git: d411b285bc29 - main - pmap: Micro-optimize pmap_remove_pages() on amd64 and arm64

[Alan Cox]

The branch main has been updated by alc:

URL: https://cgit.FreeBSD.org/src/commit/?id=d411b285bc293a37e062d8fb15b85212ce16abab

commit d411b285bc293a37e062d8fb15b85212ce16abab
Author:     Alan Cox <alc at FreeBSD.org>
AuthorDate: 2021-07-12 23:25:37 +0000
Commit:     Alan Cox <alc at FreeBSD.org>
CommitDate: 2021-07-13 22:33:23 +0000

    pmap: Micro-optimize pmap_remove_pages() on amd64 and arm64
    
    Reduce the live ranges for three variables so that they do not span the
    call to PHYS_TO_VM_PAGE().  This enables the compiler to generate
    slightly smaller machine code.
    
    Reviewed by:    kib, markj
    MFC after:      1 week
    Differential Revision:  https://reviews.freebsd.org/D31161
---
 sys/amd64/amd64/pmap.c | 14 ++++++++++----
 sys/arm64/arm64/pmap.c | 19 ++++++++++---------
 2 files changed, 20 insertions(+), 13 deletions(-)

diff --git a/sys/amd64/amd64/pmap.c b/sys/amd64/amd64/pmap.c
index f8bd17dc6238..31681e255af1 100644
--- a/sys/amd64/amd64/pmap.c
+++ b/sys/amd64/amd64/pmap.c
@@ -8201,6 +8201,16 @@ pmap_remove_pages(pmap_t pmap)
 					continue;
 				}
 
+				/* Mark free */
+				pc->pc_map[field] |= bitmask;
+
+				/*
+				 * Because this pmap is not active on other
+				 * processors, the dirty bit cannot have
+				 * changed state since we last loaded pte.
+				 */
+				pte_clear(pte);
+
 				if (superpage)
 					pa = tpte & PG_PS_FRAME;
 				else
@@ -8217,8 +8227,6 @@ pmap_remove_pages(pmap_t pmap)
 				    ("pmap_remove_pages: bad tpte %#jx",
 				    (uintmax_t)tpte));
 
-				pte_clear(pte);
-
 				/*
 				 * Update the vm_page_t clean/reference bits.
 				 */
@@ -8232,8 +8240,6 @@ pmap_remove_pages(pmap_t pmap)
 
 				CHANGE_PV_LIST_LOCK_TO_VM_PAGE(&lock, m);
 
-				/* Mark free */
-				pc->pc_map[field] |= bitmask;
 				if (superpage) {
 					pmap_resident_count_adj(pmap, -NBPDR / PAGE_SIZE);
 					pvh = pa_to_pvh(tpte & PG_PS_FRAME);
diff --git a/sys/arm64/arm64/pmap.c b/sys/arm64/arm64/pmap.c
index 7758a84d81d5..8ed1b86bd58c 100644
--- a/sys/arm64/arm64/pmap.c
+++ b/sys/arm64/arm64/pmap.c
@@ -4951,6 +4951,16 @@ pmap_remove_pages(pmap_t pmap)
 					continue;
 				}
 
+				/* Mark free */
+				pc->pc_map[field] |= bitmask;
+
+				/*
+				 * Because this pmap is not active on other
+				 * processors, the dirty bit cannot have
+				 * changed state since we last loaded pte.
+				 */
+				pmap_clear(pte);
+
 				pa = tpte & ~ATTR_MASK;
 
 				m = PHYS_TO_VM_PAGE(pa);
@@ -4964,13 +4974,6 @@ pmap_remove_pages(pmap_t pmap)
 				    ("pmap_remove_pages: bad pte %#jx",
 				    (uintmax_t)tpte));
 
-				/*
-				 * Because this pmap is not active on other
-				 * processors, the dirty bit cannot have
-				 * changed state since we last loaded pte.
-				 */
-				pmap_clear(pte);
-
 				/*
 				 * Update the vm_page_t clean/reference bits.
 				 */
@@ -4988,8 +4991,6 @@ pmap_remove_pages(pmap_t pmap)
 
 				CHANGE_PV_LIST_LOCK_TO_VM_PAGE(&lock, m);
 
-				/* Mark free */
-				pc->pc_map[field] |= bitmask;
 				switch (lvl) {
 				case 1:
 					pmap_resident_count_dec(pmap,