[Bugs] [Bug 1258905] New: Sharding - read/write performance improvements for VM workload

[bugzilla at redhat.com]

https://bugzilla.redhat.com/show_bug.cgi?id=1258905

            Bug ID: 1258905
           Summary: Sharding - read/write performance improvements for VM
                    workload
           Product: GlusterFS
           Version: mainline
         Component: sharding
          Assignee: bugs at gluster.org
          Reporter: kdhananj at redhat.com
        QA Contact: bugs at gluster.org
                CC: bugs at gluster.org



Description of problem:

Paul Cuzner in his testing of sharding in hyperconvergence environment noted a
3x write latency and 2x read latency.
One network operation that can be eliminated among the many things that shard
translator does in every WRITEV and READV fop is the LOOKUP that is done on the
zeroth shard to fetch the size and block_count xattr. Since VM workload is a
single-writer use-case, and the client that wrote to a file is always the one
that is going to read it, the size and block count xattr could be cached (and
kept up-to-date) in the inode ctx of the main file, thereby saving the need for
the (extra) LOOKUP every time.

The other place where network fops can be avoided is XATTROP, if/when there is
a WRITEV that does not change the file size && block count,

Version-Release number of selected component (if applicable):


How reproducible:


Steps to Reproduce:
1.
2.
3.

Actual results:


Expected results:


Additional info:

-- 
You are receiving this mail because:
You are the QA Contact for the bug.
You are on the CC list for the bug.
You are the assignee for the bug.