Re: postgres 9.3 vs. 9.4

Hi Tigran,

my debugging tips:

>Some technical details:
>Host: rhel 6.5 2.6.32-431.23.3.el6.x86_64
>256 GB RAM, 40 cores, Intel(R) Xeon(R) CPU E5-2660 v2 @ 2.20GHz
>2x160GB PCIe SSD DELL_P320h-MTFDGAL175SAH

As I know PCIe SSD DELL_P320h = Micron P320h
(
http://www.micron.com/products/solid-state-storage/enterprise-pcie-ssd/p320h-25-inch-pcie-ssd
)

so my suggestions:

#1. Check/Upgrade to the latest Micron kernel driver
**
https://www.google.com/search?q=p420m_p320h_hhhl_installation_guide%2520_.pdf
*** "RHEL version 6.1–6.5: kmod-mtip32xx-<version>.el6.x86_64_rhel6ux.rpm"

#2. And check "Technical Note P320h/P420m SSD Performance Optimization and
Testing"
**
https://www.google.com/search?q=tnfd15_micron_pciessd_performance_testing.pdf

strange :
**** "Table 1: PCIe SSD Hardware and Software Requirements "
***** "Processors with clock speeds greater than 3 GHz (recommended for
best performance)" * ( you have now: 2.20GHz )*
***** "*Up to 8 CPU cores *(logical + physical) with hyperthreading
(recommended)"* ( you have 20! )*

so check performance with* "Turning off Hyper-Threading" *

Imre

2014-09-24 15:03 GMT+02:00 Mkrtchyan, Tigran <tigran(dot)mkrtchyan(at)desy(dot)de>:

>
> With pg_test_timing I can see, that overhead is 48 nsec on my server and
> 32 nsec on the laptop.
> what makes this difference and have it any influence on the overall
> performance?
>
> Tigran.
>
> ----- Original Message -----
> > From: "Mark Kirkwood" <mark(dot)kirkwood(at)catalyst(dot)net(dot)nz>
> > To: "Tigran Mkrtchyan" <tigran(dot)mkrtchyan(at)desy(dot)de>, "Merlin Moncure" <
> mmoncure(at)gmail(dot)com>
> > Cc: "postgres performance list" <pgsql-performance(at)postgresql(dot)org>
> > Sent: Wednesday, September 24, 2014 12:04:12 PM
> > Subject: Re: [PERFORM] postgres 9.3 vs. 9.4
> >
> > On 24/09/14 21:23, Mkrtchyan, Tigran wrote:
> > > Hi Merlin et al.
> > >
> > > after building postgres 9.4 myself from sources I get the same
> performance
> > > as
> > > with 9.3. The difference was in the value of debug_assertions setting.
> > >
> > > Now the next step. Why my 3 years old laptop gets x1.8 times more tps
> than
> > > my one month old server?
> > > And Mark Kirkwood's desktop gets x2 times more tps as well? Is there
> some
> > > special optimization
> > > for i7 which does not work with Intel(R) Xeon(R) CPU E5-2660?
> > >
> > >
> >
> > Yes - firstly, nicely done re finding the assertions (my 9.4 beta2 was
> > built from src - never thought to mention sorry)!
> >
> > I'd guess that you are seeing some bios setting re the p320 SSD - it
> > *should* be seriously fast...but does not seem to be. You could try
> > running some pure IO benchmarks to confirm this (e.g fio). Also see if
> > the manual for however it is attached to the system allows for some
> > optimized-for-ssd settings that tend to work better (altho these usually
> > imply the drive is plugged into an adapter card of some kind - mind you
> > your p320 *does* used a custom connector that does 2.5" SATA to PCIe
> > style interconnect so I'd look to debug that first).
> >
> > Cheers
> >
> > Mark
> >
> >
>
>
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