[WIP] Multi Step Chunked Prefill - Prefill Steps

[varun-sundar-rabindranath]

Initial PR for batching Prefill Steps in multi-step

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[flozi00]

Are you going to make all 3 of chunked prefill, prefix caching and multi step scheduling compatible?

Or doing multi step and chunked prefill in this PR mainly ?

Prefix caching and chunked prefill are working for some days together from main branch

[varun-sundar-rabindranath]

@flozi00 I am not working on prefix caching compatibility. This is PR's focus is multi-step + chunked-prefill.

[flozi00]

Adding: #7753 as context

[varun-sundar-rabindranath]

Bad performance - Just multi-step is better than multi-step + chunked-prefill. Closing this in favor of #8378 . PR 8378 implements a "Single Step Prefill logic" where the prefills in multi-step can turn into decodes after the first step.