Re: Re: We have got a serious problem with pg_clog/WAL synchronization

Kenneth Marshall <ktm@is.rice.edu> writes:
> Would it be possible to use a latch + version number in
> this case to minimize this problem by allowing all but the checkpoint to
> perform a read-only action on the latch?

How would a read-only action work to block out the checkpoint?

More generally, though, this lock is hardly the one I'd be most
concerned about in an SMP situation.  It's only taken once per
transaction, while there are others that may be taken many times.
(At least two of these, the WALInsertLock and the lock on shared
pg_clog, will need to be taken again in the process of recording
transaction commit.)

What I'd most like to find is a way to reduce contention for the
BufMgrLock --- there are at least some behavioral patterns in which
that is demonstrably a dominant cost.  See past discussions in the
archives ("context swap storm" should find you some recent threads).
        regards, tom lane