Fio 3.17

[fio.git] / fio.1

diff --git a/fio.1 b/fio.1
index aaa3e99f2b74f7c85cff4f6685c12c802cbc8925..14569e9fb3dfc4d2fee552549da470768f4accfe 100644 (file)
--- a/fio.1
+++ b/fio.1
@@ -943,6 +943,10 @@ Pre-allocate via \fBposix_fallocate\fR\|(3).
 Pre-allocate via \fBfallocate\fR\|(2) with
 FALLOC_FL_KEEP_SIZE set.
 .TP
+.B truncate
+Extend file to final size using \fBftruncate\fR|(2)
+instead of allocating.
+.TP
 .B 0
 Backward-compatible alias for \fBnone\fR.
 .TP
@@ -953,7 +957,15 @@ Backward-compatible alias for \fBposix\fR.
 May not be available on all supported platforms. \fBkeep\fR is only available
 on Linux. If using ZFS on Solaris this cannot be set to \fBposix\fR
 because ZFS doesn't support pre-allocation. Default: \fBnative\fR if any
-pre-allocation methods are available, \fBnone\fR if not.
+pre-allocation methods except \fBtruncate\fR are available, \fBnone\fR if not.
+.P
+Note that using \fBtruncate\fR on Windows will interact surprisingly
+with non-sequential write patterns. When writing to a file that has
+been extended by setting the end-of-file information, Windows will
+backfill the unwritten portion of the file up to that offset with
+zeroes before issuing the new write. This means that a single small
+write to the end of an extended file will stall until the entire
+file has been filled with zeroes.
 .RE
 .TP
 .BI fadvise_hint \fR=\fPstr
@@ -2411,7 +2423,7 @@ Each job will get a unique CPU from the CPU set.
 .RE
 .P
 \fBshared\fR is the default behavior, if the option isn't specified. If
-\fBsplit\fR is specified, then fio will will assign one cpu per job. If not
+\fBsplit\fR is specified, then fio will assign one cpu per job. If not
 enough CPUs are given for the jobs listed, then fio will roundrobin the CPUs
 in the set.
 .RE