Hi, I am new to this list. I have recently started using the open embedded repository to build a distribution for a mini-cluster that I am building at the moment. While there is some documentation about how to use bitbake, I personally found it hard to find documentation on how bitbake worked from the base up, while there are some good discussions on here on the inner workings of bb, in code documentation is pretty minimal.
I have started reading through the code to try and figure out how bb works and what the different componants are. If anyone knows any resources that could help me, please do let me know. I am looking at maybe documenting the code 1.6.x and would like it if it was helpful to everyone; I have used doxygen in the past but would very much like to hear what you would like to use. Regarding the sqlite db backend, I had a query. Were the tests conducted using in-memory db or a filesystem db ? From past experience with real-time applications I found sqlite performance to be especially _very_ slow on writes using db's stored on the filesystem, sqlite finalizes every single operation and has no buffering (it may be different now). However as someone no the list mentioned python dictionaries are probably almost always faster than doing it on a sql back-end. However sql might bring to the table, a stricter structure and the ability to tie together sophisticated queries - to ease tedious operations like joins. I was wondering whether anyone has considered using a cluster to speed up builds ? A very simple approach would be to have the base directory mounted over nfs over all nodes, and then dispatch jobs by running rsh using a scheduling algorithm. I have seen that there is a parallel build option within bb but I haven't played with that option. As I understand bb can run jobs on <n> number of threads and provided that the machine you are running it on has more than one core a speedup can be achieved. I am wondering whether multi-threading is going to be used in bitbake-ng. Because most machines have two cores and to the most four, the approach of multi-threading (shared memory programming) is not very scalable when it comes to clusters. While there are abstractions available that will make a cluster of computers appear as one enabling multithreading to run transparently, it is hard to squeeze power out using smp programming. Rather I would use message-passing systems using standard tcp/ip style ipc, and because of the class of application (long process cycle, short messaging in between) using message passing wouldn't impose very much overhead on purely smp machines. I would very much like to hear any responses. cheers, -ravi =)
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