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  1. Lustre
  2. LU-11618

implement ladvise rpc_size for optimized performance


    • Type: New Feature
    • Status: Open
    • Priority: Minor
    • Resolution: Unresolved
    • Affects Version/s: None
    • Fix Version/s: None
    • Labels:
    • Rank (Obsolete):


      Originally, the maximum RPC size for bulk I/O can be controlled by
      per-OSC parameter max_pages_per_rpc. Whenever it is possible, the
      OSC will do bulk I/O as large as max_pages_per_rpc for better
      performance. Thus, changing the value of max_pages_per_rpc usually
      affects the I/O performance a lot. However, due to the I/O pattern
      difference, not all applications can get the best performance with
      the same value of max_pages_per_rpc.

      We want to add a new type of ladvise to enabling applications to
      set different RPC sizes for different files. max_pages_per_rpc is
      still the upper limit of the RPC size in all cases. And new
      parameter default_pages_per_rpc has been added and its value is
      the default RPC size. If a ladvise of rpc_size is given to a file,
      the RPC size of the file will be changed according to the ladvise.
      But the maximum RPC size will still limited by max_pages_per_rpc.

      The RPC size of a file configured by ladivse is neither a global
      attribute nor a persistent attribute. Each client may have
      different RPC size for the same file. And the RPC size of the file
      will change back to default_pages_per_rpc when the hint kept in
      memory is lost due to memory shrinkage.


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              • Assignee:
                lixi_wc Li Xi
                lixi_wc Li Xi
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                • Created: