I did do some testing with the original round of updates and I found the 
supplementary GPFS monitoring tools (mmsysmon) written in Python were having a 
profoundly negative affect on performance with the Spectre/Meltdown patches 
with even first pass things like Linpack. You can disable the supplementary 
monitoring though and that cleared up the performance issues I was seeing. I 
didn't get very deep into it before they retracted all the firmware updates and 
we decided to wait and see. IBM had talked about providing options to make the 
querying less intrusive and less frequent on the GPFS UG mailing list in newer 
versions of GPFS as well.

Stephen

________________________________________
From: Beowulf <beowulf-boun...@beowulf.org> on behalf of Ryan Novosielski 
<novos...@rutgers.edu>
Sent: Thursday, March 8, 2018 12:55:34 PM
To: Beowulf List
Subject: Re: [Beowulf] Update on dealing with Spectre and Meltdown

I have been waiting, specifically, for Prentice Bisbal to try it. :-P

I actually have not checked to see whether any other upgrades I’ve applied have 
handled these vulnerabilities (I’d assume RedHat would have patched their 
distribution). FWIW, however, I did receive a report that one of our newer 
images seemed slower.  Haven’t gotten a chance to fully investigate those 
reports — could be any number of other things.

--
____
|| \\UTGERS,       |---------------------------*O*---------------------------
||_// the State     |         Ryan Novosielski - 
novos...@rutgers.edu<mailto:novos...@rutgers.edu>
|| \\ University | Sr. Technologist - 973/972.0922 (2x0922) ~*~ RBHS Campus
||  \\    of NJ     | Office of Advanced Research Computing - MSB C630, Newark
    `'

On Mar 8, 2018, at 13:13, Alex Chekholko via Beowulf 
<beowulf@beowulf.org<mailto:beowulf@beowulf.org>> wrote:

As an experienced and cynical HPC admin working with trusted users... I have 
not installed any kind of firmware or kernel updates.  I'll wait for you to go 
first :)

On Thu, Mar 8, 2018 at 10:10 AM, Prentice Bisbal 
<pbis...@pppl.gov<mailto:pbis...@pppl.gov>> wrote:
Beowulfers,

Have any of you updated the kernels on your clusters to fix the Spectre and 
Meltdown vulnerabilities? I was following this issue closely for the first 
couple of weeks. There seemed to be a lack of consensus on how much these fixed 
would impact HPC jobs, and if I recall correctly, some of the patches really 
hurt performance, or caused other problems. We took a wait-and-see approach 
here. So now that I've waited a while, what did you see?

--
Prentice

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