Re: Two identical systems, radically different performance

From: Craig James <cjames(at)emolecules(dot)com>
To: Claudio Freire <klaussfreire(at)gmail(dot)com>
Cc: Evgeny Shishkin <itparanoia(at)gmail(dot)com>, pgsql-performance(at)postgresql(dot)org
Subject: Re: Two identical systems, radically different performance
Date: 2012-10-08 22:48:52
Message-ID: CAFwQ8rdmzO046cXO-mqcsZKsj9Ch_W-mfiJpeQnOx8xob-SMVw@mail.gmail.com
Views: Raw Message | Whole Thread | Download mbox | Resend email
Thread:
Lists: pgsql-performance

On Mon, Oct 8, 2012 at 3:44 PM, Claudio Freire <klaussfreire(at)gmail(dot)com>wrote:

> On Mon, Oct 8, 2012 at 7:25 PM, Craig James <cjames(at)emolecules(dot)com> wrote:
> >> > But why? What have I overlooked?
> >>
> >> Do you have readahead properly set up on the new one?
> >
> >
> > # blockdev --getra /dev/sdb1
> > 256
>
>
> It's probably this. 256 is way too low to saturate your I/O system.
> Pump it up. I've found 8192 works nice for a system I have, 32000 I
> guess could work too.
>

But again ... the two systems are identical. This can't explain it.

Thanks,
Craig

In response to

Responses

Browse pgsql-performance by date

  From Date Subject
Next Message Claudio Freire 2012-10-08 22:50:30 Re: Two identical systems, radically different performance
Previous Message Evgeny Shishkin 2012-10-08 22:46:38 Re: Two identical systems, radically different performance