Flexible I/O Tester development
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From: Alex Pyrgiotis <apyrgio@grnet.gr>
To: Juan Casse <jcasse@chromium.org>
Cc: "fio@vger.kernel.org" <fio@vger.kernel.org>
Subject: Re: Using LFSR
Date: Tue, 20 Aug 2013 10:37:41 +0300	[thread overview]
Message-ID: <52131CC5.9020508@grnet.gr> (raw)
In-Reply-To: <CAPet_21dehFMKwU25L+ho1uRWOO6w_p7LqxxyJe5gQ5a9G0M5A@mail.gmail.com>

On 08/20/2013 02:11 AM, Juan Casse wrote:
> Hi,
> 
> How is LFSR used?
> 
> When running the job file:
> 
> [global]
> readwrite=randwrite
> size=64k
> bs=8192
> random_generator=lfsr
> [test_job]
> 
> fio returns:
> 
> "fio: failed allocating random map. If running a large number of jobs,
> try the 'norandommap' option or set 'softrandommap'. Or give a larger
> --alloc-size to fio."
> 
> I tried the recommendations in the message above to no avail. I also
> tried other combinations of size, bs, and readwrite.

Hi Juan,

Could you provide the fio version you are using (fio -v)? I'm currently
using the latest version from git and I don't see these results.
Specifically, what I'm getting is:

-------------------------------
test_job: (g=0): rw=randwrite, bs=8K-8K/8K-8K/8K-8K, ioengine=sync,
iodepth=1
fio-2.1.2-13-g3e10
Starting 1 process
Value is 7
Value is 6
Value is 4
Value is 0
Value is 1
Value is 5
Value is 2
Value is 3

test_job: (groupid=0, jobs=1): err= 0: pid=24672: Tue Aug 20 10:27:28 2013
  write: io=65536B, bw=64000KB/s, iops=8000, runt=     1msec
    clat (usec): min=6, max=43, avg=11.50, stdev=12.75
     lat (usec): min=7, max=44, avg=11.88, stdev=12.99
    clat percentiles (usec):
<...snip...>
    lat (usec) : 10=87.50%, 50=12.50%
  cpu          : usr=0.00%, sys=0.00%, ctx=16, majf=0, minf=41
<...snip...>

Run status group 0 (all jobs):
  WRITE: io=64KB, aggrb=64000KB/s, minb=64000KB/s, maxb=64000KB/s,
mint=1msec, maxt=1msec

Disk stats (read/write):
  sda: ios=0/0, merge=0/0, ticks=0/0, in_queue=0, util=0.00%
-------------------------------

The output has been cut in some parts for readability reasons. Also, the
"Value is..." lines have been added to show which blocks fio is hitting.

Regards,
Alex

-- 
Alex | apyrgio@grnet.gr

  reply	other threads:[~2013-08-20  7:56 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2013-08-19 23:11 Using LFSR Juan Casse
2013-08-20  7:37 ` Alex Pyrgiotis [this message]
2013-08-21  0:21   ` Juan Casse
2013-08-20 14:26 ` Jens Axboe

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