svn commit: r251282 - head/sys/kern

[Konstantin Belousov]

Author: kib
Date: Mon Jun  3 04:16:48 2013
New Revision: 251282
URL: http://svnweb.freebsd.org/changeset/base/251282

Log:
  When auto-sizing the buffer cache, limit the amount of physical memory
  used as the estimation of size, to 32GB.  This provides around 100K of
  buffer headers and corresponding KVA for buffer map at the peak.
  Sizing the cache larger is not useful, also resulting in the wasting
  and exhausting of KVA for large machines.
  
  Reported and tested by:	bdrewery
  Sponsored by:	The FreeBSD Foundation

Modified:
  head/sys/kern/vfs_bio.c

Modified: head/sys/kern/vfs_bio.c
==============================================================================
--- head/sys/kern/vfs_bio.c	Mon Jun  3 04:11:42 2013	(r251281)
+++ head/sys/kern/vfs_bio.c	Mon Jun  3 04:16:48 2013	(r251282)
@@ -560,7 +560,8 @@ kern_vfs_bio_buffer_alloc(caddr_t v, lon
 			nbuf += min((physmem_est - 4096) / factor,
 			    65536 / factor);
 		if (physmem_est > 65536)
-			nbuf += (physmem_est - 65536) * 2 / (factor * 5);
+			nbuf += min((physmem_est - 65536) * 2 / (factor * 5),
+			    32 * 1024 * 1024 / (factor * 5));
 
 		if (maxbcache && nbuf > maxbcache / BKVASIZE)
 			nbuf = maxbcache / BKVASIZE;