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Re: pipe performance problem
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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