From: Simon Waters <simonw@zynet.net>
To: pgsql-performance@postgresql.org
Subject: Re: Need help with 8.4 Performance Testing
Date: Tue, 9 Dec 2008 13:58:43 +0000
Message-ID: <200812091358.43741.simonw@zynet.net> (raw)
In-Reply-To: <493E6DBE.2040605@verizon.net>
References: <200812071138.01215.josh@agliodbs.com>
<Pine.GSO.4.64.0812082225470.13669@westnet.com>
<493E6DBE.2040605@verizon.net>
On Tuesday 09 December 2008 13:08:14 Jean-David Beyer wrote:
>
> and even if they can, I do not know if postgres uses that ability. I doubt
> it, since I believe (at least in Linux) a process can do that only if run
> as root, which I imagine few (if any) users do.
Disclaimer: I'm not a system programmer...
I believe that at Linux kernel revision 2.6.8 and before processes need Posix
capability CAP_IPC_LOCK, and 2.6.9 and after they need CAP_IPC_LOCK to lock
more than RLIMIT_MEMLOCK.
It is a capability, so a process can run as any user assuming it is started
with or gained the capability.
No idea if Postgres uses any of this, other than to protect security of
certain password operations there is probably not much point. If key parts of
your database are being paged out, get more RAM, if idle parts of your
database are paged out, you probably could more usefully apply that RAM for
something else.
The Varnish cache design is the place to look for enlightenment on relying on
the kernel paging (using memory mapped files) rather than trying to do it
yourself, but then a proxy server is a lot simpler than a RDBMS. That said,
Varnish is fast at what it does (reverse HTTP proxy) !
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To: pgsql-performance@postgresql.org
Cc: simonw@zynet.net
Subject: Re: Need help with 8.4 Performance Testing
In-Reply-To: <200812091358.43741.simonw@zynet.net>
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