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

Tue Jan 3 05:54:56 CST 2023

On Tue, Jan 3, 2023 at 12:48 AM 김성익 <ksi2443 at gmail.com> wrote:

> I got more questions so I resend this email with more questions.
>
> 1.After reconfigure by
> ./arch-main-debug/lib/petsc/conf/reconfigure-arch-main-debug.py
> --with-debugging=0 --PETSC_ARCH=arch-main-opt ,
> I tried to build my code.
>
> But I got an error as below
> [image: image.png]
> How can I fix this?
>

You reconfigured with PETSC_ARCH=arch-main-opt, but your build is using
"arch-linux-c-opt". Why are you changing it?

>
> 2.
>
> CFLAGS       = -O3
> FFLAGS       =
> CPPFLAGS         =
> FPPFLAGS         =
> COPTFLAGS        = -march=native
>
>
> 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
>
> Upper makefile is just for build my own code not for src of petsc.
> In this case, also has problem as your comments?
>

I do not understand your question.

>
> 3.  I have no such processors. Where can I find benchmark information
> about STREAMS?
>  I mean I don't have such various processors. So I just wondering the
> results of STREAMS each processors (already existing results of various
> processors).
> Can anyone have results of benchmark of various desktop systems?
>

There are catalogues of STREAMS results online.

  Thanks,

     Matt

> Thanks,
> Hyung Kim
>
>
>
>
>
> 2023년 1월 3일 (화) 오후 2:19, 김성익 <ksi2443 at gmail.com>님이 작성:
>
>> After reconfigure by
>> ./arch-main-debug/lib/petsc/conf/reconfigure-arch-main-debug.py
>> --with-debugging=0 --PETSC_ARCH=arch-main-opt ,
>> I tried to build my code.
>>
>> But I got an error as below
>> [image: image.png]
>> How can I fix this?
>>
>>
>>
>>
>> 2023년 1월 3일 (화) 오전 4:05, Barry Smith <bsmith at petsc.dev>님이 작성:
>>
>>>
>>>
>>> On Jan 2, 2023, at 9:27 AM, 김성익 <ksi2443 at gmail.com> wrote:
>>>
>>> There are more questions.
>>>
>>> 1. Following your comments, but there is an error as below.
>>> <image.png>
>>> How can I fix this?
>>>
>>>
>>>    The previous value of PETSC_ARCH was not arch-main-debug do ls
>>> $PETSC_DIR and locate the directory whose name begins with arch- that will
>>> tell you the previous value used for PETSC_ARCH.
>>>
>>>
>>> 2. After changing the optimized build, then how can I set the debug mode
>>> again?
>>>
>>>
>>>    export PETSC_ARCH=arch- whatever the previous value was and then
>>> recompile your code (note you do not need to recompile PETSc just your
>>> executable).
>>>
>>>
>>> 3.Following your comments, the new makefile is as below. Is it right?
>>> CFLAGS       = -O3
>>> FFLAGS       =
>>> CPPFLAGS         =
>>> FPPFLAGS         =
>>> COPTFLAGS        = -march=native
>>>
>>>
>>> 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
>>>
>>>
>>> Best not to set these values in the makefile at all because they will
>>> affect all compilers. Just set them with ./configure CCOPTFLAGS="-O3
>>> -march=native"
>>>
>>>
>>>
>>> 4. I have no such processors. Where can I find benchmark information
>>> about STREAMS?
>>>
>>>
>>>   do make mpistreams in PETSC_DIR
>>>
>>>
>>>
>>>
>>> Thanks,
>>> Hyung Kim
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>> 2023년 1월 2일 (월) 오후 11:03, Matthew Knepley <knepley at gmail.com>님이 작성:
>>>
>>>> On Mon, Jan 2, 2023 at 4:16 AM 김성익 <ksi2443 at gmail.com> wrote:
>>>>
>>>>> 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?
>>>>>
>>>> Suppose your current arch is named "arch-main-debug". Then you can make
>>>> an optimized version using
>>>>
>>>>   cd $PETSC_DIR
>>>>   ./arch-main-debug/lib/petsc/conf/reconfigure-arch-main-debug.py
>>>> --with-debugging=0 --PETSC_ARCH=arch-main-opt
>>>>
>>>>
>>>>> 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
>>>>>
>>>>
>>>> You could dp this, but that only changes it for that directory. It is
>>>> best to do it by reconfiguring.
>>>>
>>>>
>>>>> 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?
>>>>>
>>>> You can add --COPTFLAGS="<user flags>" with any flags you want to the
>>>> configure.
>>>>
>>>> 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.)
>>>>>
>>>>
>>>> A good guide is to run the STREAMS benchmark on the processor. PETSc
>>>> performance closely tracks that.
>>>>
>>>>   Thanks,
>>>>
>>>>      Matt
>>>>
>>>>
>>>>>
>>>>>
>>>>> Thanks,
>>>>>
>>>>> Hyung Kim
>>>>>
>>>>
>>>>
>>>> --
>>>> What most experimenters take for granted before they begin their
>>>> experiments is infinitely more interesting than any results to which their
>>>> experiments lead.
>>>> -- Norbert Wiener
>>>>
>>>> https://www.cse.buffalo.edu/~knepley/
>>>> <http://www.cse.buffalo.edu/~knepley/>
>>>>
>>>
>>>

-- 
What most experimenters take for granted before they begin their
experiments is infinitely more interesting than any results to which their
experiments lead.
-- Norbert Wiener

https://www.cse.buffalo.edu/~knepley/ <http://www.cse.buffalo.edu/~knepley/>
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