I learned about a feature of linux called CPU core pinning, which lets you set which cores of a multicore processor your processes are running.

I had a look at what options I had available that I could pay for with the $6 extra credit an extra core for my witness VPS server. I was in the middle of adding a full bitcoin witness node for a trustworthy bitcoin RPC endpoint for my web application.

But I don't want them stepping on each other's access to the CPU, so I started searching for info about how to set which or which number of cores you can set a process to be limited to.

So now, I have my /etc/rc.local containing the following to start up these processes limited to cores, bitcoin has core 0, and the witness 1-3:

sudo mount -o remount,size=32G /dev/shm
sudo -u loki "taskset -c 1-3 steemd -d /work/loki/witness_node_data_dir --shared-file-dir /dev/shm --replay 2>>/dev/null 2>>/home/loki/steemd.l$
sudo -u bitcoin  taskset -c 0  /usr/local/bin/bitcoind -datadir=/home/bitcoin/.bitcoin

You can also set the cores available to running processes like this:

taskset -c -p {cores} {process ID}

for example:

taskset -c -p 0-1 1337

or

taskset -c -p 1-3 80085

So since I have a huge hard drive on this VPS, it holds a full bitcoin blockchain, which runs a witness only on core 0, and the witness has core 1-3.

In the process list above you can see core zero is fully loaded, and using about 24% of total processing capacity, and the other three are running the witness. In theory, if either one locks up a core, it won't stop the other (s) from operating other processes, like ssh, to log in and restart this pesty process.

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We can't code here! This is Whale country!

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