On 5/20/2013 4:01 AM, Alan W. Irwin wrote:
On 2013-05-20 07:51+0200 marco atzeri wrote:
the slowness at startup on cywin is mainly due the fork
implementation
http://cygwin.com/faq/faq-nochunks.html#faq.api.fork
unfortunately windows makes a real fork implementation very inefficient.
Hi Marco:
Your explanation sounds reasonable since it appears all new processes
are started with fork, but do you have a reference for that conclusion
that gives more specifics? All the above URL says is that fork can be
"a little slow" on Cygwin with no timing specifics.
Assuming this is the complete explanation for Cygwin startup latency,
I assume it is also the explanation of the MSYS bash.exe startup
latency (factor of 25 slowdown for startup) for all commands that I
found on Wine (a version of Windows whose developers try very hard to
make an exact clone of Microsoft Windows). The inefficient fork
explanation would also predict that commands executed under bash.exe
on Microsoft Windows would also show the same startup latency issue.
Can somebody with access to MSYS bash.exe on Microsoft Windows verify
that startup latency by timing "--version" options for standard
commands such as cmake? If such times on a normal PC are hundreds of
milliseconds than you have confirmed the issue, but if they are only a
few milliseconds (8 on Linux, for example, for my entry level PC
hardware), then you have shown the issue doesn't exist for Microsoft
Windows which would contradict the above inefficient fork explanation.
sh-3.1$ time gcc --version
gcc.exe (4.3.3-tdm-1-dw2 mingw32) 4.3.3-dw2
Copyright (C) 2008 Free Software Foundation, Inc.
This is free software; see the source for copying conditions. There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
real 0m0.028s
user 0m0.000s
sys 0m0.015s
Kenneth
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