Profile Guided Optimization

New features which should be implemented in Porteus; suggestions are welcome. All questions or problems with testing releases (alpha, beta, or rc) should go in their relevant thread here, rather than the Bug Reports section.
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jcuk
White ninja
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Joined: 13 Mar 2011, 23:34
Location: Cambridge UK

Profile Guided Optimization

Post#1 by jcuk » 01 May 2011, 21:55

Of Interest to Code Developers here? Something I've just finished reading.

A couple of days ago:
Mozilla Devs finally succeeded in getting firefox optimizations
tuned for Linux so the performance in Linux is comparable to Windows ports.

See: Faster Linux Builds (Mozilla)
http://glandium.org/blog/?p=1975

Might be interesting to compare the Nightlies that use this Profile
Guided Optimization ( in SLAX modules? ) with the conventionally built
production binaries for Firefox.

Code bloat with -O3 used is likely if you are trying to cram as much
as possible into a small-ish LiveCD iso, but would KDE binaries benefit from
the same PGO treatment when building from source? I'm wondering how much
extra effort is needed to pick out the "low hanging fruit" of the slowest
parts of the product in an unguided unprofiled build process...

--jcuk

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fanthom
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Distribution: Porteus Kiosk
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Re: Profile Guided Optimization

Post#2 by fanthom » 04 May 2011, 17:09

thanks - i'll have a look on this:)

BTW i dont like -O3 and prefer -Os which produces smaller code and can be faster than -O3 in some scenarios:

Code: Select all

On computers with limited cache and/or memory, "-Os" may provide better performance in some cases through smaller binaries, although it is slower when using the OpenSSL library with small keys (DSA keys with less than 2048 bits on VIA C3-2, 1200 MHz and 64 kb on-die cache). 
source:
http://en.gentoo-wiki.com/wiki/Safe_Cflags

i'm using -Os for compilation of KDE-4
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