<HTML><BODY>
<br />
<br />
I am running Centos 6, I wish to tweak something under /sys on boot, what is the<BR>
best way of doing it ?<BR>
<BR>
If I want to initialise something under /proc I can put it into /etc/sysctl.conf<BR>
--- is there something equivalent for /sys ?<BR>
<BR>
OK: I can always write my own init script, but ....<BR>
<BR>
What I want to achieve is:<BR>
<BR>
echo 1 > /sys/devices/system/cpu/sched_smt_power_savings<BR>
<BR>
On SuSE systems you would consider putting this in /etc/init.d/boot.local<BR>
<BR>
which will:<BR>
<BR>
One core will be filled with tasks before tasks will be moved to other<BR>
cores. The idea is to concentrate the running tasks on a relatively small<BR>
number of cores, allowing the others to remain idle.<BR>
<BR>
Funnily enough, you do exactly the opposite in HPC (high performance computing.<BR>
In an optimal situation, your code will run at (you hope) 100% of a core.<BR>
So you match the number of processes you run per node with the core count, and use NUMA tools<BR>
to place each process on a core.<BR>
Actually, it CAN give you performance gains in multi-core processors to run on alternate cores,<BR>
Eg. If hyperthreading is enabled or if cores share a cache.<BR>
<BR>
<BR>
If you're looking at where your processes are running, htop is a great tool for this:<BR>
<a href="http://htop.sourceforge.net/" target="_blank">http://htop.sourceforge.net/</a> <BR>
<BR>
(top can of course show this information - but htop is like top on steroids)<BR>
<br />
<br />
The contents of this e-mail are confidential and for the exclusive use of the intended recipient.
If you are not the intended recipient you should not read, copy, retransmit or disclose its contents.
If you have received this email in error please delete it from your system immediately and notify us either by email or telephone.
The views expressed in this communication may not necessarily be the views held by McLaren Racing Limited.
<br />McLaren Racing Limited | McLaren Technology Centre | Chertsey Road | Woking | Surrey | GU21 4YH | UK | Company Number: 01517478
</BODY></HTML>