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Showing posts from July, 2015

[Python] Effective Python

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Two weeks ago, my friend discussed the best practice for Django and Python in programming.
After that for a while, one day I just came up with a idea: I read a book "Effective C++" and why not there is a book about "Effective Python"? So, here it is: http://www.effectivepython.com/
I wish I can find some time to walk through this book.

[Neutron] Slow network speed between VM and external

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Recently I encountered a situation of the VM's network performance that is pretty low. For instance, if upload a image to Glance via my VM to run glance cli command, the actual transmit speed is around the following data:
RX: 130 Kbps TX: 150 Kbps
My OpenStack's network service is with GRE segmentation on Neutron. Why? After google the web, I found some people had the same issues as I had: https://ask.openstack.org/en/question/25306/slow-network-speed-between-vm-and-external/
They talked about the approach on the VM to solve the issue and this works
> ethtool -K eth0 gro off > ethtool -K eth0 tso off
But, for my case I think it is not solve from the root cause so that I take time to do the research for TCP segmentation offload and GRE. Finally I find the root cause:
MTU need to adjust when using GRE network service.
http://docs.openstack.org/juno/install-guide/install/yum/content/neutron-network-node.html
Quote:
"Tunneling protocols such as GRE include additional packet he…