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From: Alan Cox <alc@FreeBSD.org>
Date: Mon, 2 Jul 2012 05:57:44 +0000 (UTC)
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Subject: svn commit: r237952 - stable/9/sys/i386/i386
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X-List-Received-Date: Mon, 02 Jul 2012 05:57:45 -0000
Author: alc
Date: Mon Jul 2 05:57:44 2012
New Revision: 237952
URL: http://svn.freebsd.org/changeset/base/237952
Log:
MFC r235912
There is no need for pmap_protect() to acquire the page queues lock
unless it is going to access the pv lists or PMAP1/PADDR1.
Modified:
stable/9/sys/i386/i386/pmap.c
Directory Properties:
stable/9/sys/ (props changed)
Modified: stable/9/sys/i386/i386/pmap.c
==============================================================================
--- stable/9/sys/i386/i386/pmap.c Mon Jul 2 05:57:01 2012 (r237951)
+++ stable/9/sys/i386/i386/pmap.c Mon Jul 2 05:57:44 2012 (r237952)
@@ -3125,7 +3125,7 @@ pmap_protect(pmap_t pmap, vm_offset_t sv
vm_offset_t pdnxt;
pd_entry_t ptpaddr;
pt_entry_t *pte;
- int anychanged;
+ boolean_t anychanged, pv_lists_locked;
if ((prot & VM_PROT_READ) == VM_PROT_NONE) {
pmap_remove(pmap, sva, eva);
@@ -3141,10 +3141,16 @@ pmap_protect(pmap_t pmap, vm_offset_t sv
return;
#endif
- anychanged = 0;
+ if (pmap_is_current(pmap))
+ pv_lists_locked = FALSE;
+ else {
+ pv_lists_locked = TRUE;
+resume:
+ vm_page_lock_queues();
+ sched_pin();
+ }
+ anychanged = FALSE;
- vm_page_lock_queues();
- sched_pin();
PMAP_LOCK(pmap);
for (; sva < eva; sva = pdnxt) {
pt_entry_t obits, pbits;
@@ -3179,12 +3185,27 @@ pmap_protect(pmap_t pmap, vm_offset_t sv
*/
if (pmap_protect_pde(pmap,
&pmap->pm_pdir[pdirindex], sva, prot))
- anychanged = 1;
- continue;
- } else if (!pmap_demote_pde(pmap,
- &pmap->pm_pdir[pdirindex], sva)) {
- /* The large page mapping was destroyed. */
+ anychanged = TRUE;
continue;
+ } else {
+ if (!pv_lists_locked) {
+ pv_lists_locked = TRUE;
+ if (!mtx_trylock(&vm_page_queue_mtx)) {
+ if (anychanged)
+ pmap_invalidate_all(
+ pmap);
+ PMAP_UNLOCK(pmap);
+ goto resume;
+ }
+ }
+ if (!pmap_demote_pde(pmap,
+ &pmap->pm_pdir[pdirindex], sva)) {
+ /*
+ * The large page mapping was
+ * destroyed.
+ */
+ continue;
+ }
}
}
@@ -3230,14 +3251,16 @@ retry:
if (obits & PG_G)
pmap_invalidate_page(pmap, sva);
else
- anychanged = 1;
+ anychanged = TRUE;
}
}
}
- sched_unpin();
if (anychanged)
pmap_invalidate_all(pmap);
- vm_page_unlock_queues();
+ if (pv_lists_locked) {
+ sched_unpin();
+ vm_page_unlock_queues();
+ }
PMAP_UNLOCK(pmap);
}