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vm_phys_early_alloc(): Prefer allocation at boundaries by default
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Authored by olce on Jan 23 2025, 5:16 PM.
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markj
dougm
alc
Summary

This is in preparation for a revamp of vm_page_startup() that will try
to allocate early memory at boundaries in order to reduce the span of
physical addresses to cover in the VM_PHYSSEG_DENSE model.

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rG FreeBSD src repository
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Buildable 62309
Build 59193: arc lint + arc unit

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olce requested review of this revision.Jan 23 2025, 5:16 PM

I think it makes sense to revise this change to be conditional on VM_PHYSSEG_DENSE (and on the condition: vm_domains == 1 or PMAP_HAS_PAGE_ARRAY absent) in order to avoid disabling the anti-fragmentation mechanism on VM_PHYSSEG_SPARSE.

Impacts of parent revisions' changes.

I think it makes sense to revise this change to be conditional on VM_PHYSSEG_DENSE (and on the condition: vm_domains == 1 or PMAP_HAS_PAGE_ARRAY absent) in order to avoid disabling the anti-fragmentation mechanism on VM_PHYSSEG_SPARSE.

In the end not needed, as I changed the policy of allocation at boundaries to have a similar anti-fragmentation mechanism (see D48365).