git: 4113ea3403fc - main - vm_object: speed up page collect flush

The branch main has been updated by dougm:

URL: https://cgit.FreeBSD.org/src/commit/?id=4113ea3403fc6abc5e3c51eb027ccef714c89270

commit 4113ea3403fc6abc5e3c51eb027ccef714c89270
Author:     Doug Moore <dougm@FreeBSD.org>
AuthorDate: 2024-07-29 17:59:24 +0000
Commit:     Doug Moore <dougm@FreeBSD.org>
CommitDate: 2024-07-29 18:02:13 +0000

    vm_object: speed up page collect flush
    
    vm_pageout_cluster prepares an array for passing to vm_pageout_flush
    by starting in the middle of a double-sized array and working out from
    the middle. Using the same technique in vm_object_page_collect_flush
    saves one loop that traverses a piece of linked list, and 80 bytes of
    amd64 binary code.
    
    Reviewed by:    kib
    Differential Revision:  https://reviews.freebsd.org/D46173
---
 sys/vm/vm_object.c | 25 ++++++++++---------------
 1 file changed, 10 insertions(+), 15 deletions(-)

diff --git a/sys/vm/vm_object.c b/sys/vm/vm_object.c
index 0af4402938ba..be21081255c2 100644
--- a/sys/vm/vm_object.c
+++ b/sys/vm/vm_object.c
@@ -1115,17 +1115,14 @@ static int
 vm_object_page_collect_flush(vm_object_t object, vm_page_t p, int pagerflags,
     int flags, boolean_t *allclean, boolean_t *eio)
 {
-	vm_page_t ma[vm_pageout_page_count], p_first, tp;
-	int count, i, mreq, runlen;
+	vm_page_t ma[2 * vm_pageout_page_count], tp;
+	int count, mreq, runlen;
 
 	vm_page_lock_assert(p, MA_NOTOWNED);
 	vm_page_assert_xbusied(p);
 	VM_OBJECT_ASSERT_WLOCKED(object);
-
-	count = 1;
-	mreq = 0;
-
-	for (tp = p; count < vm_pageout_page_count; count++) {
+	ma[vm_pageout_page_count] = p;
+	for (count = 1, tp = p; count < vm_pageout_page_count; count++) {
 		tp = vm_page_next(tp);
 		if (tp == NULL || vm_page_tryxbusy(tp) == 0)
 			break;
@@ -1133,24 +1130,22 @@ vm_object_page_collect_flush(vm_object_t object, vm_page_t p, int pagerflags,
 			vm_page_xunbusy(tp);
 			break;
 		}
+		ma[vm_pageout_page_count + count] = tp;
 	}
 
-	for (p_first = p; count < vm_pageout_page_count; count++) {
-		tp = vm_page_prev(p_first);
+	for (mreq = 0, tp = p; count < vm_pageout_page_count; count++, mreq++) {
+		tp = vm_page_prev(tp);
 		if (tp == NULL || vm_page_tryxbusy(tp) == 0)
 			break;
 		if (!vm_object_page_remove_write(tp, flags, allclean)) {
 			vm_page_xunbusy(tp);
 			break;
 		}
-		p_first = tp;
-		mreq++;
+		ma[vm_pageout_page_count - 1 - mreq] = tp;
 	}
 
-	for (tp = p_first, i = 0; i < count; tp = TAILQ_NEXT(tp, listq), i++)
-		ma[i] = tp;
-
-	vm_pageout_flush(ma, count, pagerflags, mreq, &runlen, eio);
+	vm_pageout_flush(&ma[vm_pageout_page_count - mreq], count, pagerflags,
+	    mreq, &runlen, eio);
 	return (runlen);
 }