On Sep 18, 2014 9:32 PM, Andrew Dunstan <and...@dunslane.net> wrote:
>
>
> On 09/18/2014 03:09 PM, Mkrtchyan, Tigran wrote: 
> > 
> > ----- Original Message ----- 
> >> From: "Josh Berkus" <j...@agliodbs.com> 
> >> To: pgsql-performance@postgresql.org 
> >> Sent: Thursday, September 18, 2014 7:54:24 PM 
> >> Subject: Re: [PERFORM] postgres 9.3 vs. 9.4 
> >> 
> >> On 09/18/2014 08:09 AM, Mkrtchyan, Tigran wrote: 
> >>>>> 9.4beta2: 
> >>>>> ... 
> >>>>> 
> >>>>>>>          0.957854        END; 
> >>>>>>> 
> >>>>> Looks like IO. 
> >>> Postgres internal IO? May be. We get 600MB/s on this SSDs. 
> >> While it's possible that this is a Postgres issue, my first thought is 
> >> that the two SSDs are not actually identical.  The 9.4 one may either 
> >> have a fault, or may be mostly full and heavily fragmented.  Or the Dell 
> >> PCIe card may have an issue. 
> > 
> > We have tested both SSDs and they have identical IO characteristics and 
> > as I already mentioned, both databases are fresh, including filesystem. 
> > 
> >> You are using "scale 1" which is a < 1MB database, and one client and 1 
> >> thread, which is an interesting test I wouldn't necessarily have done 
> >> myself.  I'll throw the same test on one of my machines and see how it 
> >> does. 
> > this scenario corresponds to our use case. We need a high transaction rate 
> > per for a single client. Currently I can get only ~1500 tps. Unfortunately, 
> > posgtress does not tell me where the bottleneck is. Is this is defensively 
> > not the disk IO. 
> > 
> > 
> > 
>
>
> This is when you dig out tools like perf, maybe.

Do you have a better suggestions ?

>
> cheers 
>
> andrew 

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