Adrian,
Ah, OK. I'm familiar with the balanced system concept in general, but I wasn't
familiar with the specific formalisms (particularly Amdahl's set of rules) described
in that slide deck. Thanks!
And, yes, I would say I agree with you here - IO500 is specifically an IO subsystem
benchmark, not intended to evaluate any other aspect of the system. It could be
*combined* with other data, but collecting that other data is outside the intended scope.
I'd say this is because how to do that general compute benchmarking is a hugely
complex and contentious issue, and also because IO500 is useful specifically because
it's bounded in its scope.
- Patrick
________________________________
From: JACKSON Adrian <a.jackson(a)epcc.ed.ac.uk>
Sent: Saturday, August 10, 2019 11:53:16 AM
To: Patrick Farrell <pfarrell(a)whamcloud.com>; Puneet Bakshi
<b.puneet(a)iitg.ac.in>
Cc: io-500(a)vi4io.org <io-500(a)vi4io.org>
Subject: Re: [IO-500] Why "Amdahl IO no" is not part of IO500 metric?
Hi Patrick,
This is a reasonable intro to the balanced system concept:
https://www-conf.slac.stanford.edu/xldb10/docs/xldb4_thu1040_AlexSzalay.pdf
I think the answer really is that the IO500 is specifically an I/O
metric/benchmark, it's not designed to be a whole system thing.
Not to say there isn't merit in collecting whole system data like this,
i.e. something like a combined top500/hpcg/streams/io500, it's just not
what the io500 was designed for.
cheers
adrianj
On 10/08/2019 17:37, Patrick Farrell via IO-500 wrote:
Puneet,
I am familiar with Amdahl’s Law, but I am not familiar with Amdahl IO
and cannot find anything with Google. Do you have a reference for this,
explaining how it’s computed and what it’s supposed to mean? It is hard
to see how the Amdahl’s Law - that speed up from parallelism is limited
by the serial portion of a program - has any relationship to the I/O 500
benchmarks, which are concerned with a series of specific and separate
benchmarks. The various benchmark numbers are not part of a single
parallel program, and so do not have the sort of relationship where
Amdahl’s Law is relevant.
Regards,
Patrick
------------------------------------------------------------------------
*From:* IO-500 <io-500-bounces(a)vi4io.org> on behalf of Puneet Bakshi via
IO-500 <io-500(a)vi4io.org>
*Sent:* Friday, August 9, 2019 11:11:47 PM
*To:* io-500(a)vi4io.org <io-500(a)vi4io.org>
*Subject:* [IO-500] Why "Amdahl IO no" is not part of IO500 metric?
Dear Sir/Madam,
I am Puneet from India and is a student in Indian Institute of
Technology Guwahati.
I read about IO500 and (Amdahl) Balanced Systems (such as GrayWulf).
But, after doing some math, I found some of the top IO500 systems have
very low Amdahl IO number. Why IO500 does not include (and publish)
Amdahl IO number as one of its metric? Looks like I am missing something
but I do not know what. Please help me understand this paradox. This
question just came out as an academic curiosity and not to endorse or
refute any system. Please help me understand more.
Regards,
Puneet
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