[src/trunk]: src/sys/uvm Activate pages in batch instead of acquring uvm_page...

[ad <ad%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/e5b8f8c53db2
branches:  trunk
changeset: 461598:e5b8f8c53db2
user:      ad <ad%NetBSD.org@localhost>
date:      Sun Dec 01 14:24:43 2019 +0000

description:
Activate pages in batch instead of acquring uvm_pageqlock a zillion times.

diffstat:

 sys/uvm/uvm_amap.c |  20 +++++++++++++-------
 1 files changed, 13 insertions(+), 7 deletions(-)

diffs (51 lines):

diff -r 2eb4d1a97385 -r e5b8f8c53db2 sys/uvm/uvm_amap.c
--- a/sys/uvm/uvm_amap.c        Sun Dec 01 14:20:00 2019 +0000
+++ b/sys/uvm/uvm_amap.c        Sun Dec 01 14:24:43 2019 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: uvm_amap.c,v 1.109 2018/08/12 09:29:16 maxv Exp $      */
+/*     $NetBSD: uvm_amap.c,v 1.110 2019/12/01 14:24:43 ad Exp $        */
 
 /*
  * Copyright (c) 1997 Charles D. Cranor and Washington University.
@@ -35,7 +35,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: uvm_amap.c,v 1.109 2018/08/12 09:29:16 maxv Exp $");
+__KERNEL_RCSID(0, "$NetBSD: uvm_amap.c,v 1.110 2019/12/01 14:24:43 ad Exp $");
 
 #include "opt_uvmhist.h"
 
@@ -56,7 +56,7 @@
  * we are ok).
  */
 static struct pool_cache uvm_amap_cache;
-static kmutex_t amap_list_lock;
+static kmutex_t amap_list_lock __cacheline_aligned;
 static LIST_HEAD(, vm_amap) amap_list;
 
 /*
@@ -1070,13 +1070,19 @@
                 * Drop PG_BUSY on new page.  Since its owner was locked all
                 * this time - it cannot be PG_RELEASED or PG_WANTED.
                 */
-
-               mutex_enter(&uvm_pageqlock);
-               uvm_pageactivate(npg);
-               mutex_exit(&uvm_pageqlock);
                npg->flags &= ~(PG_BUSY|PG_FAKE);
                UVM_PAGE_OWN(npg, NULL);
        }
+       /* Activate all pages.  Some may be missing because of retry above. */
+       mutex_enter(&uvm_pageqlock);
+       for (lcv = 0 ; lcv < amap->am_nused ; lcv++) {
+               anon = amap->am_anon[amap->am_slots[lcv]];
+               KASSERT(anon->an_lock == amap->am_lock);
+               if (anon->an_page != NULL) {
+                       uvm_pageactivate(anon->an_page);
+               }
+       }
+       mutex_exit(&uvm_pageqlock);
        amap_unlock(amap);
 }