| From: | Shaun Thomas <sthomas(at)optionshouse(dot)com> |
|---|---|
| To: | Mark Kirkwood <mark(dot)kirkwood(at)catalyst(dot)net(dot)nz>, Josh Berkus <josh(at)agliodbs(dot)com>, <pgsql-performance(at)postgresql(dot)org> |
| Cc: | "Graeme B(dot) Bell" <grb(at)skogoglandskap(dot)no> |
| Subject: | Re: Turn off Hyperthreading! WAS: 60 core performance with 9.3 |
| Date: | 2014-08-21 14:14:56 |
| Message-ID: | 53F5FEE0.8040505@optionshouse.com |
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| Thread: | |
| Lists: | pgsql-performance |
On 08/20/2014 06:14 PM, Mark Kirkwood wrote:
> Notwithstanding the above results, my workmate Matt made an interesting
> observation: the scaling graph for (our) 60 core box (HT off), looks
> just like the one for our 32 core box with HT *on*.
Hmm. I know this sounds stupid and unlikely, but has anyone actually
tested PostgreSQL on a system with more than 64 legitimate cores? The
work Robert Haas did to fix the CPU locking way back when showed
significant improvements up to 64, but so far as I know, nobody really
tested beyond that.
I seem to remember similar choking effects when pre-9.2 systems
encountered high CPU counts. I somehow doubt Intel would allow their HT
architecture to regress so badly from Nehalem, which is almost
3-generations old at this point. This smells like something in the
software stack, up to and including the Linux kernel.
--
Shaun Thomas
OptionsHouse, LLC | 141 W. Jackson Blvd. | Suite 800 | Chicago IL, 60604
312-676-8870
sthomas(at)optionshouse(dot)com
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