svn commit: r272153 - head/lib/libthr

[Sergey Kandaurov]

Author: pluknet
Date: Fri Sep 26 04:33:27 2014
New Revision: 272153
URL: http://svnweb.freebsd.org/changeset/base/272153

Log:
  Fix description of mutex acquisition.
  
  Reviewed by:	kib
  X-MFC with:	r272070
  Sponsored by:	Nginx, Inc.

Modified:
  head/lib/libthr/libthr.3

Modified: head/lib/libthr/libthr.3
==============================================================================
--- head/lib/libthr/libthr.3	Fri Sep 26 03:03:58 2014	(r272152)
+++ head/lib/libthr/libthr.3	Fri Sep 26 04:33:27 2014	(r272153)
@@ -29,7 +29,7 @@
 .\"
 .\" $FreeBSD$
 .\"
-.Dd September 20, 2014
+.Dd September 26, 2014
 .Dt LIBTHR 3
 .Os
 .Sh NAME
@@ -85,8 +85,14 @@ owning the lock.
 .Nm
 performs a contested mutex acquisition in three stages, each of which
 is more resource-consuming than the previous.
+The first two stages are only applied for a mutex of
+.Dv PTHREAD_MUTEX_ADAPTIVE_NP
+type and
+.Dv PTHREAD_PRIO_NONE
+protocol (see
+.Xr pthread_mutexattr 3 ) .
 .Pp
-First, a spin loop
+First, on SMP systems, a spin loop
 is performed, where the library attempts to acquire the lock by
 .Xr atomic 9
 operations.