[src/trunk]: src/sys/arch/alpha Make the list of all pmaps LRU-ordered, and u...

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

details:   https://anonhg.NetBSD.org/src/rev/614602fe1aa8
branches:  trunk
changeset: 473184:614602fe1aa8
user:      thorpej <thorpej%NetBSD.org@localhost>
date:      Sun May 23 22:37:02 1999 +0000

description:
Make the list of all pmaps LRU-ordered, and update a comment regarding
locking.

diffstat:

 sys/arch/alpha/alpha/pmap.c   |  40 ++++++++++++++++++++++++++--------------
 sys/arch/alpha/include/pmap.h |   6 +++---
 2 files changed, 29 insertions(+), 17 deletions(-)

diffs (146 lines):

diff -r 3302fef0330e -r 614602fe1aa8 sys/arch/alpha/alpha/pmap.c
--- a/sys/arch/alpha/alpha/pmap.c       Sun May 23 22:08:17 1999 +0000
+++ b/sys/arch/alpha/alpha/pmap.c       Sun May 23 22:37:02 1999 +0000
@@ -1,4 +1,4 @@
-/* $NetBSD: pmap.c,v 1.97 1999/05/23 17:49:07 thorpej Exp $ */
+/* $NetBSD: pmap.c,v 1.98 1999/05/23 22:37:02 thorpej Exp $ */
 
 /*-
  * Copyright (c) 1998, 1999 The NetBSD Foundation, Inc.
@@ -155,7 +155,7 @@
 
 #include <sys/cdefs.h>                 /* RCS ID & Copyright macro defns */
 
-__KERNEL_RCSID(0, "$NetBSD: pmap.c,v 1.97 1999/05/23 17:49:07 thorpej Exp $");
+__KERNEL_RCSID(0, "$NetBSD: pmap.c,v 1.98 1999/05/23 22:37:02 thorpej Exp $");
 
 #include <sys/param.h>
 #include <sys/systm.h>
@@ -274,9 +274,10 @@
 
 /*
  * List of all pmaps, used to update them when e.g. additional kernel
- * page tables are allocated.
+ * page tables are allocated.  This list is kept LRU-ordered by
+ * pmap_activate().
  */
-LIST_HEAD(, pmap) pmap_all_pmaps;
+TAILQ_HEAD(, pmap) pmap_all_pmaps;
 
 /*
  * The pools from which pmap structures and sub-structures are allocated.
@@ -384,7 +385,8 @@
  *       for a specified managed page.
  *
  *     * pmap_all_pmaps_slock - This lock protects the global list of
- *       all pmaps.
+ *       all pmaps.  Note that a pm_slock must never be held while this
+ *       lock is held.
  *
  *     Address space number management (global ASN counters and per-pmap
  *     ASN state) are not locked; they use arrays of values indexed
@@ -872,7 +874,7 @@
        pool_init(&pmap_pv_pool, sizeof(struct pv_entry), 0, 0, 0, "pvpl",
            0, pmap_pv_page_alloc, pmap_pv_page_free, M_VMPMAP);
 
-       LIST_INIT(&pmap_all_pmaps);
+       TAILQ_INIT(&pmap_all_pmaps);
 
        /*
         * Initialize the ASN logic.
@@ -906,7 +908,7 @@
                pmap_kernel()->pm_asngen[i] = pmap_asn_generation[i];
        }
        simple_lock_init(&pmap_kernel()->pm_slock);
-       LIST_INSERT_HEAD(&pmap_all_pmaps, pmap_kernel(), pm_list);
+       TAILQ_INSERT_TAIL(&pmap_all_pmaps, pmap_kernel(), pm_list);
 
 #if defined(MULTIPROCESSOR)
        /*
@@ -1156,7 +1158,7 @@
        simple_lock_init(&pmap->pm_slock);
 
        simple_lock(&pmap_all_pmaps_slock);
-       LIST_INSERT_HEAD(&pmap_all_pmaps, pmap, pm_list);
+       TAILQ_INSERT_TAIL(&pmap_all_pmaps, pmap, pm_list);
        simple_unlock(&pmap_all_pmaps_slock);
 
        return (pmap);
@@ -1172,6 +1174,7 @@
 pmap_destroy(pmap)
        pmap_t pmap;
 {
+       int refs;
 
 #ifdef DEBUG
        if (pmapdebug & PDB_FOLLOW)
@@ -1181,16 +1184,17 @@
                return;
 
        simple_lock(&pmap->pm_slock);
-       if (--pmap->pm_count > 0) {
-               simple_unlock(&pmap->pm_slock);
+       refs = --pmap->pm_count;
+       simple_unlock(&pmap->pm_slock);
+
+       if (refs > 0)
                return;
-       }
 
        /*
         * Remove it from the global list of all pmaps.
         */
        simple_lock(&pmap_all_pmaps_slock);
-       LIST_REMOVE(pmap, pm_list);
+       TAILQ_REMOVE(&pmap_all_pmaps, pmap, pm_list);
        simple_unlock(&pmap_all_pmaps_slock);
 
 #ifdef DIAGNOSTIC
@@ -2166,6 +2170,14 @@
         */
        alpha_atomic_setbits_q(&pmap->pm_cpus, (1UL << cpu_id));
 
+       /*
+        * Move the pmap to the end of the LRU list.
+        */
+       simple_lock(&pmap_all_pmaps_slock);
+       TAILQ_REMOVE(&pmap_all_pmaps, pmap, pm_list);
+       TAILQ_INSERT_TAIL(&pmap_all_pmaps, pmap, pm_list);
+       simple_unlock(&pmap_all_pmaps_slock);
+
        simple_lock(&pmap->pm_slock);
 
        /*
@@ -3262,8 +3274,8 @@
                 * the pmap is activated).
                 */
                simple_lock(&pmap_all_pmaps_slock);
-               for (pmap = LIST_FIRST(&pmap_all_pmaps); pmap != NULL;
-                    pmap = LIST_NEXT(pmap, pm_list)) {
+               for (pmap = TAILQ_FIRST(&pmap_all_pmaps); pmap != NULL;
+                    pmap = TAILQ_NEXT(pmap, pm_list)) {
                        /*
                         * Don't garbage-collect pmaps that reference
                         * kernel_lev1map.  They don't have any user PT
diff -r 3302fef0330e -r 614602fe1aa8 sys/arch/alpha/include/pmap.h
--- a/sys/arch/alpha/include/pmap.h     Sun May 23 22:08:17 1999 +0000
+++ b/sys/arch/alpha/include/pmap.h     Sun May 23 22:37:02 1999 +0000
@@ -1,7 +1,7 @@
-/* $NetBSD: pmap.h,v 1.29 1999/05/23 17:49:08 thorpej Exp $ */
+/* $NetBSD: pmap.h,v 1.30 1999/05/23 22:37:03 thorpej Exp $ */
 
 /*-
- * Copyright (c) 1998 The NetBSD Foundation, Inc.
+ * Copyright (c) 1998, 1999 The NetBSD Foundation, Inc.
  * All rights reserved.
  *
  * This code is derived from software contributed to The NetBSD Foundation
@@ -103,7 +103,7 @@
  * arrays which hold enough for ALPHA_MAXPROCS.
  */
 struct pmap {
-       LIST_ENTRY(pmap)        pm_list;        /* list of all pmaps */
+       TAILQ_ENTRY(pmap)       pm_list;        /* list of all pmaps */
        pt_entry_t              *pm_lev1map;    /* level 1 map */
        int                     pm_count;       /* pmap reference count */
        struct simplelock       pm_slock;       /* lock on pmap */