Ending condition for non-rr file service

Ending condition for non-rr file service

[Travis Downs]

I guess I understand when fio "stops" when using 1 file per job: after
`io_size` IOs,
which is usually the same as `size` if `io_size` has not been
specified explicitly.

When size == io_size, this means that all blocks of the files are
written exactly once
with linear or random writes, except if norandmap=1, in which case
some blocks will
likely be written 0 times and others 2 or more times.

How does this work for nrfiles > 1 and linear writes (rw=write) and
file_service_type
set to one of the random ones? For the non-uniform distributions some
files will be
written at a higher rate than others: does the write pointer just loop
when it gets to
the end of the file? So io_size writes will still be done, but some
files will not be
completely written while others may be written more than once?

Travis

Re: Ending condition for non-rr file service

[Vincent Fu]

On 5/26/23 11:38, Travis Downs wrote:
 > I guess I understand when fio "stops" when using 1 file per job: after
 > `io_size` IOs,
 > which is usually the same as `size` if `io_size` has not been
 > specified explicitly.
 >
 > When size == io_size, this means that all blocks of the files are
 > written exactly once
 > with linear or random writes, except if norandmap=1, in which case
 > some blocks will
 > likely be written 0 times and others 2 or more times.
 >
 > How does this work for nrfiles > 1 and linear writes (rw=write) and
 > file_service_type
 > set to one of the random ones? For the non-uniform distributions some
 > files will be
 > written at a higher rate than others: does the write pointer just loop
 > when it gets to
 > the end of the file? So io_size writes will still be done, but some
 > files will not be
 > completely written while others may be written more than once?
 >
 > Travis
Fio's behavior in this situation is not explicitly spelled out in the 
documentation.

For a job with a single file, fio will just start over again and write 
the file multiple times when io_size > filesize. I would expect the same 
to happen when nrfiles > 1.

Try a run with --debug=io,file and let us know!

Vincent