I am looking at possibilities to implement QoS (quality of service) in an NFS server -- for a multiuser HPC environment, on NFSv3. The desire is for a fully loaded server to process requests in some kind of "fair share" (like round robin) or priorities based on some attribute; eg. uid at the client, request type + origin, or even directory etc. Criteria could be fairly blunt and specific to our use case to begin with. I've looked at the code with the following ideas for where to start. It seems the implementation depends a lot on which attributes to share/schedule on: 1) by client IP: make use the existing structures enhance the svc_xprt_enqueue/dequeue process to schedule svc_xprt as these are already per-client 2) by client uid or other RPC attribute: have svc_recv make multiple calls to svc_handle_xprt buffer the requests into multiple queues held at svc_pool (re-use xpt_deferred?) 3) by NFS operation, file handle etc.: most awkward, as there is not buffering of requests at the NFS level or shared between threads perhaps do as (2) but with a function in svc_program to return scheduling criteria It looks like I need to consider the behaviour when there are multiple svc_pool (ie. NUMA) This is the first time I've looked into this code, I'm interested in any comments/criticisms or alternatives. Thanks -- Mark -- To unsubscribe from this list: send the line "unsubscribe linux-nfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
