On Wed, Aug 30, 2017 at 4:46 PM, Christoph Hellwig [off-list ref] wrote:

Oops.

Yes, except for the case of calling xlog_state_release_iclog
ourselves we can't claim that the cache has been flushed.  In
fact I'm not even sure that is save, if ic_refcnt makes
xlog_state_release_iclog exit early, so we might have to
pass additional information around there.

With this change, for the multiple fsyncing tasks workload, the majority won't
be optimized, so the remaining code is only really optimizing the single
process doing seldom fsync case.

I wonder if it's worth keeping the optimization around at all?