On 24/05/11 18:43, [email protected] wrote:
Message: 6
Date: Tue, 24 May 2011 17:48:47 +0200
From: Reuti<[email protected]>
To: Dave Love<[email protected]>
Cc:"[email protected] Group" <[email protected]>
Subject: Re: [gridengine users] CPU = WALLCLOCK time in the share tree
policy ?
Message-ID:
<[email protected]>
Content-Type: text/plain; charset=US-ASCII; format=flowed; delsp=yes
Am 24.05.2011 um 15:35 schrieb Dave Love:
> ..._RESERVED_USAGE are at least badly documented. When I came across
> them I interpreted `reserved' to mean resource reservation, i.e. the
> overhead from doing that. I'll fix the doc; does anyone have a good
> suggestion for a better description? I'm inclined to say `available
> resources' and explain further. I haven't got round to checking,
> but I
> assume what's used for cpu is running time multiplied by slot count;
> anyone know what's used for io, which is specifically mentioned?
>
> Also, I wonder why SHARETREE_RESERVED_USAGE is deprecated, as it seems
> more useful default.
Although someone stated on the list to use it in the way:
SHARETREE_RESERVED_USAGE=FALSE
ACCT_RESERVED_USAGE=TRUE
(and hence complained about unifiying it), I think most often you will
set just both to TRUE or FALSE, and so just one setting would be
enough and imply the second.
-- Reuti
That was me, but the other way around - SHARETREE_RESERVED_USAGE=TRUE,
ACCT_RESERVED_USAGE=false.
We'd still find it useful to be able to see how much CPU time was used
on the system, as opposed to wallclock time. However, we use wallclock
time for accounting purposes, and therefore also in determining share
tree tickets.
With the above configuration, the system wasn't honouring the
ACCT_RESERVED_USAGE flag, and just reports wallclock time in the CPUTIME
field (using 6.2u5 from Sun).
There were two key reasons for wanting to be able to see the CPU time on
the system:
- some user groups (notably GridPP who process CERN work) use it as a
metric for measuring the efficiency of a given system (cpu time /
wallclock time = efficiency)
- In general, it's a useful metric to see what how your system is
being used, and where more can be squeezed out of it.
So I'd still be in favour of keeping both in! Having said that - the
value of CPU utilisation can be obtained by doing (UTIME + STIME), but
it still seems a bit odd to have a CPUTIME field which doesn't give you
CPUTIME. Especially when there's a WALLCLOCK field sitting right there
already!
If anything - I'd suggest that the ACCT_RESERVED_USAGE field could be
deprecated with respects to manipulating the data which is put into the
accounting file. I'd always prefer that the raw data goes into the
accounting file, which doesn't vary depending on configuration settings.
--
--
Dr Orlando Richards
Information Services
IT Infrastructure Division
Unix Section
Tel: 0131 650 4994
The University of Edinburgh is a charitable body, registered in
Scotland, with registration number SC005336.
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