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Bug 41549

Summary: [jni] very slow jni code callbacks
Product: gcc Reporter: Herman ten Brugge <hermantenbrugge>
Component: javaAssignee: Not yet assigned to anyone <unassigned>
Status: RESOLVED WONTFIX    
Severity: normal CC: d, gcc-bugs, java-prs
Priority: P3    
Version: 4.4.1   
Target Milestone: ---   
Host: x86_64-unknown-linux-gnu Target:
Build: Known to work:
Known to fail: Last reconfirmed:

Description Herman ten Brugge 2009-10-02 15:48:57 UTC
See mailing list:
http://gcc.gnu.org/ml/java/2009-09/msg00030.html

I have a problem with jni code callbacks.
I have attached some code that shows the problem.
The result of this code is:


# results on fedora 11
#  gcc/gcj 4.4.1
#  kernel 2.6.30.5-43.fc11.x86_64
#  openjdk fedora-29.b16.fc11-x86_64
#
#                       open jdk        gcj
# no_jni                 1.48               7.46        (  5 times slower)
# jni                   66.70           17140.00        (257 times slower)


So when not using jni in this case gcj is 5 times slower.
I suspect the jit compiler does a good for this small sample.


The code with jni calls is however 257 timer slower. I really
did not expect that. I also tried other java vm and they all
have much better performance. So I expect a problem in the
gcj library.


When I use oprofile I see at lot of calls to execute_cfa_program
and _Unwind_IteratePhdrCallback.
Comment 1 Andrew Pinski 2016-09-30 22:48:41 UTC
Closing as won't fix as the Java front-end has been removed from the trunk.