Hi Vivek, Me, Divyesh, Fernando and Yoshikawa had a chance to have a chat with Jens about IO controller during Linux Plumbers Conference '09. Jens expressed his concerns about the size and complexity of the patches. I believe that is a reasonable concern. We talked about things that could be done to reduce the size of the patches. The requirement that the "solution has to work with all IO schedulers" seems like a secondary concern at this point; and it came out as one thing that can help to reduce the size of the patch set. Another possibility is to use a simpler scheduling algorithm e.g. weighted round robin, instead of BFQ scheduler. BFQ indeed has great properties, but we cannot deny the fact that it is complex to understand, and might be cumbersome to maintain. Also, hierarchical scheduling is something that could be unnecessary in the first set of patches, even though cgroups are hierarchical in nature. We are starting from a point where there is no cgroup based IO scheduling in the kernel. And it is probably not reasonable to satisfy all IO scheduling related requirements in one patch set. We can start with something simple, and build on top of that. So a very simple patch set that enables cgroup based proportional scheduling for CFQ seems like the way to go at this point. It would be great if we discuss our plans on the mailing list, so we can get early feedback from everyone. -- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel
