Setting number of read threads

Setting number of read threads

[Elliott Balsley]

When I do a sequential read test with multiple threads, the initial
write only uses one thread.  Is there some way to adjust this?  For
example a command like this:

fio --name moe --rw read --directory /mnt/nv01/fio/local --size 40G
--bs 4M --numjobs 4 --group_reporting --direct 1

It lays out four files one at a time, then it reads them all back at
once.  I would like to lay out the four files simultaneously to save
time.  I hope this makes sense; I'm not sure if I'm phrasing this in
the right way.

Re: Setting number of read threads

[Jens Axboe]

On 2/26/20 2:32 PM, Elliott Balsley wrote:
> When I do a sequential read test with multiple threads, the initial
> write only uses one thread.  Is there some way to adjust this?  For
> example a command like this:
> 
> fio --name moe --rw read --directory /mnt/nv01/fio/local --size 40G
> --bs 4M --numjobs 4 --group_reporting --direct 1
> 
> It lays out four files one at a time, then it reads them all back at
> once.  I would like to lay out the four files simultaneously to save
> time.  I hope this makes sense; I'm not sure if I'm phrasing this in
> the right way.

create_serialize=false would do that. It defaults to sequentially
since otherwise the fs layout tends to suffer.

-- 
Jens Axboe