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Date: Tue, 19 Dec 2006 23:50:41 +0100
From: Christian Franke <Christian DOT Franke AT t-online DOT de>
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Subject: Re: Cygwin slower on one computer
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Magnus Holmgren wrote:

> ...
> After some more digging - and a bit of feedback off-list - I get the 
> feeling (in the cases I've noticed at least) that the speed difference 
> is mainly explained by the following reasons (in no particular order):
>
> * fork is expensive.
> * vfork is just a wrapper for fork on cygwin.
> * fork is much more expensive on AMD than on Intel.
>
> The third one is the one I'm most unsure about, as I only really have 
> data about one Intel architecture (the Pentium M). But on the AMD 
> system, the page fault delta (as reported by Process Explorer) during 
> a build is a little more than 10,000 per second, while on the Intel 
> system, the page fault delta can go to 30,000 per second.


Below are results for two PC with Intel P4 3200 ("Prescott") and 
Athlon64 3200+ ("Winchester").
Both with 1GB, WinXP SP2, Cygwin 1.5.22, Virus Scanner + Personal FW off:

Command: "time ./configure && time make" (on smartmontools source)

CPU    Intel     AMD

./configure:
real   1m09.0    5m25.8
user   0m53.5    0m54.2
sys    0m10.5    1m48.2

make:
real   0m15.3    0m25.6
user   0m10.9    0m09.3
sys    0m02.5    0m07.4


Disabling HT on Intel makes no difference.

Looks like fork is *much* more expensive on AMD. Any idea why?

Christian


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