Re: non-stop thread in fio-1.16.9

On Thu, Jul 26 2007, ljzhang,Yaxin Hu,Jianchao Tang wrote:
> 1. The job file causing the problem:
> -------------------rw-------------------
> [global]
> directory=./temp
> nrfiles=1
> rw=randread:8
> norandommap
> size=32k
> bs=2k
> thread
> [rw]
> description="Offset over real file size."
> -----------------------------------------
>
> The job file can keep fio running with the eta increasing and the
> progress pausing like this:
> ----------------------------------------
> rw: (g=0): rw=randread, bs=2K-2K/2K-2K, ioengine=sync, iodepth=1
> Starting 1 thread
> Jobs: 1 (f=1): [r] [92.3% done] [ 0/ 0 kb/s] [eta 00m:01s]]
>
> ----------------------------------------
>
> If we force it to stop, it prints like this:
> --------------------------------------------
> fio: terminating on signal 2
>
> rw: (groupid=0, jobs=1): err= 0: pid=6124
> Description : ["Offset over real file size."]
> read : io=28KiB, bw=0KiB/s, iops=0, runt= 61900msec
> clat (usec): min= 5, max= 436, avg=87.79, stdev=123.71
> cpu : usr=2.01%, sys=93.48%, ctx=13644
> IO depths : 1=100.0%, 2=0.0%, 4=0.0%, 8=0.0%, 16=0.0%, 32=0.0%,
> >=64=0.0%
> issued r/w: total=14/0, short=0/0
> lat (usec): 10=42.86%, 100=35.71%, 250=7.14%, 500=14.29%
>
>
> Run status group 0 (all jobs):
> READ: io=28KiB, aggrb=0KiB/s, minb=0KiB/s, maxb=0KiB/s,
> mint=61900msec, maxt=61900msec
>
> Disk stats (read/write):
> sda: ios=8/45, merge=0/40, ticks=4/368, in_queue=372, util=0.27%
> --------------------------------------------
> >From above we can see an uncompleted job with a io 28KiB less than what
> is specified by 'size'.
>
> 2. Reason for problem:
> After looking into the source codes,We guess the problem comes from the
> function get_next_offset().If the io reaches the end of the file, the
> function fails, and the file will be marked as DONE.We wonder if that is
> the planned behavior.Isn't it very common to reach the file's end when
> doing a random io?
>
> 3. Fix suggestion:
> Here is the patch:
> -----------------------------------------------------
> diff -Nraup fio-7.25/io_u.c fio-7.25-rw/io_u.c
> --- fio-7.25/io_u.c 2007-07-25 14:25:05.000000000 +0800
> +++ fio-7.25-rw/io_u.c 2007-07-26 09:55:22.000000000 +0800
> @@ -162,10 +162,12 @@ static int get_next_offset(struct thread
> if (get_next_rand_offset(td, f, ddir, &b))
> return 1;
> } else {
> - if (f->last_pos >= f->real_file_size)
> - return 1;
> -
> - b = f->last_pos / td->o.min_bs[ddir];
> + if (f->last_pos >= f->real_file_size) {
> + if (!td_random(td) || get_next_rand_offset(td, f, ddir, &b))
> + return 1;
> + } else {
> + b = f->last_pos / td->o.min_bs[ddir];
> + }
> }
>
> io_u->offset = (b * td->o.min_bs[ddir]) + f->file_offset;
> ------------------------------------------------------
>
> After applying that, we got the job file run to the end normally:
> -------------------------------------------------------
> nonggia_at_nonggia-desktop:~/fio$ ./rw_fio rw
> rw: (g=0): rw=randread, bs=2K-2K/2K-2K, ioengine=sync, iodepth=1
> Starting 1 thread
>
> rw: (groupid=0, jobs=1): err= 0: pid=6519
> Description : ["Offset over real file size."]
> read : io=32KiB, bw=1560KiB/s, iops=761, runt= 21msec
> clat (usec): min= 5, max=14251, avg=1293.50, stdev=3510.37
> cpu : usr=0.00%, sys=19.05%, ctx=7
> IO depths : 1=100.0%, 2=0.0%, 4=0.0%, 8=0.0%, 16=0.0%, 32=0.0%,
> >=64=0.0%
> issued r/w: total=16/0, short=0/0
> lat (usec): 10=37.50%, 20=12.50%, 250=12.50%, 750=6.25%, 1000=6.25%
> lat (msec): 2=18.75%, 20=6.25%
>
> Run status group 0 (all jobs):
> READ: io=32KiB, aggrb=1560KiB/s, minb=1560KiB/s, maxb=1560KiB/s,
> mint=21msec, maxt=21msec
>
> Disk stats (read/write):
> sda: ios=8/0, merge=0/0, ticks=20/0, in_queue=20, util=13.89%
> -------------------------------------------------------

Thanks again, applied!

-- 
Jens Axboe