add documentation about filename_format directory behavior

[fio.git] / HOWTO

diff --git a/HOWTO b/HOWTO
index df79e2dffb3043e771fa437f6f1845b423a41160..a1513e1259f7cc3001fb185a662150a9527dba34 100644 (file)
--- a/HOWTO
+++ b/HOWTO
@@ -217,6 +217,9 @@ Command line options
 .. option:: --max-jobs=nr
 
        Set the maximum number of threads/processes to support to `nr`.
+       NOTE: On Linux, it may be necessary to increase the shared-memory
+       limit ('/proc/sys/kernel/shmmax') if fio runs into errors while
+       creating jobs.
 
 .. option:: --server=args
 
@@ -792,6 +795,13 @@ Target file/device
        named :file:`testfiles.4`. The default of :file:`$jobname.$jobnum.$filenum`
        will be used if no other format specifier is given.
 
+       If you specify a path then the directories will be created up to the
+       main directory for the file.  So for example if you specify
+       ``filename_format=a/b/c/$jobnum`` then the directories a/b/c will be
+       created before the file setup part of the job.  If you specify
+       :option:`directory` then the path will be relative that directory,
+       otherwise it is treated as the absolute path.
+
 .. option:: unique_filename=bool
 
        To avoid collisions between networked clients, fio defaults to prefixing any