Re: 7.3.8 under FC3 takes excessive semaphores?

From: "Mark Cave-Ayland" <m(dot)cave-ayland(at)webbased(dot)co(dot)uk>
To: "'Tom Lane'" <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: 7.3.8 under FC3 takes excessive semaphores?
Date: 2005-02-01 12:40:09
Message-ID: 9EB50F1A91413F4FA63019487FCD251DADE6@WEBBASEDDC.webbasedltd.local
Views: Raw Message | Whole Thread | Download mbox | Resend email
Thread:
Lists: pgsql-hackers


> -----Original Message-----
> From: Tom Lane [mailto:tgl(at)sss(dot)pgh(dot)pa(dot)us]
> Sent: 31 January 2005 16:35
> To: Mark Cave-Ayland
> Cc: pgsql-hackers(at)postgresql(dot)org
> Subject: Re: [HACKERS] 7.3.8 under FC3 takes excessive semaphores?

(cut)

> Judging by the symptoms, you have built a version with what
> we now call --disable-spinlocks; that is, it didn't figure
> out how to do assembly TAS on your platform and fell back to
> using SysV semaphores for spinlocks. Quite aside from the
> drain on semaphores, the performance is going to be
> spectacularly bad, so you'd better fix that.
>
> regards, tom lane

Hi Tom,

I'd just about managed to come to the same conclusion before your email
arrived by spending the afternoon with gdb tracing into the LWLock code :)

I've just installed 7.4.6 on the same box and this time the spinlocks are
correctly picked up and everything works as expected. I think rather than
fixing the 7.3.x source, we'll take the plunge and plan for a complete dump
and restore of the database cluster over a weekend.

Many thanks,

Mark.

------------------------
WebBased Ltd
South West Technology Centre
Tamar Science Park
Plymouth
PL6 8BT

T: +44 (0)1752 791021
F: +44 (0)1752 791023
W: http://www.webbased.co.uk

In response to

Responses

Browse pgsql-hackers by date

  From Date Subject
Next Message a_ogawa 2005-02-01 13:06:43 Re: FunctionCallN improvement.
Previous Message Peter Eisentraut 2005-02-01 12:03:35 Re: 7.2.7 -> 8.0.1 Bundles Ready ...