I know I'm a bit late to this conversation. Been too busy to lurk here
lately. But I wanted to respond to this comment:
Lastly Jason mentioned IncludeOS http://www.includeos.org/
these gusy are implementing something I have tossed about on this list
in the past - running applications in a lightweight OS without all the
overhead of a multitasking system.
I dont know that much about it - is anyone from that company on the list?
Lightweight operating systems for HPC is definitely a thing the IBM Blue
Gene systems used a lightweight kernel called CNK (Compute Node Kernel).
While not based on Linux, it used a subset of the Linux system call API
for its own system calls portability reasons. It was single-tasking,
since for an HPC job on a system like the Blue Gene (no node sharing
between jobs), there was no need to manage multiple tasks.
https://en.wikipedia.org/wiki/CNK_operating_system
I don't know much about Compute Node Linux (CNL), which is used on Cray
systems. I believe it is a stripped down version of Linux, but not sure
how stripped down it is.
https://en.wikipedia.org/wiki/Compute_Node_Linux
Here's some links to more information/other lightweight kernels, like
Puma and Catamount, in no particular order.
https://www.cresta-project.eu/images/WhitePapers/cresta_whitepaper_2_2014.pdf
https://ieeexplore.ieee.org/document/323279
https://www.researchgate.net/publication/228816883_Software_architecture_of_the_light_weight_kernel_Catamount
https://en.wikipedia.org/wiki/Lightweight_Kernel_Operating_System
Prentice
On 09/09/2018 11:50 PM, John Hearns via Beowulf wrote:
Chris Samuels recent post reminds me.
I went to a fascinating and well delivered talk by Jason Hearne McGuiness
https://www.meetup.com/ACCULondon/events/253570550/
https://accu.org/index.php/accu_branches/accu_london
Slides are here:
https://github.com/acculondon/2018-September
I would encourage everyone to give this presentation at least a browse.
Jason has done a lot of work in comparing the assembler code emitted
by C++ compilers for simple statement blocks. Even within the g++
series there are wildly different assembler sequences emitted. And of
course differences between Intel and Clang.
I would have naively assumed that within g+++ at least as improvements
are made then there would be some commonality - ie an evolution. But I
would be wrong.
Jason work in HFT so the default path loaded in IF statements (for
instance) is important for low latency.
Jason also did a lot of work in comparing performance before and after
the Spectre/Meltdown fixes. There is a huge amount of work gone into
that.
One other takeaway - the choice of Linux OS is critical. Really.
Common wisdom is that OS choice accounts for approx. 4% of performance
difference.
Not so.
There isa big difference between CentOS 6 and 7 (7 being better) and
Ubuntu does not shine at all well on his FIX benchmarks. Gentoo does
well - Jason being a fan of Gentoo.
As I remember on these benchmarks OS choice can affect results by 20% !!!!
Lastly Jason mentioned IncludeOS http://www.includeos.org/
these gusy are implementing something I have tossed about on this list
in the past - running applications in a lightweight OS without all the
overhead of a multitasking system.
I dont know that much about it - is anyone from that company on the list?
John Hearns
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