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retroman
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PostPosted: Wed May 16, 2007 12:04 pm    Post subject: Optimum make.conf values Reply with quote

Ive been working on some benchmarks to find the best compile flags for some of my systems. Here is the results for my Ultra60 2x 450mhz processors 512mb ram
Each test was condicted multiple times

"time emerge nano"

CFLAGS="-O3 -mcpu=ultrasparc -mtune=ultrasparc"
2m9.138
1m59.214
1m59.600
1m58.137


CFLAGS="-O3 -mcpu=ultrasparc -mtune=ultrasparc"
MAKEOPTS="-j3"
1m44.968
1m51.632
1m42.577
1m45.114


CFLAGS="-O3 -mcpu=ultrasparc -mtune=ultrasparc"
MAKEOPTS="-j4"
1m43.481
1m43.053
1m43.425
1m43.069


CFLAGS="-O2 -mcpu=ultrasparc -mtune=ultrasparc"
MAKEOPTS="-j4"
1m39.974
1m42.018
1m40.040
1m41.804

CFLAGS="-O2 -mcpu=ultrasparc -mtune=ultrasparc"
MAKEOPTS="-j3"
1m35.294
1m39.816
1m40.409
1m42.369


CFLAGS="-O2 -mcpu=ultrasparc -mtune=ultrasparc -fomit-frame-pointer"
MAKEOPTS="-j3"
1m35.151
1m39.411
1m39.271
1m40.966



CFLAGS="-O2 -mcpu=ultrasparc -mtune=ultrasparc -pipe -fomit-frame-pointer"
MAKEOPTS="-j3"
1m39.887
1m38.091
1m39.875
1m37.561


the -pipe flag would probably further spped up the compile time if I had more memory, Im also not sure if fomit-frame-pointer has any great benefit on a sparc64 processor
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Ferris
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PostPosted: Wed May 16, 2007 12:16 pm    Post subject: Reply with quote

Neither -O3 nor -fomit-frame-pointer is generally a good idea on sparc.

Regards,
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gust4voz
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Joined: 09 Sep 2003
Posts: 373
Location: Buenos Aires, Argentina

PostPosted: Wed May 16, 2007 1:09 pm    Post subject: Reply with quote

Also "time emerge nano" is only measuring how fast it builds - not how fast it works.
I assume you want the fastest binaries, not the fastest build times.
Usually the job option for MAKEOPTS is cpu+1, so -j3 for 2 processors and so on.
As Ferris says, -O3 and -fomit-frame-pointer are really not good ideas on sparc, if you trigger some build/run issue with those we'll just close the bug with "lower your settings to a sane value".
I'm using CFLAGS="-mcpu=ultrasparc -mtune=ultrasparc -mvis -Wa,-Av8plusa -O2 -pipe" and didn't hit issues on stable, though some people seemed to have hit some from what i've read - the ones i've seen in the past are usually related to the linker flags being pass to the wrong places.
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retroman
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PostPosted: Wed May 16, 2007 2:21 pm    Post subject: Reply with quote

Im not familiar with these flags what do they do?

-mvis -Wa,-Av8plusa


thanx

jordan
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gust4voz
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PostPosted: Wed May 16, 2007 4:28 pm    Post subject: Reply with quote

-mvis enables the VIS instruction set.
-Wa,-Av8plusa is a linker directive since sometimes, with -mvis, things get confused and build 64-bit userland stuff (which won't work) - basically it forces 32-bit.
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Gustavo Zacarias
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retroman
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PostPosted: Wed May 16, 2007 8:58 pm    Post subject: Reply with quote

are there any notable performance gains with these? It doesnt matter if it breaks compatibility with other computers. This is the only ultra 60 I have.
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