From: | David Fetter <david(at)fetter(dot)org> |
---|---|
To: | Andrew Dunstan <andrew(at)dunslane(dot)net> |
Cc: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Robert Haas <robertmhaas(at)gmail(dot)com>, Jeff Janes <jeff(dot)janes(at)gmail(dot)com>, pgsql-hackers <pgsql-hackers(at)postgresql(dot)org>, Daniel Farina <daniel(at)heroku(dot)com>, Craig Ringer <ringerc(at)ringerc(dot)id(dot)au>, "Harold A(dot) Giménez" <harold(dot)gimenez(at)gmail(dot)com> |
Subject: | Re: Checkpointer split has broken things dramatically (was Re: DELETE vs TRUNCATE explanation) |
Date: | 2012-07-23 12:41:23 |
Message-ID: | 20120723124123.GA20499@fetter.org |
Views: | Raw Message | Whole Thread | Download mbox | Resend email |
Thread: | |
Lists: | pgsql-hackers pgsql-performance |
On Mon, Jul 23, 2012 at 08:29:16AM -0400, Andrew Dunstan wrote:
>
> On 07/23/2012 12:37 AM, David Fetter wrote:
> >On Tue, Jul 17, 2012 at 06:56:50PM -0400, Tom Lane wrote:
> >>Robert Haas <robertmhaas(at)gmail(dot)com> writes:
> >>>On Mon, Jul 16, 2012 at 3:18 PM, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
> >>>>BTW, while we are on the subject: hasn't this split completely
> >>>>broken the statistics about backend-initiated writes?
> >>>Yes, it seems to have done just that.
> >>This implies that nobody has done pull-the-plug testing on either
> >>HEAD or 9.2 since the checkpointer split went in (2011-11-01),
> >>because even a modicum of such testing would surely have shown that
> >>we're failing to fsync a significant fraction of our write traffic.
> >>
> >>Furthermore, I would say that any performance testing done since
> >>then, if it wasn't looking at purely read-only scenarios, isn't
> >>worth the electrons it's written on. In particular, any performance
> >>gain that anybody might have attributed to the checkpointer splitup
> >>is very probably hogwash.
> >>
> >>This is not giving me a warm feeling about our testing practices.
> >Is there any part of this that the buildfarm, or some other automation
> >framework, might be able to handle?
> >
>
> I'm not sure how you automate testing a pull-the-plug scenario.
I have a dim memory of how the FreeBSD project was alleged to have
done it, namely by rigging a serial port (yes, it was that long ago)
to the power supply of another machine and randomly cycling the power.
> The buildfarm is not at all designed to test performance. That's why
> we want a performance farm.
Right. Apart from hardware, what are we stalled on?
Cheers,
David.
--
David Fetter <david(at)fetter(dot)org> http://fetter.org/
Phone: +1 415 235 3778 AIM: dfetter666 Yahoo!: dfetter
Skype: davidfetter XMPP: david(dot)fetter(at)gmail(dot)com
iCal: webcal://www.tripit.com/feed/ical/people/david74/tripit.ics
Remember to vote!
Consider donating to Postgres: http://www.postgresql.org/about/donate
From | Date | Subject | |
---|---|---|---|
Next Message | Andrew Dunstan | 2012-07-23 12:56:38 | Re: Checkpointer split has broken things dramatically (was Re: DELETE vs TRUNCATE explanation) |
Previous Message | Andrew Dunstan | 2012-07-23 12:29:16 | Re: Checkpointer split has broken things dramatically (was Re: DELETE vs TRUNCATE explanation) |
From | Date | Subject | |
---|---|---|---|
Next Message | Andrew Dunstan | 2012-07-23 12:56:38 | Re: Checkpointer split has broken things dramatically (was Re: DELETE vs TRUNCATE explanation) |
Previous Message | Andrew Dunstan | 2012-07-23 12:29:16 | Re: Checkpointer split has broken things dramatically (was Re: DELETE vs TRUNCATE explanation) |