On 2014-02-05 09:57:11 -0500, Tom Lane wrote: > Andres Freund <and...@2ndquadrant.com> writes: > > On 2014-02-04 16:24:02 -0800, Peter Geoghegan wrote: > >> I suspect that the scenario described in this article accounts for the > >> quite noticeable effect reported: http://danluu.com/3c-conflict > > > I don't think that's applicable here. > > Maybe, or maybe not, but I think it does say that we should be very wary > of proposals to force data structure alignment without any testing of the > consequences.
I agree it needs testing, but what the page is talking about really, really doesn't have *anything* to do with this. What the author is talking about is not storing things *page* aligned (I.e. 4k or a multiple). The problem is that the beginning of each such page falls into the same cacheline set and thus doesn't utilize the entire L1/L2/L3 but only the single set they map into. Greetings, Andres Freund -- Andres Freund http://www.2ndQuadrant.com/ PostgreSQL Development, 24x7 Support, Training & Services -- Sent via pgsql-hackers mailing list (firstname.lastname@example.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers