From 5b42a488b1e3be03ecec9305affbbabaa2f2134e Mon Sep 17 00:00:00 2001 From: Stefan Hajnoczi Date: Sat, 8 Jan 2011 20:28:41 +0100 Subject: [PATCH] Document that write_iolog is unsafe for concurrent jobs The write_iolog parameter should not be used in the global section since each job will independently write to the same file. The output will be interspersed and the file will be corrupt. Document that each job should write to its own iolog file. This will save users time when trying out the iolog feature for the first time. Signed-off-by: Stefan Hajnoczi Updated by me to make the same change to the man page. Signed-off-by: Jens Axboe --- HOWTO | 3 ++- README | 4 +++- fio.1 | 4 +++- 3 files changed, 8 insertions(+), 3 deletions(-) diff --git a/HOWTO b/HOWTO index dc21afc0..7c943294 100644 --- a/HOWTO +++ b/HOWTO @@ -988,7 +988,8 @@ zoneskip=int Skip the specified number of bytes when zonesize data has io on zones of a file. write_iolog=str Write the issued io patterns to the specified file. See - read_iolog. + read_iolog. Specify a separate file for each job, otherwise + the iologs will be interspersed and the file may be corrupt. read_iolog=str Open an iolog with the specified file name and replay the io patterns it contains. This can be used to store a diff --git a/README b/README index 0f91c66f..de06fb10 100644 --- a/README +++ b/README @@ -274,7 +274,9 @@ The job file parameters are: and length entries being in bytes. write_iolog=x Write an iolog to file 'x' in the same format as iolog. The iolog options are exclusive, if both given the - read iolog will be performed. + read iolog will be performed. Specify a separate file + for each job, otherwise the iologs will be interspersed + and the file may be corrupt. write_bw_log Write a bandwidth log. write_lat_log Write a latency log. lockmem=x Lock down x amount of memory on the machine, to diff --git a/fio.1 b/fio.1 index eaa1c408..1f1116c9 100644 --- a/fio.1 +++ b/fio.1 @@ -743,7 +743,9 @@ Skip the specified number of bytes when \fBzonesize\fR bytes of data have been read. .TP .BI write_iolog \fR=\fPstr -Write the issued I/O patterns to the specified file. +Write the issued I/O patterns to the specified file. Specify a separate file +for each job, otherwise the iologs will be interspersed and the file may be +corrupt. .TP .BI read_iolog \fR=\fPstr Replay the I/O patterns contained in the specified file generated by -- 2.25.1