[petsc-users] Question - about the 'Hint for performance tuning'

[김성익]

Hello,

Happy new year!!



I have some questions about “Hint for performance tuning” in user guide of
petsc.



1.     In the “Performance Pitfalls and Advice” section, there are 2 modes
“debug” and “optimized builds. My current setup is debug mode. So I want to
change for test the performance the optimized build mode. However, if I
configure again, does the existing debug mode disappear? Is there any way
to coexist the 2 modes and use them in the run the application?



2.     In the guide, there are some paragraphs about optimization level of
compiler. To control the optimization level of compiler, I put the ‘-O3’ as
below. Is this right??

CFLAGS       = -O3

FFLAGS       =

CPPFLAGS         =

FPPFLAGS         =



app : a1.o a2.o a3.o a4.o

   $(LINK.C) -o $@ $^ $(LDLIBS)



include ${PETSC_DIR}/lib/petsc/conf/rules

include ${PETSC_DIR}/lib/petsc/conf/test



3.     In the guide, user should put ‘-march=native’ for using AVX2 or
AVX-512. Where should I put the ‘-march=native’ for using AVX?



4.     After read the “Hint for performance tuning” I understood that for
good performance and scalability user should use the multiple node and
multiple socket . However, before composing cluster system, many users just
can use desktop system.
In that case, between intel 13th i9 and amd ryzen 7950x, can the 7950x,
which has an arichitecture similar to the server processor, be more
suitable for petsc? (Because the architecture of intel desktop cpu is
big.little.)





Thanks,

Hyung Kim
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