deepakarumugam.s@nutanix.com has uploaded this change for review. ( https://review.gerrithub.io/c/ffilz/nfs-ganesha/+/1198218?usp=email ) Change subject: Limit the number of files we delegate ...................................................................... Limit the number of files we delegate Today each delegation state places a refcnt on a mdcache entry.Ganesha can therefore only release this mdcache entry - when this delegation state is destroyed. A delegation state can only be destroyed when, (1) Client id expires (2) Some other client tries to do write style operations on the file (3) Client voluntarily returns the delegation So if you have a scenario where active clients are mostly reading a bunch of files from the server - today we have to wait on the client to voluntarily return the delegation before we can release the corresponding mdcache entry. Typically linux clients (this was tested using some flavor of centos7) return delegations on unused files within seconds to minutes. But what was seen was that even if the application on the client side is continuosly stating a file we donot return the delegation. When this is done at scale we end up with OOMs on the server because the mdcache entries corresponding to the delegated files cannot be released. One could argue that we should instead do a delegation recall as part of the mdcache reaper or some other reaper - which can be helpful but that still puts the server in the good grace of the clients. Therefore would like to introduce a limit on the number of files we delegate - which can be helpful in tuning the server memory usage in scenarios like above. Tested this change with pynfs based tests that get delegations on a bunch of files and never return it Change-Id: I092e47cec176dcbb191c28b98e8fa897304ba173 Signed-off-by: Deepak Arumugam Sankara Subramanian <deepakarumugam.s@nutanix.com> --- M src/SAL/state_deleg.c M src/include/gsh_config.h M src/support/nfs_read_conf.c 3 files changed, 23 insertions(+), 0 deletions(-) git pull ssh://review.gerrithub.io:29418/ffilz/nfs-ganesha refs/changes/18/1198218/1 -- To view, visit https://review.gerrithub.io/c/ffilz/nfs-ganesha/+/1198218?usp=email To unsubscribe, or for help writing mail filters, visit https://review.gerrithub.io/settings?usp=email Gerrit-MessageType: newchange Gerrit-Project: ffilz/nfs-ganesha Gerrit-Branch: next Gerrit-Change-Id: I092e47cec176dcbb191c28b98e8fa897304ba173 Gerrit-Change-Number: 1198218 Gerrit-PatchSet: 1 Gerrit-Owner: deepakarumugam.s@nutanix.com