2017-05-24 15:02 GMT+02:00 stevenchang1213 <stevenchang1...@gmail.com>:
> hello, > at most 40% total memory, official doc also says so. > you can testify it using pg_prewarm and pgfincore . > There are strong dependency on use case. 40% total memory is related to low memory servers .. 64GB max. High SB requires tuning other options - like writer force Regards Pavel > btw, numa supported? if so, extra care is necessary when starting db > cluster. > > > > 從我的 Samsung Galaxy 智慧型手機傳送。 > > -------- 原始訊息 -------- > 自： Bill Moran <wmo...@potentialtech.com> > 日期： 2017/5/24 20:24 (GMT+08:00) > 至： pgsql-general@postgresql.org > 主旨： [GENERAL] Current best practice for maximum shared_buffers settings on > big hardware? > > > A few years ago, I was working with "big" servers. At least, they were > big for that age, with *128G* of RAM!!!1 Holy mackeral, right?!!? > > Anyway, at that time, I tried allocating 64G to shared buffers and we > had a bunch of problems with inconsistent performance, including "stall" > periods where the database would stop responding for 2 or 3 seconds. > After trying all sorts of tuning options that didn't help, the problem > finally went away after reducing shared_buffers to 32G. I speculated, at > the time, that the shared buffer code hit performance issues managing > that much memory, but I never had the opportunity to really follow up > on it. > > Now, this was back in 2012 or thereabouts. Seems like another lifetime. > Probably PostgreSQL 9.2 at that time. > > Nowadays, 128G is a "medium sized" server. I just got access to one > with 775G. It would appear that I could order from Dell with 1.5T of > RAM if I'm willing to sell my house ... > > Yet, all the docs and advice I'm able to find online seem to have been > written pre 2008 and say things like "if your server has more than 1G > of RAM ..." > > I feel like it's time for a documentation update ;) But I, personally > don't have the experience recently enough to know what sort of > recommendations to make. > > What are people's experience with modern versions of Postgres on hardware > this size? Do any of the experts have specific recommendations on large > shared_buffers settings? Any developers care to comment on any work > that's been done since 2012 to make large values work better? > > -- > Bill Moran <wmo...@potentialtech.com> > > > -- > Sent via pgsql-general mailing list (pgsql-general@postgresql.org) > To make changes to your subscription: > http://www.postgresql.org/mailpref/pgsql-general >
