Make the feature metadata-caching/small file performance production ready

[poornimag]

No description provided.

[ShyamsundarR]

What does this involve? Changing the default options? If so can the option list be elaborated, and more details for this feature be added?

Further, we can drop 3.11 from the issue subject, as that ties a feature to a release, we can track and update that using the milestones instead.

[poornimag]

All these releases it was marked as experimental feature. Making it production feature meaning adding in the release notes that this feature can be used in production setup. The defaults are not changed. Here is the release notes content:
In order to improve the performance of directory operations of Gluster volumes, the maximum metadata (stat, xattr) caching time on the client side is increased to 10 minutes, without compromising on the consistency of the cache. Significant performance improvements can be achieved in the following workloads on FUSE and SMB access, by enabling metadata caching:
Listing of directories (recursive)
Creating files
Deleting files
Renaming files
To enable metadata caching execute the following commands:
# gluster volume set group metadata-cache
# gluster volume set network.inode-lru-limit
n, is set to 50000. It should be increased if the number of concurrently accessed files in the volume is very high. Increasing this number increases the memory footprint of the brick processes.

[gluster-ant]

A patch https://review.gluster.org/17390 has been posted that references this issue.
Commit message: doc: Updated release notes for several features/changes in 3.11.0