes they clearly went with prefill because it's much easier for apple to improve prefill numbers (flops-dominated) than decode (bandwidth-dominated, at least for local inference); M5 unified memory bandwidth is only about 10% better than the M4.

GeekyBearyesterday at 4:31 PM

In previous generations, throughout was excellent for an integrated GPU, but the time to first token was lacking.

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hedgehogyesterday at 10:24 PM

Not strange, for the kind of applications models at that size are often used for the prefill is the main factor in responsiveness. Large prompt, small completion.

case540yesterday at 4:43 PM

I assume it’s time to first output token so it’s basically throughput. How fast can it output 8001 tokens

fragmedeyesterday at 4:38 PM

No you don't. Not as a sticky mushy human with emotions watching tokens drip in. There's a lot of feeling and emotion not backed by hard facts and data going around, and most people would rather see something happening even if it takes longer overall. Hence spinner.gif, that doesn't actually remotely do a damned thing, but it gives users reassurance that they're waiting for something good. So human psychology makes time to first token an important metric to look at, although it's not the only one.

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