Andrew Haley wrote: > ffileppo wrote: > >> I've been investigating about performance of java code compiled with gcj on embedded systems. >> In particular I'm interested in testing AWT/SWING application using GTK/Xorg as graphical backend >> (this is the only viable solution since QT peers are not well supported). >> >> The embedded device I've been using for testing is a PXA270 processor (armv5te) equipped with 128Mb Ram; >> running linux kernel 2.6.24 and using libgcj.so.10. GTK peers are running on Xorg, using matchbox >> as window manager. The crosscompiler on my host is gcc 4.4. >> >> During my tests I've noticed that java code using AWT/SWING (for example the test case attached at the end) >> with GTK peer cause a very high load on the cpu. >> Furthermore the applications take a lot of time to load and also the UI responsiveness is very slow. >> Using "top" I can see that CPU is always at 100% during start up (it takes about 2 minutes >> to get the application starting, Ram usage is ok). >> >> I've also noticed that using optimizations (-O2, -O3...) does not help with graphical performance. >> >> [On the same device, running WinCE and a commerical JVM (CrEme), applications have extremely better >> graphical performance] >> >> From my experience with this particual embedded system I can say that gcj has very high performance >> when dealing with non-gui tasks (e.g. array sorting) compared with most of JVMs but gui >> performance are very poor. >> >> I would like to ask your opinion about the slowness of gui applications in my setup, >> and also about viable solutions to improve this issue. >> What do you think is the bottleneck? >> >> -- libgcj itself? >> -- GTK library / GTK peer implementation in classpath? >> -- something dealing with Xorg? > > We can only speculate. > > oprofile is your friend. If you can get oprofile working on your > target system, please use it and find out if it does what you need. I did it. The answer is appended. The problem is that the program is spending almost all of the time generating stack traces, millions and millions of them. Andrew. 259512 13.5589 libgcc_s.so.1 libgcc_s.so.1 execute_cfa_program 188702 9.8592 libgcc_s.so.1 libgcc_s.so.1 _Unwind_IteratePhdrCallback 169139 8.8371 libgcc_s.so.1 libgcc_s.so.1 uw_update_context_1 155408 8.1197 libgcj.so.10.0.0 libgcj.so.10.0.0 GC_mark_from 113082 5.9083 libgcc_s.so.1 libgcc_s.so.1 uw_frame_state_for 77219 4.0345 libgcj.so.10.0.0 libgcj.so.10.0.0 _Jv_platform_gettimeofday() 65323 3.4130 libc-2.8.so libc-2.8.so dl_iterate_phdr 61075 3.1910 no-vmlinux no-vmlinux (no symbols) 55123 2.8800 libgcc_s.so.1 libgcc_s.so.1 read_encoded_value_with_base 52303 2.7327 libpthread-2.8.so libpthread-2.8.so pthread_mutex_lock 42087 2.1989 libgcj.so.10.0.0 libgcj.so.10.0.0 GC_add_to_black_list_normal 38694 2.0217 libpthread-2.8.so libpthread-2.8.so __pthread_mutex_unlock_usercnt 32618 1.7042 libc-2.8.so libc-2.8.so strlen 27568 1.4404 libgcc_s.so.1 libgcc_s.so.1 _Unwind_Backtrace 27246 1.4235 libgcj.so.10.0.0 libgcj.so.10.0.0 GC_find_start 26285 1.3733 libgcj.so.10.0.0 libgcj.so.10.0.0 _Jv_FindCore(_Jv_core_chain*, java::lang::String*) 24849 1.2983 libgcc_s.so.1 libgcc_s.so.1 _Unwind_Find_FDE 21328 1.1143 libc-2.8.so libc-2.8.so memset 18771 0.9807 libz.so.1.2.3 libz.so.1.2.3 deflate_slow 18318 0.9571 libgcc_s.so.1 libgcc_s.so.1 get_cie_encoding 16052 0.8387 libgcj.so.10.0.0 libgcj.so.10.0.0 __gcj_personality_v0 14649 0.7654 libgcj.so.10.0.0 libgcj.so.10.0.0 _Jv_StackTrace::UnwindTraceFn(_Unwind_Context*, void*) 12847 0.6712 libgcj.so.10.0.0 libgcj.so.10.0.0 GC_find_header 11533 0.6026 libgcc_s.so.1 libgcc_s.so.1 base_from_cb_data 10373 0.5420 libgcj.so.10.0.0 libgcj.so.10.0.0 GC_local_gcj_malloc 9712 0.5074 libc-2.8.so libc-2.8.so memcpy 9000 0.4702 libgcj.so.10.0.0 libgcj.so.10.0.0 _Jv_IsAssignableFrom(java::lang::Class*, java::lang::Class*) 8478 0.4430 libgcc_s.so.1 libgcc_s.so.1 uw_update_context 8216 0.4293 libz.so.1.2.3 libz.so.1.2.3 fill_window 7534 0.3936 libfreetype.so.6.3.16 libfreetype.so.6.3.16 (no symbols) 7390 0.3861 libgcj.so.10.0.0 libgcj.so.10.0.0 _Jv_MonitorExit 6617 0.3457 libgcj.so.10.0.0 libgcj.so.10.0.0 _Jv_MonitorEnter 5593 0.2922 libgcj.so.10.0.0 libgcj.so.10.0.0 bool java::lang::String::equals(java::lang::Object*) 5521 0.2885 libgcj.so.10.0.0 libgcj.so.10.0.0 _Jv_NewPrimArray 5130 0.2680 libgcj.so.10.0.0 libgcj.so.10.0.0 _Jv_CheckArrayStore 4780 0.2497 libgcj.so.10.0.0 libgcj.so.10.0.0 GC_clear_stack_inner
