vm_reserv: Introduce vm_reserv_populate_range
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Authored by bnovkov on Oct 18 2024, 5:47 PM.

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alc
markj
kib

Summary

This patch adds a routine for populating a range of pages within a reservation.
Instead of repeatedly calling vm_reserv_populate, this routine uses bit_nset to populate the bitmap in one go and updates the reservation's partpopq state only once.

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rG FreeBSD src repository

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bnovkov created this revision.Oct 18 2024, 5:47 PM

Herald added a subscriber: imp. · View Herald TranscriptOct 18 2024, 5:47 PM

bnovkov requested review of this revision.Oct 18 2024, 5:47 PM

bnovkov added a parent revision: D47180: vm_reserv: Refactor vm_reserv_populate.

bnovkov added a child revision: D47048: vm_reserv: Introduce vm_reserv_alloc_npages.

kib added inline comments.Oct 18 2024, 10:13 PM

sys/vm/vm_reserv.c
630	Either use `__FUNCTION__` or `__func__` consistently, please. `__func__` is better because it is standard.
644	Does it make sense to assert that no bits in range are set, before setting them? Otherwise this update might be too optimistic.

alc added inline comments.Oct 18 2024, 10:31 PM

sys/vm/vm_reserv.c
641–642	This needs to be within a loop. Multiple pages may need to have their psind updated. For example, the range being populated may span multiple 64 KB pages within a 2 MB reservation.
644	This check exists within the caller.
732–733	Call it here.
839–840	And, call it here too.

Adress @kib 's and @alc 's comments:

vm_reserv_populate_range should now properly update psinds for SUBLEVEL-sized superpages
Replaced two 'for loop + vm_reserv_populate' constructs with vm_reserv_populate_range

bnovkov marked 4 inline comments as done.Oct 19 2024, 6:38 PM

alc added inline comments.Nov 16 2024, 11:01 PM

sys/vm/vm_reserv.c
630	Please use `__func__` as that is the C standard name.
644–646	I don't think that this loop is correct. Consider the case where start is a multiple of VM_SUBLEVEL_0_NPAGES. The body of the loop is going to set psind on the previous sublevel (64KB) page.

Address @alc 's comments.

bnovkov marked 2 inline comments as done.Mon, Dec 16, 3:12 PM

bnovkov added inline comments.

sys/vm/vm_reserv.c
630	While we're here, do you want me to do the same for other occurrences of `__FUNCTION__` in `vm_reserv.c`?
644–646	You're right, thank you for catching this.

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sys/

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vm_reserv.c

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vm_reserv: Introduce vm_reserv_populate_rangeNeeds ReviewPublicActions