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X-WM-Posted-At: avacado.atomice.net; Mon, 21 Oct 02 23:05:51 +0100
From: "Chris January" <chris AT atomice DOT net>
To: "Cygwin AT Cygwin DOT Com" <cygwin AT cygwin DOT com>
Subject: RE: Copy-on-write fork
Date: Mon, 21 Oct 2002 23:05:51 +0100
Message-ID: <LPEHIHGCJOAIPFLADJAHKEFLCPAA.chris@atomice.net>
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> > A test program and statistics are shown below which clearly
> show Cygwin's
> > fork implementation in the lead.
>
> how much memory did your programs allocate prior to fork()ing?
> copy-on-write might only apply to applications with high memory-usage.
>
> another thing i didn't understand was, why you took a the real-time for
> mesuring?
>
> i can do "time mc" and exit mc after 10sec and time will show real-time
> 10sec but the _real cpu-time_ is below <1sec.
> the CPU-times consumed by the copy-on-write-implemention is _lower_ than
> cygwin-implementation's CPU-time.
>
> so why are you guys worried?

Repeat after me: don't open old threads.
However I'll let you off this once, because you are using a newsreader and
I've made the same mistake before.

If you think copy on write is faster, then feel free to do some tests. A
website with some nice pretty graphs, and source code would be great. I can
send you some code for starters, I'm sure Chris Faylor has some around too.
It may well be that both of us were simply not doing the right tests.
My tests were based on timing a single process that allocated a large region
of memory, then forked in a loop. Each forked process touched the memory
allocated earlier by overwriting it with a random value.

Chris


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