diff --git a/website/content/en/status/report-2023-10-2023-12/packrat.adoc b/website/content/en/status/report-2023-10-2023-12/packrat.adoc new file mode 100644 index 0000000000..afff0ddb3b --- /dev/null +++ b/website/content/en/status/report-2023-10-2023-12/packrat.adoc @@ -0,0 +1,63 @@ +=== Packrat - NFS client caching on non-volatile storage + +Contact: Rick Macklem + +NFSv4.1/4.2 provides support for a feature called delegations. +When a NFSv4.1/4.2 client holds a delegation, the client has certain rights to a file, including a guarantee that no other client will make changes to the file unless the delegation is recalled. +As such, when a client holds a delegation for a file, it can aggressively cache the file's data, knowing that it will not be modified by other clients until it returns the delegation. + +This project is intended to allow the NFSv4.1/4.2 client to aggressively cache file data on client local non-volatile storage, when the client holds a delegation for the file. +I created a patch long ago to try and do this for NFSv4.0, but it was never at a stage where it was worth using. +This project is a complete rewrite of the patch, done in part because NFSv4.1/4.2 plus other recent NFSv4-related changes make doing this more feasible. + +I now have code running fairly well and hope to have a patch ready for others to test this winter. +Early testing shows promise. +For a test run of "make buildkernel", the test with and without packrat enabled performed as follows: + +.NFS operation counts +[cols="1,1,1,1,1,1", frame="none", options="header"] +|=== +| NFS operation counts +| Getattr +| Lookup +| Read +| Write +| Total RPCs + +|with packrats +|433506 +|99254 +|0 +|0 +|371736 + +|without packrats +|2359913 +|97954 +|10748 +|0 +|2318810 + +|=== + +.Elapsed Run Time +[cols="1,1,1", frame="none", options="header"] +|=== +| Elapsed Run Time (sec) +| with packrat +| without packrat + +| +|5561 +|6203 + +|=== + +As you can see, the packrat case ran a little faster and with fewer RPCs. +Although this test was run on my little LAN, it is hoped that a NFSv4.1/4.2 mount over a WAN would show a larger difference in performance. +I will note that the packrat cache was primed by unrolling a tarball of FreeBSD's [.filename]#/usr/src# into the NFSv4.1/4.2 mount. + +This will be very much an experimental feature, but it is hoped it will allow NFS mounts to be used more effectively, particularily in WAN situations, such as a mobile laptop. + +There is still work to be done, particularily with respect to recovery of delegations after a NFSv4.1/4.2 client restart. +Hopefully, the next status report will include a URL that allows downloading of a patch for user testing.