Re: Slow Performance on a XEON E5504

Hi Scott,

the controller is a HP i410 running 3x300GB SAS 15K / Raid 5

Mit freundlichen Grüßen

Felix Schubert

Von meinem iPhone gesendet :-)

Am 25.08.2012 um 14:42 schrieb Scott Marlowe <scott(dot)marlowe(at)gmail(dot)com>:

> On Sat, Aug 25, 2012 at 6:07 AM, Felix Schubert <input(at)fescon(dot)de> wrote:
>> Hello List,
>>
>> I've got a system on a customers location which has a XEON E5504 @ 2.00GHz Processor (HP Proliant)
>>
>> It's postgres 8.4 on a Debian Squeeze System running with 8GB of ram:
>>
>> The Postgres Performance on this system measured with pgbench is very poor:
>>
>> transaction type: TPC-B (sort of)
>> scaling factor: 1
>> query mode: simple
>> number of clients: 40
>> number of transactions per client: 100
>> number of transactions actually processed: 4000/4000
>> tps = 158.283272 (including connections establishing)
>> tps = 158.788545 (excluding connections establishing)
>
> For a single thread on a 10k RPM drive the maximum number of times per
> second you can write and get a proper fsync back is 166. This is
> quite close to that theoretical max.
>
>> The same database on a Core i7 CPU 920 @ 2.67GHz, 8 cores with 8GB RAM same distro and Postgresql Version is much faster:
>>
>> transaction type: TPC-B (sort of)
>> scaling factor: 1
>> query mode: simple
>> number of clients: 40
>> number of transactions per client: 100
>> number of transactions actually processed: 4000/4000
>> tps = 1040.534002 (including connections establishing)
>> tps = 1065.215134 (excluding connections establishing)
>
> This is much faster than the theoretical limit of a single 10k RPM
> drive obeying fsync.
>
> I'll ignore the rest of your post where you get 53 tps after
> optimization. The important thing you forgot to mention was your
> drive subsystem here. I'm gonna take a wild guess that they are both
> on a single drive and that the older machine is using an older SATA or
> PATA interface HD that is lying about fsync, and the new machine is
> using a 10k RPM drive that is not lying about fsync and you are
> getting a proper ~150 tps from it.
>
> So, what kind of IO subsystems you got in those things?
>
>
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