New Approach for Datacenter Networks and Stacks for Low Latency

In a irc channel this week, one guy posted a link about visualization latency in a data center switching network .

And it was really good video for understanding how congestion happens inside the switch infrastructure and a very original idea to overcome this problem!

I tried to get a bit more info about the video and ended in the page of that paper:

And see if there was any implementation:

I am not a researcher but the idea is quite original and it seems you dont need to re-invent the wheel. In the github repo even there is an example in P4. P4 is going to be big, and Barefoot has already commercial solutions about it with their tofino chip. Let’s see what Intel does with it…

Based on a continuation paper, it seems there is no much traction from the big cloud providers, and it surprises me, these guys have the muscle to make this kind of things. I always heard that hardware is very expensive to built and software is not. So there are few player willing to invest in new ideas. Everytime you hear about unicorn companies, nearly all of them are software companies.

And another paper says it needs more tuning/debugging.

I don’t know if it will successful in the future but I think it was interesting watching the video and reading about the concept.

Lemon Polenta Cake

I had a couple of lemon in the fridge so I wanted to used them in a cake. I had a recipe that I wanted to try for some time so this was my chance.


  • 250g ground almonds
  • 100g fine polenta / cornmeal
  • 50g coarse polenta
  • 1 teaspoon baking powder
  • 250g (good) butter + a bit for greasing
  • zest and juice of 3 (good) lemons (medium size)
  • 4 free range / organic medium eggs


  • Preheat oven at 180C. Grease a 20cm round cake tin
  • Mix the almonds, both kinds of polenta and the baking powder together in a bowl and put aside.
  • Put the butter, lemon zest and sugar into another bowl and cream together. I used a wooden spoon. Get ready to sweat a bit. Once everything is mixed, start adding an egg at each time, mix well, and add another.
  • Add the initial bow with the polenta and almond to the mixture. Mix well until everything is combined. Add the lemon juice. Mix well.
  • Poor everything on the tin and smooth the top. Bake for 50-55 minutes. Check the top is brown.

It is a quick, moist and easy cake. And it is tasty!

First step into OpenBSD

This week Job Snijders advertised the latest version of openbsd. I have been always a dreamer of being a hacker (like the movies) and the best guys when I was in Uni were Linux users. I had no idea what Linux/Unix/BSD was at that time. At the end (by the 4th year in Uni) I managed to install Linux in my windows PC without destroying anything. And fortunately, I have been using it since then. Learning more and still fortunately, in the last 6 years, using it everyday at work too.

Still very very far away from being a hacker though πŸ™‚

In this time, I have read a bit about the BSD vs Linux threads about licenses, security, etc. And actually I was always keen to learn a bit. In Motorola, I had to use Solaris (even managed to get a certification!).

So this week, I tried to setup a VM in my debian laptop for using OpenBSD 6.7

I found and followed this link, so all credits for the author.

First I downloaded openbsd 6.7 (install67.iso) from here. There are many mirrors around the world. Prepare the file:

/var/lib/libvirt/images# ls -ltr
total 1386064
-rwxr--r-- 1 libvirt-qemu libvirt-qemu 996671488 Apr 6 2018 debian-VAGRANTSLASH-stretch64_vagrant_box_image_9.1.0.img
-rwxr--r-- 1 libvirt-qemu libvirt-qemu 950796288 Nov 29 23:17 centos-VAGRANTSLASH-7_vagrant_box_image_1905.1.img
-rw-r--r-- 1 ss ss 470118400 May 21 23:23 install67.iso
root@athens:/var/lib/libvirt/images# chown libvirt-qemu.libvirt-qemu install67.iso
/var/lib/libvirt/images# mv install67.iso openbsd67.iso

Now start the installation:

/var/lib/libvirt/images# virt-install \
--name=openbsd \
--virt-type=kvm \
--memory=2048,maxmemory=4096 \
--vcpus=2,maxvcpus=2 \
--cpu host \
--os-variant=openbsd5.8 \
--cdrom=/var/lib/libvirt/images/openbsd67.iso \
--network=bridge=virbr0,model=virtio \
--graphics=vnc \
--disk path=/var/lib/libvirt/images/openbsd67.qcow2,size=40,bus=virtio,format=qcow2

Starting install…
Allocating 'openbsd67.qcow2' | 40 GB 00:00:01

Something that confused my was that I was installing openbsd6.7 but the os-variant in the command must be obenbsd5.8. Anything else, fails.

In my setup, I have virt-viewer installed so it opened up and finished the installation using that.

I was surprised how quick was everything and didnt find any problem:

Once I logged in, I felt useless πŸ™‚ I used a bit the shell and tested I could ssh from my host pc to the openbsd vm.

So now, I can find a book of openbsd for dummies and get going!

So close virt-viewer and stop the VM:

/var/lib/libvirt/images# virsh
virsh # list
Id Name State
2 openbsd running
virsh #
virsh #
virsh # destroy openbsd
Domain openbsd destroyed
virsh # list
Id Name State
virsh #
virsh # list --all
Id Name State
openbsd shut off
virsh #

Test we can start up again:

# virsh
Welcome to virsh, the virtualisation interactive terminal.
Type: 'help' for help with commands
'quit' to quit
virsh # list --all
Id Name State
openbsd shut off
virsh # start openbsd
Domain openbsd started
virsh # list --all
Id Name State
3 openbsd running
virsh # exit
# virt-viewer

Deep Work

I have just finished “Deep Work” from Cal Newport. For a long time I have believed that multitasking is the best thing to be productive but with the years passing by I realised that like a computer, context switching is very expensive on me. You can’t really concentrate in some demanding thing and then try to be on top of small things and interrupted by everybody. I am happy that I am not use social media but still at work I am easily distracted by people demands, emails, etc.

And I am pretty sure that It is not just me. Most people suffer this. And to be honest, I want to improve, I want to make a more meaningful job with my time. And life (like Winifred Gallagher) Cal’s examples (himself and others) are really good. I liked quite a lot the one regarding Daniel Kilov and how to memorize a deck of cards. I think this is a good exercise to execute deep concentration in small chunks of time, that is actually the most probably outcome in (most people) normal day.

You can do it. But you need to work hard for it. The society, working environment and yourself are not going to make it easy.

I think with the lockdown period, it is a good moment to put these techniques in practice.

I need to pay less attention to the emails and slack. I dont have to be the quickest answering something… (that is so good for your ego….) I need to really prioritize my working hours and tasks to focus on with a time frame. I need to make myself accountable, stop blaming somebody else. And communicate, make my peers that I will focus in things I will not answer immediately (if you are my CTO, maybe not πŸ™‚ And as a manager, make my team members better: make them to take more ownership so they can deal with problems by themselves. And schedule times of the day to check emails and/or attend meetings.

One thing I have done, it is to put a pink sticker close to my screen saying “ONE THING AT EACH TIME”. I did this before reading the book as a reminder from a speech at work of a brilliant guy in his last day. And he said he learned that sentence from our CTO. That got burned in my mind. I have used it mainly from troubleshooting. It has been a critical tool that I have applied successfully many times since then. But I can be applied to more things as “Deep Work”

All very nice words. Let’s make it happen.