Re: openldap.git branch mdb.master updated. 3630066843b7ca6b2cd12911d3e2fe3314cd4549

[Hallvard Breien Furuseth <h.b.furuseth@usit.uio.no>]

On 27/07/14 03:27, openldap-commit2devel@OpenLDAP.org wrote:
> commit 3630066843b7ca6b2cd12911d3e2fe3314cd4549
> Author: Howard Chu <hyc@symas.com>
> Date:   Sat Jul 26 18:16:02 2014 -0700
>
>      Fix MIPS cache coherency on Linux
>
>      MIPS chips require manual control of on-chip caches. The cacheflush
>      syscall being used here only exists on MIPS Linux, other OSs will
>      require revisiting.

I may be guessing wrong what's going on here, but anyway:

CACHEFLUSH looks like it belongs before setting me_txns->mti_txnid
which tells other threads/processes to use the new metapage.

If so, MDB_NOLOCK may be in trouble since it uses pick_meta()
instead of mti_txnid.  Should there be a separate CACHEFLUSH after
writing the datapages if MDB_NOLOCK, and the current CACHEFLUSH
should just flush the metapages?

Does the code contradict this comment above, or is it about
something else?
/* Memory ordering issues are irrelevant ... */

--
Hallvard