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Subject: Re: [MTT devel] More GDS questions
From: Andrew Senin (as_at_[hidden])
Date: 2010-02-12 11:36:16

Hello Jeff,


I would also like to add to Igor's comment that CPU time shown by Google is
a sum of all CPUs of distributed system involved in update operation (and
who knows how many servers are involved?). Also they "define 'CPU hour' in
terms of a hypothetical 1.4 GHz processor, whereas the actual processors we
use in production vary but are generally faster than this" (see comment of
9f18638b7bbea9?pli=1). According to the same topic 6.5 CPU hours is about
2.3 minutes real time. I think you may try to remove some of indexes which
need to be updated on each new file upload (see Datastore Indexes on Web
admin console).



Andrew Senin.


From: Igor Ivanov [mailto:igor.ivanov_at_[hidden]]
Sent: Friday, February 12, 2010 6:02 PM
To: Jeff Squyres
Cc: Development list for the MPI Testing Tool; bg_at_[hidden]; Yiftah
Subject: Re: More GDS questions


Hi Jeff,

You touched a sore point. App engine forums are in filled the questions as
I can not know clear answer now.


Jeff Squyres wrote:

Igor et al. --
1. I'm not sure you saw Ethan's and my posts from the past day or so about
GDS on the mtt-devel list; it just occurred to me that I don't know if
you're members of the list or not. We've posted a few questions and
comments that you may not have received if you're not on the list:
2. I'm still looking into the perl syntax error that caused my Big Submit to
GDS to fail. But looking at the Google logs, it looks like at least *some*
of my test run results made it up to GDS. There was a BIG spike in CPU
usage (3.2 hours of CPU time!) when it submitted -- see the attached CPU
usage graph from the apps dashboard.
Does anyone know why it takes so much CPU just to submit data to GDS? 3.2
CPU hours is a LOT!
It makes me a bit concerned that only part of a single Cisco MTT run submit
checked through almost half of our daily CPU quota (6.5 CPU hours/day). Is
there any way to reduce the amount of CPU necessary just to submit data?




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