Documentation update

[fio.git] / HOWTO

diff --git a/HOWTO b/HOWTO
index 886515b7aa754527070ee24ab785d66abb5b0b3e..3e1e62a0f4d3115fa947471febf2796150eae9f2 100644 (file)
--- a/HOWTO
+++ b/HOWTO
@@ -566,11 +566,25 @@ fsync=int If writing to a file, issue a sync of the dirty data
                not sync the file. The exception is the sg io engine, which
                synchronizes the disk cache anyway.
 
-fsyncdata=int  Like fsync= but uses fdatasync() to only sync data and not
+fdatasync=int  Like fsync= but uses fdatasync() to only sync data and not
                metadata blocks.
                In FreeBSD there is no fdatasync(), this falls back to
                using fsync()
 
+sync_file_range=str:val        Use sync_file_range() for every 'val' number of
+               write operations. Fio will track range of writes that
+               have happened since the last sync_file_range() call. 'str'
+               can currently be one or more of:
+
+               wait_before     SYNC_FILE_RANGE_WAIT_BEFORE
+               write           SYNC_FILE_RANGE_WRITE
+               wait_after      SYNC_FILE_RANGE_WAIT_AFTER
+
+               So if you do sync_file_range=wait_before,write:8, fio would
+               use SYNC_FILE_RANGE_WAIT_BEFORE | SYNC_FILE_RANGE_WRITE for
+               every 8 writes. Also see the sync_file_range(2) man page.
+               This option is Linux specific.
+
 overwrite=bool If true, writes to a file will always overwrite existing
                data. If the file doesn't already exist, it will be
                created before the write phase begins. If the file exists
@@ -809,7 +823,9 @@ verify=str  If writing to a file, fio can verify the file contents
                                it in the header of each block.
 
                        crc32c-intel Use hardware assisted crc32c calcuation
-                               provided on SSE4.2 enabled processors.
+                               provided on SSE4.2 enabled processors. Falls
+                               back to regular software crc32c, if not
+                               supported by the system.
 
                        crc32   Use a crc32 sum of the data area and store
                                it in the header of each block.
@@ -885,6 +901,22 @@ verify_async=int   Fio will normally verify IO inline from the submitting
 verify_async_cpus=str  Tell fio to set the given CPU affinity on the
                async IO verification threads. See cpus_allowed for the
                format used.
+
+verify_backlog=int     Fio will normally verify the written contents of a
+               job that utilizes verify once that job has completed. In
+               other words, everything is written then everything is read
+               back and verified. You may want to verify continually
+               instead for a variety of reasons. Fio stores the meta data
+               associated with an IO block in memory, so for large
+               verify workloads, quite a bit of memory would be used up
+               holding this meta data. If this option is enabled, fio
+               will verify the previously written blocks before continuing
+               to write new ones.
+
+verify_backlog_batch=int       Control how many blocks fio will verify
+               if verify_backlog is set. If not set, will default to
+               the value of verify_backlog (meaning the entire queue
+               is read back and verified).
                
 stonewall      Wait for preceeding jobs in the job file to exit, before
                starting this one. Can be used to insert serialization
@@ -928,7 +960,7 @@ read_iolog=str      Open an iolog with the specified file name and replay the
                to replay a workload captured by blktrace. See blktrace
                for how to capture such logging data. For blktrace replay,
                the file needs to be turned into a blkparse binary data
-               file first (blktrace <device> -d file_for_fio.bin).
+               file first (blkparse <device> -o /dev/null -d file_for_fio.bin).
 
 write_bw_log=str If given, write a bandwidth log of the jobs in this job
                file. Can be used to store data of the bandwidth of the
@@ -1022,6 +1054,12 @@ cgroup_weight=int        Set the weight of the cgroup to this value. See
                the documentation that comes with the kernel, allowed values
                are in the range of 100..1000.
 
+cgroup_nodelete=bool Normally fio will delete the cgroups it has created after
+               the job completion. To override this behavior and to leave
+               cgroups around after the job completion, set cgroup_nodelete=1.
+               This can be useful if one wants to inspect various cgroup
+               files after job completion. Default: false
+
 uid=int                Instead of running as the invoking user, set the user ID to
                this value before the thread/process does any work.