Re: simplify register_dirty_segment()

"Tom Lane" <tgl@sss.pgh.pa.us> writes
> It would be a reasonable
> bet for a kernel designer to assume that fsync() is generally going to
> have to wait for some I/O and so a bit of CPU overhead isn't really
> going to matter.

Reasonable.

>
> Adjusting such a global refcount would require global locks, which is
> just what you were hoping to avoid :-(

I don't want to avoid the global locks but to alleviate it :-( Think the
frequency of open()/close() will be much less than write(). Also the shmem
space required. On further thought, I agree that this is unneccessary if for
BgWriterCommLock reason - because currently BufMgrLock doesn't bother us too
much, which is more intensively used, this lock is just nothing.

Regards,
Qingqing