From 9887ecbe681bf89896edd53915200eb295bf8b53 Mon Sep 17 00:00:00 2001
From: ad <ad@NetBSD.org>
Date: Sun, 15 Mar 2020 21:06:30 +0000
Subject: [PATCH] uvm_physseg: cluster fields used during RB tree lookup for
 PHYS_TO_VM_PAGE().

---
 sys/uvm/uvm_physseg.c | 11 +++++++----
 1 file changed, 7 insertions(+), 4 deletions(-)

diff --git a/sys/uvm/uvm_physseg.c b/sys/uvm/uvm_physseg.c
index e4dc316457ec..5de39ef6a2cb 100644
--- a/sys/uvm/uvm_physseg.c
+++ b/sys/uvm/uvm_physseg.c
@@ -1,4 +1,4 @@
-/* $NetBSD: uvm_physseg.c,v 1.13 2019/12/21 14:41:44 ad Exp $ */
+/* $NetBSD: uvm_physseg.c,v 1.14 2020/03/15 21:06:30 ad Exp $ */
 
 /*
  * Copyright (c) 1997 Charles D. Cranor and Washington University.
@@ -87,12 +87,15 @@
  * uvm_physseg: describes one segment of physical memory
  */
 struct uvm_physseg {
+	/* used during RB tree lookup for PHYS_TO_VM_PAGE(). */
 	struct  rb_node rb_node;	/* tree information */
 	paddr_t	start;			/* PF# of first page in segment */
 	paddr_t	end;			/* (PF# of last page in segment) + 1 */
+	struct	vm_page *pgs;		/* vm_page structures (from start) */
+
+	/* less performance sensitive fields. */
 	paddr_t	avail_start;		/* PF# of first free page in segment */
 	paddr_t	avail_end;		/* (PF# of last free page in segment) +1  */
-	struct	vm_page *pgs;		/* vm_page structures (from start) */
 	struct  extent *ext;		/* extent(9) structure to manage pgs[] */
 	int	free_list;		/* which free list they belong on */
 	u_int	start_hint;		/* start looking for free pages here */
@@ -121,9 +124,9 @@ struct vm_page *uvm_physseg_seg_alloc_from_slab(uvm_physseg_t, size_t);
 struct uvm_physseg_graph {
 	struct rb_tree rb_tree;		/* Tree for entries */
 	int            nentries;	/* Number of entries */
-};
+} __aligned(COHERENCY_UNIT);
 
-static struct uvm_physseg_graph uvm_physseg_graph;
+static struct uvm_physseg_graph uvm_physseg_graph __read_mostly;
 
 /*
  * Note on kmem(9) allocator usage: