Date: Thu, 2 Dec 2004 16:59:36 -0500 From: Garance A Drosihn <drosih@rpi.edu> To: Rob <spamrefuse@yahoo.com>, freebsd-stable@freebsd.org Subject: Re: make -j$n buildworld : use of -j investigated Message-ID: <p0620072abdd533f841e6@[128.113.24.47]> In-Reply-To: <41A2C5C0.3080908@yahoo.com> References: <41A2C5C0.3080908@yahoo.com>
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At 2:08 PM +0900 11/23/04, Rob wrote:
>Hi,
>
>I have tested following with FreeBSD 5.3-Stable.
>
>On several different PCs I have used
> make -j$n buildworld
>with $n ranging from 1 to 9.
>
>Although people suggest "-j4" as optimal in general
>case, I have come to a very different conclusion...
So, I finally got around to doing some timings on my newest PC.
It is a AMD Athlon(tm) XP 3000+ (2166.43-MHz 686-class CPU) with
1-gig of memory, and fast SATA disks. It was certainly different
that what I saw on my previous single-CPU systems. Roughly:
Real User Sys Max-LA
2670.86 2071.66 543.49 1.25 buildworld
2751.60 2085.95 603.69 1.35 -j1 buildworld
2825.87 2137.19 637.15 5.58 -j2 buildworld
2887.03 2158.60 648.37 11.85 -j3 buildworld
2856.75 2156.48 647.43 19.06 -j4 buildworld
2851.71 2154.39 647.19 25.43 -j5 buildworld
2850.92 2155.40 646.19 31.59 -j6 buildworld
2850.07 2153.77 648.41 36.19 -j7 buildworld
2852.64 2155.74 647.82 47.00 -j8 buildworld
2851.66 2153.43 650.23 53.51 -j9 buildworld
(I've actually done multiple runs of each, but they all show about
the same numbers). I had a separate session doing 'uptime's every
30 seconds, and the "Max-LA" column is the maximum load-average
that was seen by that separate session.
Apparently the faster disks made a much bigger difference than I
had expected to see.
--
Garance Alistair Drosehn = gad@gilead.netel.rpi.edu
Senior Systems Programmer or gad@freebsd.org
Rensselaer Polytechnic Institute or drosih@rpi.edu
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