Robert Haas <robertmh...@gmail.com> writes: > On Wed, Apr 13, 2016 at 10:42 AM, Tom Lane <t...@sss.pgh.pa.us> wrote: >> No, you're ignoring my point, which is what happens on single-CPU >> 32-bit machines, and whether we aren't going to destroy performance >> on low-end machines in pursuit of better performance on high-end.
> One of us is confused, or we're just talking past each other, because > I don't think I'm ignoring your point at all. In fact, I think I just > responded to it rather directly. I agree that the exact risk you are > describing exists. However, the multiple spinlock cycles that you are > concerned about will only occur on a platform that doesn't support > 64-bit atomics. In order to test whether there is a performance > problem on such hardware, or how serious that problem is, we'd need to > have access to such hardware, and I don't know where to find any such > hardware. Do you? As Andres says, low-end ARM machines are probably the most common such hardware right now. I have two non-ARM machines in the buildfarm that certainly haven't got such instructions (prairiedog and gaur/pademelon). Now I wouldn't propose that we need to concern ourselves very much with performance on those two decade-plus-old platforms, but I do think that performance on small ARM machines is still of interest. regards, tom lane -- Sent via pgsql-hackers mailing list (firstname.lastname@example.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers