* Using offsets in fio
@ 2010-04-27 0:19 Michael O'Sullivan
2010-04-27 6:42 ` Jens Axboe
0 siblings, 1 reply; 4+ messages in thread
From: Michael O'Sullivan @ 2010-04-27 0:19 UTC (permalink / raw)
To: fio; +Cc: DongJin Lee
Hi everyone,
We are using fio to emulate the SPC-1 benchmark (we hope to get this
included as a --profile in fio in the not too distant future). However,
we have noticed that when running our benchmark the disk we are testing
does not seem to be overly busy seeking to different locations on the
disk. When we run tests using Iometer we can hear the disk seeking to
different sections of the disk pretty much the whole time. We are using
io_u->offset to define the position in the file we wish to read/write
at, but it is not clear to us whether this is having the desired effect.
It doesn't seem so at this point... We have been using the sync and
libaio engines.
Can someone please give us some advice to help us troubleshoot this
problem? Or point us to a tool that will let us see where fio is
reading/writing on the disk? Any help is greatly appreciated.
Kind regards, Mike
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: Using offsets in fio
2010-04-27 0:19 Using offsets in fio Michael O'Sullivan
@ 2010-04-27 6:42 ` Jens Axboe
2010-04-27 6:49 ` DongJin Lee
0 siblings, 1 reply; 4+ messages in thread
From: Jens Axboe @ 2010-04-27 6:42 UTC (permalink / raw)
To: Michael O'Sullivan; +Cc: fio, DongJin Lee
On Tue, Apr 27 2010, Michael O'Sullivan wrote:
> Hi everyone,
>
> We are using fio to emulate the SPC-1 benchmark (we hope to get this
> included as a --profile in fio in the not too distant future). However,
> we have noticed that when running our benchmark the disk we are testing
> does not seem to be overly busy seeking to different locations on the
> disk. When we run tests using Iometer we can hear the disk seeking to
> different sections of the disk pretty much the whole time. We are using
> io_u->offset to define the position in the file we wish to read/write
> at, but it is not clear to us whether this is having the desired effect.
> It doesn't seem so at this point... We have been using the sync and
> libaio engines.
io_u->offset is the byte offset that the engine will seek to before
performing IO, so whatever you put in there will be the real offset. If
the disk doesn't sound as busy as it should, perhaps it's because
iometer drives a higher queue depth as well?
> Can someone please give us some advice to help us troubleshoot this
> problem? Or point us to a tool that will let us see where fio is
> reading/writing on the disk? Any help is greatly appreciated.
For shorter samples, you could always just strace fio and see what it's
doing. For a better view, you could use blktrace.
--
Jens Axboe
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: Using offsets in fio
2010-04-27 6:42 ` Jens Axboe
@ 2010-04-27 6:49 ` DongJin Lee
2010-04-27 6:54 ` Jens Axboe
0 siblings, 1 reply; 4+ messages in thread
From: DongJin Lee @ 2010-04-27 6:49 UTC (permalink / raw)
To: Jens Axboe; +Cc: Michael O'Sullivan, fio
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So for example, you'd expect, for example,
at the end of 1TB position (1073741824 bytes) the offset is to be 1073741824
?
and similarly for end of 2TB position, the offset would be the twice?
Regards
On Tue, Apr 27, 2010 at 6:42 PM, Jens Axboe <jens.axboe@oracle.com> wrote:
> On Tue, Apr 27 2010, Michael O'Sullivan wrote:
> > Hi everyone,
> >
> > We are using fio to emulate the SPC-1 benchmark (we hope to get this
> > included as a --profile in fio in the not too distant future). However,
> > we have noticed that when running our benchmark the disk we are testing
> > does not seem to be overly busy seeking to different locations on the
> > disk. When we run tests using Iometer we can hear the disk seeking to
> > different sections of the disk pretty much the whole time. We are using
> > io_u->offset to define the position in the file we wish to read/write
> > at, but it is not clear to us whether this is having the desired effect.
> > It doesn't seem so at this point... We have been using the sync and
> > libaio engines.
>
> io_u->offset is the byte offset that the engine will seek to before
> performing IO, so whatever you put in there will be the real offset. If
> the disk doesn't sound as busy as it should, perhaps it's because
> iometer drives a higher queue depth as well?
>
> > Can someone please give us some advice to help us troubleshoot this
> > problem? Or point us to a tool that will let us see where fio is
> > reading/writing on the disk? Any help is greatly appreciated.
>
> For shorter samples, you could always just strace fio and see what it's
> doing. For a better view, you could use blktrace.
>
> --
> Jens Axboe
>
>
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^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: Using offsets in fio
2010-04-27 6:49 ` DongJin Lee
@ 2010-04-27 6:54 ` Jens Axboe
0 siblings, 0 replies; 4+ messages in thread
From: Jens Axboe @ 2010-04-27 6:54 UTC (permalink / raw)
To: DongJin Lee; +Cc: Michael O'Sullivan, fio
On Tue, Apr 27 2010, DongJin Lee wrote:
> So for example, you'd expect, for example,
> at the end of 1TB position (1073741824 bytes) the offset is to be 1073741824
> ?
1073741824 byte offset would be 1GB.
> and similarly for end of 2TB position, the offset would be the twice?
Yeah, there's no magic there, it's simply a byte offset where the IO
will take place.
--
Jens Axboe
^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2010-04-27 6:54 UTC | newest]
Thread overview: 4+ messages (download: mbox.gz / follow: Atom feed)
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2010-04-27 0:19 Using offsets in fio Michael O'Sullivan
2010-04-27 6:42 ` Jens Axboe
2010-04-27 6:49 ` DongJin Lee
2010-04-27 6:54 ` Jens Axboe
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