On Sun, Feb 2, 2014 at 6:00 AM, Andres Freund <and...@2ndquadrant.com> wrote: > The changed algorithm for lwlock imo is an *algorithmic* improvement, > not one for a particular architecture. The advantage being that locking > a lwlock which is primarily taken in shared mode will never need need to > wait or loop.
I agree. My point was only that the messaging ought to be that this is something that those with multi-socket Intel systems should take note of. > Yes, that branch is used by some of them. But to make that clear to all > that are still reading, I have *first* presented the patch & findings to > -hackers and *then* backported it, and I have referenced the existance > of the patch for 9.2 on list before. This isn't some kind of "secret > sauce" deal... No, of course not. I certainly didn't mean to imply that. My point was only that anyone that is affected to the same degree as the party with the 4 socket server might be left with a very poor impression of Postgres if we failed to fix the problem. It clearly rises to the level of a bugfix. > That might be something to do later, as it *really* can hurt in > practice. We had one server go from load 240 to 11... Well, we have to commit something on master first. But it should be a priority to avoid having this hurt users further, since the problems are highly predictable for certain types of servers. > But I think we should first focus on getting the patch ready for > master, then we can see where it's going. At the very least I'd like to > split of the part modifying the current spinlocks to use the atomics, > that seems far to invasive. Agreed. > I unfortunately can't tell you that much more, not because it's private, > but because it mostly was diagnosed by remote hand debugging, limiting > insights considerably. Of course. -- Peter Geoghegan -- Sent via pgsql-hackers mailing list (firstname.lastname@example.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers