Skip site navigation (1)Skip section navigation (2) 
Date:      Mon, 23 Feb 2009 06:00:24 +0000 (UTC)
From:      Alan Cox <alc@FreeBSD.org>
To:        src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org
Subject:   svn commit: r188932 - in head/sys: amd64/amd64 i386/i386
Message-ID:  <200902230600.n1N60ORX016182@svn.freebsd.org>
next in thread | raw e-mail | index | archive | help 
Author: alc
Date: Mon Feb 23 06:00:24 2009
New Revision: 188932
URL: http://svn.freebsd.org/changeset/base/188932

Log:
  Optimize free_pv_entry(); specifically, avoid repeated TAILQ_REMOVE()s.
  
  MFC after:	1 week

Modified:
  head/sys/amd64/amd64/pmap.c
  head/sys/i386/i386/pmap.c

Modified: head/sys/amd64/amd64/pmap.c
==============================================================================
--- head/sys/amd64/amd64/pmap.c	Sun Feb 22 20:11:10 2009	(r188931)
+++ head/sys/amd64/amd64/pmap.c	Mon Feb 23 06:00:24 2009	(r188932)
@@ -1932,15 +1932,15 @@ free_pv_entry(pmap_t pmap, pv_entry_t pv
 	pc->pc_map[field] |= 1ul << bit;
 	/* move to head of list */
 	TAILQ_REMOVE(&pmap->pm_pvchunk, pc, pc_list);
-	TAILQ_INSERT_HEAD(&pmap->pm_pvchunk, pc, pc_list);
 	if (pc->pc_map[0] != PC_FREE0 || pc->pc_map[1] != PC_FREE1 ||
-	    pc->pc_map[2] != PC_FREE2)
+	    pc->pc_map[2] != PC_FREE2) {
+		TAILQ_INSERT_HEAD(&pmap->pm_pvchunk, pc, pc_list);
 		return;
+	}
 	PV_STAT(pv_entry_spare -= _NPCPV);
 	PV_STAT(pc_chunk_count--);
 	PV_STAT(pc_chunk_frees++);
 	/* entire chunk is free, return it */
-	TAILQ_REMOVE(&pmap->pm_pvchunk, pc, pc_list);
 	m = PHYS_TO_VM_PAGE(DMAP_TO_PHYS((vm_offset_t)pc));
 	dump_drop_page(m->phys_addr);
 	vm_page_unwire(m, 0);

Modified: head/sys/i386/i386/pmap.c
==============================================================================
--- head/sys/i386/i386/pmap.c	Sun Feb 22 20:11:10 2009	(r188931)
+++ head/sys/i386/i386/pmap.c	Mon Feb 23 06:00:24 2009	(r188932)
@@ -1975,15 +1975,15 @@ free_pv_entry(pmap_t pmap, pv_entry_t pv
 	pc->pc_map[field] |= 1ul << bit;
 	/* move to head of list */
 	TAILQ_REMOVE(&pmap->pm_pvchunk, pc, pc_list);
-	TAILQ_INSERT_HEAD(&pmap->pm_pvchunk, pc, pc_list);
 	for (idx = 0; idx < _NPCM; idx++)
-		if (pc->pc_map[idx] != pc_freemask[idx])
+		if (pc->pc_map[idx] != pc_freemask[idx]) {
+			TAILQ_INSERT_HEAD(&pmap->pm_pvchunk, pc, pc_list);
 			return;
+		}
 	PV_STAT(pv_entry_spare -= _NPCPV);
 	PV_STAT(pc_chunk_count--);
 	PV_STAT(pc_chunk_frees++);
 	/* entire chunk is free, return it */
-	TAILQ_REMOVE(&pmap->pm_pvchunk, pc, pc_list);
 	m = PHYS_TO_VM_PAGE(pmap_kextract((vm_offset_t)pc));
 	pmap_qremove((vm_offset_t)pc, 1);
 	vm_page_unwire(m, 0);

Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?200902230600.n1N60ORX016182>