From: Achilleas Mantzios <achill@matrix.gatewaynet.com>
To: pgsql-admin@postgresql.org
Subject: Re: Postgresql 9.0.2 explain analyze very slow (10x), compared to actual query time
Date: Thu, 13 Jan 2011 12:17:52 +0200
Message-ID: <201101131217.53575.achill@matrix.gatewaynet.com> (raw)
In-Reply-To: <AANLkTimpcZxtxcTbc=8RFGj7HF=UKBtkksCFN6ooXGTc@mail.gmail.com>
References: <201101111753.22602.achill@matrix.gatewaynet.com>
<201101121817.11143.achill@matrix.gatewaynet.com>
<AANLkTimpcZxtxcTbc=8RFGj7HF=UKBtkksCFN6ooXGTc@mail.gmail.com>
Óôéò Wednesday 12 January 2011 21:17:00 ï/ç Alex Hunsaker Ýãñáøå:
> 2011/1/12 Achilleas Mantzios <achill@matrix.gatewaynet.com>:
>
> >
> > Changed that to smth like: micros_total = micros_total + (double) micros;
> > instead of the printf to beat any compiler optimization, and still linux runs at light speed:
> > FBSD_TEST : user 0.089s, sys 1.4s
> > FBSD_DEV : user 0.183s, sys 3.8s
> > LINUX_PROD : user 0.168s, sys 0s
> > (regarding that gettimeofday is a syscall in FreeBSD, and that sys time is 0 for linux, makes me think some optimization is being done)
>
> At least on x86_64, linux will use a vsyscall (v for virtual) for
> gettimeofday which does not actually need to enter/exit the kernel.
> That probably explains a large part of the speed difference here.
>
Thanx, thats the ARCH (x86_64) of our linux system.
--
Achilleas Mantzios
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To: pgsql-admin@postgresql.org
Cc: achill@matrix.gatewaynet.com
Subject: Re: Postgresql 9.0.2 explain analyze very slow (10x), compared to actual query time
In-Reply-To: <201101131217.53575.achill@matrix.gatewaynet.com>
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