From: Jim C. Nasby <jnasby@pervasive.com>
To: David Lang <dlang@invendra.net>
Cc: Mark Liberman <mliberman@mixedsignals.com>
Cc: pgsql-performance@postgresql.org
Subject: Re: Help in avoiding a query 'Warm-Up' period/shared buffer
Date: Thu, 5 Jan 2006 21:14:21 -0600
Message-ID: <20060106031421.GM43311@pervasive.com> (raw)
In-Reply-To: <Pine.LNX.4.62.0601051848510.11046@qnivq.ynat.uz>
References: <200601041449.43557.mliberman@mixedsignals.com>
<dpk922$slo$1@news.hub.org>
<200601051815.36181.mliberman@mixedsignals.com>
<Pine.LNX.4.62.0601051848510.11046@qnivq.ynat.uz>
On Thu, Jan 05, 2006 at 06:50:22PM -0800, David Lang wrote:
> On Thu, 5 Jan 2006, Mark Liberman wrote:
>
> >Obviously, I will be testing this - but it might take a few days, as I
> >haven't
> >figure out how to simulate the "period of inactivity" to get the data
> >flushed
> >out of the cache ... so I have to run this each morning.
>
> cat large_file >/dev/null
>
> will probably do a pretty good job of this (especially if large_file is
> noticably larger then the amount of ram you have)
The following C code is much faster...
/*
* $Id: clearmem.c,v 1.1 2003/06/29 20:41:33 decibel Exp $
*
* Utility to clear out a chunk of memory and zero it. Useful for flushing disk buffers
*/
int main(int argc, char *argv[]) {
if (!calloc(atoi(argv[1]), 1024*1024)) { printf("Error allocating memory.\n"); }
}
Compile it and then pass in the number of MB of memory to allocate on
the command line.
--
Jim C. Nasby, Sr. Engineering Consultant jnasby@pervasive.com
Pervasive Software http://pervasive.com work: 512-231-6117
vcard: http://jim.nasby.net/pervasive.vcf cell: 512-569-9461
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To: pgsql-performance@postgresql.org
Cc: jnasby@pervasive.com, dlang@invendra.net, mliberman@mixedsignals.com
Subject: Re: Help in avoiding a query 'Warm-Up' period/shared buffer
In-Reply-To: <20060106031421.GM43311@pervasive.com>
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