Re: impossible mission

On Fri, Jul 27 2007, ljzhang,Yaxin Hu,Jianchao Tang wrote:
> 1. The mission is defined like this:
> ----------filesize----------------
> [global]
> directory=./temp
> nrfiles=2
> rw=randread
> filesize=32k
> size=96k
> thread
> [filesize]
> description="Filesize less than size."
> ----------------------------------
>
> This job file caused another non-stop thread, which was asked to read
> 96K but only provided two files of 32K each. The running information
> kept looking like this:
> ---------------------------------
> nonggia_at_nonggia-desktop:~/fio$ fio --version
> fio 1.16.9
> nonggia_at_nonggia-desktop:~/fio$ fio filesize
> filesize: (g=0): rw=randread, bs=4K-4K/4K-4K, ioengine=sync, iodepth=1
> Starting 1 thread
> Jobs: 1 (f=2): [r] [66.7% done] [ 0/ 0 kb/s] [eta 00m:51s]
> ---------------------------------
>
> 2. The reason:
> After having covered both the two files, the thread still had 32K to
> issued, while there were already no available files on hand.
> I agree that it is far from a bug.Maybe it was the job file that we
> should blame. It was wrong written from the beginning.But why not make
> it more gentle if we can?
>
> 3. Fix suggestion:
> So what about change it like this?
> Just limit the max td->o.size with the total_size that all the files can
> provide.
> ---------------------------------
> diff -Nraup fio-7.25/filesetup.c fio-7.25-filesize/filesetup.c
> --- fio-7.25/filesetup.c 2007-07-25 14:25:05.000000000 +0800
> +++ fio-7.25-filesize/filesetup.c 2007-07-27 14:17:39.000000000 +0800
> @@ -414,7 +414,7 @@ int setup_files(struct thread_data *td)
> }
> }
>
> - if (!td->o.size)
> + if (!td->o.size || td->o.size > total_size)
> td->o.size = total_size;
>
> /*
> ---------------------------------
>
> Now it behaves like this, just finishes as much job as it can and comes
> to the end:
> ---------------------------------
> nonggia_at_nonggia-desktop:~/fio$ ./filesize_fio filesize
> filesize: (g=0): rw=randread, bs=4K-4K/4K-4K, ioengine=sync, iodepth=1
> Starting 1 thread
>
> filesize: (groupid=0, jobs=1): err= 0: pid=8045
> Description : ["Filesize less than size."]
> read : io=64KiB, bw=32768KiB/s, iops=8000, runt= 2msec
> clat (usec): min= 72, max= 907, avg=167.56, stdev=210.90
> cpu : usr=0.00%, sys=0.00%, ctx=1
> 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): 100=62.50%, 250=25.00%, 500=6.25%, 1000=6.25%
>
>
> Run status group 0 (all jobs):
> READ: io=64KiB, aggrb=32768KiB/s, minb=32768KiB/s, maxb=32768KiB/s,
> mint=2msec, maxt=2msec
>
> Disk stats (read/write):
> sda: ios=16/0, merge=0/0, ticks=0/0, in_queue=0, util=0.00%
> nonggia_at_nonggia-desktop:~/fio$
> ---------------------------------

Lovely, thanks for the fix, applied!

-- 
Jens Axboe