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From: Xin LI <delphij@FreeBSD.org>
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Subject: svn commit: r227802 - head/sys/fs/tmpfs
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Author: delphij
Date: Mon Nov 21 20:26:22 2011
New Revision: 227802
URL: http://svn.freebsd.org/changeset/base/227802

Log:
  Improve the way to calculate available pages in tmpfs:
  
   - Don't deduct wired pages from total usable counts because it does not
     make any sense.  To make things worse, on systems where swap size is
     smaller than physical memory and use a lot of wired pages (e.g. ZFS),
     tmpfs can suddenly have free space of 0 because of this;
   - Count cached pages as available; [1]
   - Don't count inactive pages as available, technically we could but that
     might be too aggressive; [1]
  
  [1] Suggested by kib@
  
  MFC after:	1 week

Modified:
  head/sys/fs/tmpfs/tmpfs.h

Modified: head/sys/fs/tmpfs/tmpfs.h
==============================================================================
--- head/sys/fs/tmpfs/tmpfs.h	Mon Nov 21 20:07:12 2011	(r227801)
+++ head/sys/fs/tmpfs/tmpfs.h	Mon Nov 21 20:26:22 2011	(r227802)
@@ -502,11 +502,8 @@ int	tmpfs_truncate(struct vnode *, off_t
 static __inline size_t
 tmpfs_mem_info(void)
 {
-	size_t size;
 
-	size = swap_pager_avail + cnt.v_free_count + cnt.v_inactive_count;
-	size -= size > cnt.v_wire_count ? cnt.v_wire_count : size;
-	return size;
+	return (swap_pager_avail + cnt.v_free_count + cnt.v_cache_count);
 }
 
 /* Returns the maximum size allowed for a tmpfs file system.  This macro