[LU-2771] Wasted space in ldlm_lock structure

• Type: Improvement
• Resolution: Fixed
• Priority: Minor
• Fix Version/s: Lustre 2.5.0, Lustre 2.16.0
• Labels: locking patch
• Assignee: Keith Mannthey (Inactive)
• Reporter: Bruce Korb (Inactive)

Description

There is an 8 byte write only field and some separated flag bits that trigger another 8 bytes of extra alignment padding that are not necessary. There are also a couple of fields that are only used on the server side and others only used on the client side. These fields could be overlaid, with 24 bytes easily saved. This is important on systems where 100's of thousands of these structures get allocated.

My first comment will show one approach for coalescing all the flag bits into a single 64 bit flag word.

Comments

[Bruce Korb (Inactive)]

That's right - I remember: error: excess elements in struct initializer

There was more to it than just removing an assignment. There were the initializers, too.
Tomorrow.

[Bruce Korb (Inactive)]

http://review.whamcloud.com/#change,5312 – Patch Set 11: No score
trying a new review

[Bruce Korb (Inactive)]

OK, coming. That generated header was sufficiently preliminary that I was not sure it would compile even. Actually, I'd guess it would not. But the approach is visible. Another 30-60 minutes, and I should have something that compiles.

And I've removed the osc_ldlm_weigh_ast() -> ei_cb_wg -> lcs_weigh -> dead store in l_weigh_ast chain.

[Andreas Dilger]

Bruce, it is easier to review changes in the form of a patch. If you are just looking for comments and not landing, please add in the commit comment:

Test-Parameters: fortestonly testlist=runtests

so that it will run only the one test. We don't have a "don't test anything" marker yet.

[Bruce Korb (Inactive)]

Xyratex bug id MRP-376

[Bruce Korb (Inactive)]

an approximation of the new bit field code