Subject: Re: How to get higher tps
From: Mark Lewis <mark.lewis@mir3.com>
To: Marty Jia <mjia@ask.com>
Cc: pgsql-performance@postgresql.org
In-Reply-To: 
 <0B9A8C89DCC3AB488A78A4DE0FECDA90019E30D4@SITE3MAIL04.jeeves.ask.info>
References: 
 <0B9A8C89DCC3AB488A78A4DE0FECDA90019E30D4@SITE3MAIL04.jeeves.ask.info>
Content-Type: text/plain
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Organization: MIR3, Inc.
Date: Mon, 21 Aug 2006 14:47:25 -0700
Message-Id: <1156196845.9657.82.camel@archimedes>
Mime-Version: 1.0

Not much we can do unless you give us more info about how you're testing
(pgbench setup), and what you've done with the parameters you listed
below.  It would also be useful if you told us more about your drive
array than just "3Par".  We need to know the RAID level, number/speed of
disks, whether it's got a battery-backed write cache that's turned on,
things like this.

Like Jeff just said, it's likely that you're waiting for rotational
latency, which would limit your maximum tps for sequential jobs based on
the number of disks in your array.  For example, a 2-disk array of 10k
RPM disks is going to max out somewhere around 333 tps.  (2*10000/60).

-- Mark Lewis

 

On Mon, 2006-08-21 at 16:45 -0400, Marty Jia wrote:
> I'm exhausted to try all performance tuning ideas, like following
> parameters
> 
> shared_buffers 
> fsync 
> max_fsm_pages
> max_connections 
> shared_buffers  
> work_mem 
> max_fsm_pages
> effective_cache_size 
> random_page_cost 
> 
> I believe all above have right size and values, but I just can not get
> higher tps more than 300 testd by pgbench
> 
> Here is our hardware
> 
> 
> Dual Intel Xeon 2.8GHz
> 6GB RAM
> Linux 2.4 kernel
> RedHat Enterprise Linux AS 3
> 200GB for PGDATA on 3Par, ext3
> 50GB for WAL on 3Par, ext3
> 
> With PostgreSql 8.1.4
> 
> We don't have i/o bottle neck. 
> 
> Whatelse I can try to better tps? Someone told me I can should get tps
> over 1500, it is hard to believe.
> 
> Thanks
> 
> Marty
> 
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