Andres Freund <andres@anarazel.de> writes:
> wal-writer-flush-after doesn't really fit into this section, it wasn't
> affected by any of the above commits, and the change in 9.6 is to make
> it *less* aggressive in flushing (as you listed in a separate entry).
I hadn't focused on this before, but wal_writer_flush_after is new in 9.6.
I think the right thing to do here is to remove the separate entry for
7975c5e0a and just treat it as part of this group.
> Hm. Kernel traffic is maybe a bit hard to understand (guess you're
> referring to the number of syscalls)? Isn't that also affecting actual
> IO? But mostly it's about our own locking around relation extension?
Right, I was thinking about syscalls. But given that this only happens
under contention, maybe best to just take that part out.
> An important benefit here is that after that patch we can increase
> the padding of the locks remaining lwlocks; which we previously
> avoided out of memory usage concerns.
I doubt it's necessary to explain that in the release notes...
> Hm, I guess we need a warning about reindexing such indexes after a pg_upgrade somwhere?
See discussion with Noah yesterday.
regards, tom lane