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Date: Thu, 28 Nov 2002 15:07:40 +0100
From: thomas <tom AT huno DOT net>
Reply-To: thomas <cygwin AT cygwin DOT com>
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Message-ID: <1988826218.20021128150740@huno.net>
To: thomas <cygwin AT cygwin DOT com>
Subject: Re: pipe performance problem
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Ok now i really found the problem. If i always return from
fhandler_base::ready_for_read with 1 at the first line and skip all the
checks in there everything works.

$ time cat test.iso | nice -0 dd of=/dev/null
352512+0 records in
352512+0 records out

real    0m5.528s
user    0m2.155s
sys     0m3.342s

$ time cat test.iso | nice --1 dd of=/dev/null
352512+0 records in
352512+0 records out

real    0m4.188s
user    0m1.592s
sys     0m2.452s


nice --1 is faster like it should be. Just to be on the safe side i also
did:

$ cat test.iso | nice --1 dd of=test1
$ cat test.iso | nice -0 dd of=test0

$ diff -q -s --binary test0 test1
Files test0 and test1 are identical

$ diff -q -s --binary test0 test.iso
Files test0 and test.iso are identical


So that workaround works perfectly for my purposes. But i guess the
checks were put in there for good reason to fix sth. that happened on
the way. Just that it broke sth. else.
I already did some mkisofs | cdrecord checks and it also works
perfectly!

thomas


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