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Old 07-11-2011, 12:25 PM   #196
Iņigo
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Posts: 730
Karma: 72743
Join Date: Feb 2008
Location: Here or there
Device: iRex iLiad, iRex DR800S. K4NT. Kobo Aura, Aura One, Libra 2.
Quote:
Originally Posted by lacol View Post
Iņigo, you mention in the readme of dr800+ that you improved performance at some point by applying optimizations during compilation. Do you know if Irex applied the same optimizations in compiling the original rc3 firmware ?

In other words, would completely recompiling from source the 2.0-RC3 firmware result in a performance increase even when doing no modification to the source, but using the compiler optimizations mentionned in the readme of dr800+ ?

And by the way, how does one apply those optimization ? Is this something that should appear in the makefile ? I can't seem to find any trace of them in any configure.ac or makefile.am file in the source of your dr800+ package.
Those optimizations are passing some flags to the compiler:
"-mcpu=arm1136jf-s -mtune=arm1136jf-s -O3 -funroll-loops"
They generate special code for the ARM CPUs DR ereaders have.

They don't appear in the sources, as I added next lines to my environment-setup initialization script:
Code:
export CFLAGS="-mcpu=arm1136jf-s -mtune=arm1136jf-s -O3 -funroll-loops"
export CXXFLAGS="-mcpu=arm1136jf-s -mtune=arm1136jf-s -O3 -funroll-loops"
I'm not sure but I think they were not applied in IREX firmware, as same sources result in different binary size. Maybe Gertjan could add more here.

I think I noted some speed improvement when I compiled some code: ctb, popupmenu, ermetadb... But I'm not sure it will make DR faster. Anyway, not more than 2-3%

Iņigo
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