svn commit: r219801 - head/sys/kern

Alan Cox alc at FreeBSD.org
Sun Mar 20 15:04:43 UTC 2011


Author: alc
Date: Sun Mar 20 15:04:43 2011
New Revision: 219801
URL: http://svn.freebsd.org/changeset/base/219801

Log:
  Update a comment.  The sending process has not mapped the buffer pages
  since before r127501.  Strictly speaking, the buffer pages are not
  "wired".  They remain in the paging queues.  However, they are pinned in
  memory using vm_page_hold().

Modified:
  head/sys/kern/sys_pipe.c

Modified: head/sys/kern/sys_pipe.c
==============================================================================
--- head/sys/kern/sys_pipe.c	Sun Mar 20 14:12:50 2011	(r219800)
+++ head/sys/kern/sys_pipe.c	Sun Mar 20 15:04:43 2011	(r219801)
@@ -29,9 +29,9 @@
  * write mode.  The small write mode acts like conventional pipes with
  * a kernel buffer.  If the buffer is less than PIPE_MINDIRECT, then the
  * "normal" pipe buffering is done.  If the buffer is between PIPE_MINDIRECT
- * and PIPE_SIZE in size, it is fully mapped and wired into the kernel, and
- * the receiving process can copy it directly from the pages in the sending
- * process.
+ * and PIPE_SIZE in size, the sending process pins the underlying pages in
+ * memory, and the receiving process copies directly from these pinned pages
+ * in the sending process.
  *
  * If the sending process receives a signal, it is possible that it will
  * go away, and certainly its address space can change, because control


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