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vm_phys: check small blocks to finish allocation

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In vm_phys_alloc_queues_contig, in the case that a sequence of
max-order blocks are sought to fulfill an allocation, a sequence is
ruled out if it does not have enough max-order blocks to satisfy the
allocation. However, there may be smaller blocks of free memory that
follow the last max-order block in the sequence, and they may be big
enough to complete the allocation request, so check for that
possibility before giving up on that block sequence.

Reviewed by:	markj
Tested by:	pho
Differential Revision:	https://reviews.freebsd.org/D34724
This commit is contained in:
Doug Moore 2022-03-31 16:19:55 -05:00
parent bafe3b8804
commit 557dc337e6
1 changed files with 21 additions and 3 deletions
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24
sys/vm/vm_phys.c
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@ -1405,9 +1405,9 @@ vm_phys_alloc_queues_contig(
continue;
/*
* Determine if a sufficient number of
* subsequent blocks to satisfy the
* allocation request are free.
* Determine if a series of free oind-blocks
* starting here can satisfy the allocation
* request.
*/
do {
pa += 1 <<
@ -1416,6 +1416,23 @@ vm_phys_alloc_queues_contig(
goto done;
} while (VM_NFREEORDER - 1 == seg->first_page[
atop(pa - seg->start)].order);
/*
* Determine if an additional series of free
* blocks of diminishing size can help to
* satisfy the allocation request.
*/
for (;;) {
m = &seg->first_page[
atop(pa - seg->start)];
if (m->order == VM_NFREEORDER ||
pa + (2 << (PAGE_SHIFT + m->order))
<= pa_end)
break;
pa += 1 << (PAGE_SHIFT + m->order);
if (pa >= pa_end)
goto done;
}
}
}
}
@ -1423,6 +1440,7 @@ vm_phys_alloc_queues_contig(
done:
for (m = m_ret; m < &m_ret[npages]; m = &m[1 << oind]) {
fl = (*queues)[m->pool];
oind = m->order;
vm_freelist_rem(fl, m, oind);
if (m->pool != VM_FREEPOOL_DEFAULT)
vm_phys_set_pool(VM_FREEPOOL_DEFAULT, m, oind);