Various small changes to PV entry management:

Constify pc_freemask[].

pmap_pv_reclaim()
  Eliminate "freemask" because it was a pessimization.  Add a comment about
  the resident count adjustment.

free_pv_entry() [i386 only]
  Merge an optimization from amd64 (r233954).

get_pv_entry()
  Eliminate the move to tail of the pv_chunk on the global pv_chunks list.
  (The right strategy needs more thought.  Moreover, there were unintended
  differences between the amd64 and i386 implementation.)

pmap_remove_pages()
  Eliminate unnecessary ()'s.

1 files changed, 5 insertions, 10 deletions

diff --git a/sys/amd64/amd64/pmap.c b/sys/amd64/amd64/pmap.c
index a1d2cf5..35cb131 100644
--- a/sys/amd64/amd64/pmap.c
+++ b/sys/amd64/amd64/pmap.c
@@ -2021,7 +2021,7 @@ pv_to_chunk(pv_entry_t pv)
 #define	PC_FREE1	0xfffffffffffffffful
 #define	PC_FREE2	0x000000fffffffffful
 
-static uint64_t pc_freemask[_NPCM] = { PC_FREE0, PC_FREE1, PC_FREE2 };
+static const uint64_t pc_freemask[_NPCM] = { PC_FREE0, PC_FREE1, PC_FREE2 };
 
 SYSCTL_LONG(_vm_pmap, OID_AUTO, pv_entry_count, CTLFLAG_RD, &pv_entry_count, 0,
 	"Current number of pv entries");
@@ -2070,7 +2070,7 @@ pmap_pv_reclaim(pmap_t locked_pmap)
 	pv_entry_t pv;
 	vm_offset_t va;
 	vm_page_t free, m, m_pc;
-	uint64_t inuse, freemask;
+	uint64_t inuse;
 	int bit, field, freed;
 	
 	rw_assert(&pvh_global_lock, RA_WLOCKED);
@@ -2102,7 +2102,6 @@ pmap_pv_reclaim(pmap_t locked_pmap)
 		 */
 		freed = 0;
 		for (field = 0; field < _NPCM; field++) {
-			freemask = 0;
 			for (inuse = ~pc->pc_map[field] & pc_freemask[field];
 			    inuse != 0; inuse &= ~(1UL << bit)) {
 				bit = bsfq(inuse);
@@ -2131,16 +2130,16 @@ pmap_pv_reclaim(pmap_t locked_pmap)
 						    PGA_WRITEABLE);
 					}
 				}
+				pc->pc_map[field] |= 1UL << bit;
 				pmap_unuse_pt(pmap, va, *pde, &free);	
-				freemask |= 1UL << bit;
 				freed++;
 			}
-			pc->pc_map[field] |= freemask;
 		}
 		if (freed == 0) {
 			TAILQ_INSERT_TAIL(&newtail, pc, pc_lru);
 			continue;
 		}
+		/* Every freed mapping is for a 4 KB page. */
 		pmap_resident_count_dec(pmap, freed);
 		PV_STAT(pv_entry_frees += freed);
 		PV_STAT(pv_entry_spare += freed);
@@ -2261,10 +2260,6 @@ retry:
 				TAILQ_INSERT_TAIL(&pmap->pm_pvchunk, pc,
 				    pc_list);
 			}
-			if (pc != TAILQ_LAST(&pv_chunks, pch)) {
-				TAILQ_REMOVE(&pv_chunks, pc, pc_lru);
-				TAILQ_INSERT_TAIL(&pv_chunks, pc, pc_lru);
-			}
 			pv_entry_count++;
 			PV_STAT(pv_entry_spare--);
 			return (pv);
@@ -4137,7 +4132,7 @@ pmap_remove_pages(pmap_t pmap)
 	TAILQ_FOREACH_SAFE(pc, &pmap->pm_pvchunk, pc_list, npc) {
 		allfree = 1;
 		for (field = 0; field < _NPCM; field++) {
-			inuse = (~(pc->pc_map[field])) & pc_freemask[field];
+			inuse = ~pc->pc_map[field] & pc_freemask[field];
 			while (inuse != 0) {
 				bit = bsfq(inuse);
 				bitmask = 1UL << bit;