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From: litter AT null DOT net
Subject: Bash / cygwin process spawning (?) performance very slow
Message-ID: <5602684A.5090108@null.net>
Date: Wed, 23 Sep 2015 10:52:26 +0200
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Hi all,

I noticed that doing simple loops in Bash takes unexpectedly long under Cygwin on a Windows XP 32 bit machine 
(CYGWIN_NT-5.1 <machine> 2.2.1(0.289/5/3) 2015-08-20 11:40 i686 Cygwin)

I already followed the FAQ advice in trying to determine general causes, and made a 'shadow' copy of /etc/passwd as described.
My PATH does not contain references to network shares.

Still quite normal commands take a long time e.g. 
time cat some-file | while read i;do echo $i;/bin/true;done

real 1m44.953s
user 0m9.599s
sys 1m36.865s

for a file of 167 lines. Process Explorer showed a CPU load of 20% on bash.exe, which was almost completely Kernel time.
Is such high Kernel load normal?

I know it's a bit like comparing apples to oranges, but I run the SAME command from the same disk, from within a Debian 7 486 Linux on VirtualBox (!) on the same machine, it gave
real 0m3.871s
user 0m0.160s
sys 0m3.292s

So even running in emulator, real/user/sys time are about 30/60/30 times faster. That's quite shocking.
Is this performance to be expected? That would make it an obvious choice to switch to VirtualBox on this machine.

Thanks,
Paul

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