[LU-1158] nanosecond timestamp support for Lustre

• Type: Improvement
• Resolution: Unresolved
• Priority: Major
• Affects Version/s: Lustre 2.4.0
• Story Points: 3
• Assignee: Feng Lei
• Reporter: Andreas Dilger

Description

The current Lustre network protocol has support for a 64-bit timestamp of seconds, but does not have a field for passing the nanosecond timestamp from clients to servers and back again.

It would be relatively straight-forward to put 3x __u32 nanosecond timestamps in the reserved fields in struct obdo and struct mdt_body. These fields are currently always initialized to 0, so there wouldn't even need to be a protocol change or feature to begin using these fields for nanoseconds - just copy them in/out of the RPC structures, and old clients/servers will just store 0 there, and ignore any nanosecond timestamps that are sent to them (no differently than they do today).

It is more complex to add the nanosecond timestamps to struct ost_lvb, which is most commonly used for glimpse locks (stat) on OST objects. This will require a structure change to fit the extra 3x __u32 nanosecond timestamps into ost_lvb, which may require a protocol change. It may be possible if this structure is passed in a separate ptlrpc message buffer that the larger size will be ignored by older clients, which would avoid the need for additional complexity for interoperability.

Issue Links

• is related to: LU-12922 pjdfstest chown_00: POSIX compliance failed on lustre
• is related to: LU-4050 NFS reexport issue
• is related to: LU-10934 integrate statx() API with Lustre
• is related to: LU-11971 Send file creation time to clients
• is related to: LUDOC-92 Nanosecond Time Stamps Doc Changes
• is related to: LU-9019 Migrate lustre to standard 64 bit time kernel API
• Trackbacks: Summer Intern: Plusses and deltas board Isami joined Whamcloud and leaves tomorrow after working the summer on site at TACC. He completed the nanosecond time stamp
• Trackbacks: Summer Intern, Plusses and deltas board Isami joined Whamcloud and leaves tomorrow after working the summer on site at TACC. He completed the nanosecond time stamp
• Trackbacks: Changelog 2.1 Changes from version 2.1.2 to version 2.1.3 Server support for kernels: 2.6.18308.13.1.el5 (RHEL5) 2.6.32279.2.1.el6 (RHEL6) Client support for unpatched kernels: 2.6.18308.13.1.el5 (RHEL5) 2.6.32279.2.1....
• Trackbacks: Project Ideas Information for Developers Working on Lustre will quickly introduce a developer to the always interesting and impressive world of HPC, where the systems are the largest in the world,...