[src/trunk]: src/share/man/man9 Explain resource estimation bug in wapbl(9).

[riastradh <riastradh%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/109804a32c00
branches:  trunk
changeset: 336935:109804a32c00
user:      riastradh <riastradh%NetBSD.org@localhost>
date:      Fri Mar 27 21:50:39 2015 +0000

description:
Explain resource estimation bug in wapbl(9).

diffstat:

 share/man/man9/wapbl.9 |  11 ++++++++++-
 1 files changed, 10 insertions(+), 1 deletions(-)

diffs (25 lines):

diff -r d23867cef38b -r 109804a32c00 share/man/man9/wapbl.9
--- a/share/man/man9/wapbl.9    Fri Mar 27 21:41:32 2015 +0000
+++ b/share/man/man9/wapbl.9    Fri Mar 27 21:50:39 2015 +0000
@@ -1,4 +1,4 @@
-.\"    $NetBSD: wapbl.9,v 1.6 2015/03/27 21:41:32 riastradh Exp $
+.\"    $NetBSD: wapbl.9,v 1.7 2015/03/27 21:50:39 riastradh Exp $
 .\"
 .\" Copyright (c) 2015 The NetBSD Foundation, Inc.
 .\" All rights reserved.
@@ -444,6 +444,15 @@
 .Xr fsck 8
 to work.
 .Pp
+The criteria for when the transaction must be flushed to disk before
+.Fn wapbl_begin
+returns are heuristic, i.e. wrong.
+There is no way for a file system to communicate to
+.Fn wapbl_begin
+how many buffers, inodes, and deallocations it will issue via
+.Nm
+in the transaction.
+.Pp
 There is only one
 .Nm
 transaction for each file system at any given time, and only one