Capturing I/O traces

[Victor Loureiro Lima]

Maybe you could take a look at iostat(8), seems to be able to help you
somehow!!! ;)

att,
victor loureiro lima

2007/1/9, Fluffles <etc at fluffles.net>:
> Ivan Voras wrote:
> > Fluffles wrote:
> >
> >
> >> One thought that comes to mind is the gnop geom class; with verbose mode
> >> this provides a text log of all the I/O accesses. But it does not
> >> provide the exact time/concurrency etc, only the offset, length, I/O
> >>
> >
> > What do you mean by "time" and "concurrency"? You do realize that
> > requests are serialized on the low level?
> >
>
> Sure but simply capturing the serial order of requests might not be
> sufficient. For example: the application might 'wait' for one request to
> be finished because it needs that data in order to do another I/O
> request. I guess this is the hard part. If i would just execute the I/O
> in a serial way things like accesstime or 'latency' are less important
> because the overall throughput counts; while this may not be true for
> real applications but they might wait on one request before they can
> move on; thus a lower latency might be more important than a higher
> throughput.
>
> I guess it's not easy to really make something like this be reliable and
> realistic, but i'd like to come as close as possible. For example, the
> website StorageReview also uses traces to benchmark specific uses, two
> links:
>
> http://www.storagereview.com/articles/200611/ST3750640NS_3.html
> http://www.storagereview.com/articles/200510/Testbed4_4.html
>
> I'd like to use traces of applications on FreeBSD (or GNU/Linux) to
> benchmark KDE startup, MySQL, Apache and other applications. So i can
> have benchmark suites like "desktop", "webserver" and "database". That
> would be very neat.
>
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