The branch main has been updated by dougm:
URL:
https://cgit.FreeBSD.org/src/commit/?id=e77f4e7f597261bc873227a0dfc05d178c367727
commit e77f4e7f597261bc873227a0dfc05d178c367727
Author: Doug Moore <do...@freebsd.org>
AuthorDate: 2023-08-05 02:09:39 +0000
Commit: Doug Moore <do...@freebsd.org>
CommitDate: 2023-08-05 02:09:39 +0000
vm_phys: tune vm_phys_enqueue_contig loop
Rewrite the final loop in vm_phys_enqueue_contig as a new function,
vm_phys_enq_beg, to reduce amd64 code size.
Reviewed by: kib
Differential Revision: https://reviews.freebsd.org/D41289
---
sys/vm/vm_phys.c | 44 ++++++++++++++++++++++++++++++++++++--------
1 file changed, 36 insertions(+), 8 deletions(-)
diff --git a/sys/vm/vm_phys.c b/sys/vm/vm_phys.c
index a3af3964fba4..bc9db6559bfe 100644
--- a/sys/vm/vm_phys.c
+++ b/sys/vm/vm_phys.c
@@ -680,6 +680,41 @@ vm_phys_split_pages(vm_page_t m, int oind, struct
vm_freelist *fl, int order,
}
}
+/*
+ * Add the physical pages [m, m + npages) at the beginning of a power-of-two
+ * aligned and sized set to the specified free list.
+ *
+ * When this function is called by a page allocation function, the caller
+ * should request insertion at the head unless the lower-order queues are
+ * known to be empty. The objective being to reduce the likelihood of long-
+ * term fragmentation by promoting contemporaneous allocation and (hopefully)
+ * deallocation.
+ *
+ * The physical page m's buddy must not be free.
+ */
+static void
+vm_phys_enq_beg(vm_page_t m, u_int npages, struct vm_freelist *fl, int tail)
+{
+ int order;
+
+ KASSERT(npages == 0 ||
+ (VM_PAGE_TO_PHYS(m) &
+ ((PAGE_SIZE << (fls(npages) - 1)) - 1)) == 0,
+ ("%s: page %p and npages %u are misaligned",
+ __func__, m, npages));
+ while (npages > 0) {
+ KASSERT(m->order == VM_NFREEORDER,
+ ("%s: page %p has unexpected order %d",
+ __func__, m, m->order));
+ order = fls(npages) - 1;
+ KASSERT(order < VM_NFREEORDER,
+ ("%s: order %d is out of range", __func__, order));
+ vm_freelist_add(fl, m, order, tail);
+ m += 1 << order;
+ npages -= 1 << order;
+ }
+}
+
/*
* Add the physical pages [m, m + npages) at the end of a power-of-two aligned
* and sized set to the specified free list.
@@ -1190,14 +1225,7 @@ vm_phys_enqueue_contig(vm_page_t m, u_long npages)
m += 1 << order;
}
/* Free blocks of diminishing size. */
- while (m < m_end) {
- KASSERT(seg == &vm_phys_segs[m->segind],
- ("%s: page range [%p,%p) spans multiple segments",
- __func__, m_end - npages, m));
- order = flsl(m_end - m) - 1;
- vm_freelist_add(fl, m, order, 1);
- m += 1 << order;
- }
+ vm_phys_enq_beg(m, m_end - m, fl, 1);
}
/*
