Talk:HOWTO Migrate to GCC 3.4
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[edit] What is the default gentoo compiler?
I have not been using Gentoo for some time so I dont know. Does it use gcc-3.4 yet?
gcc-3.4 has been marked stable on x86 recently. For other platforms see [1].
[edit] Povray benchmark
Results with Povray 3.6-r1 (scenes/advanced/benchmark.ini) on AMD Athlon64 3200+ 2,2GHz (not overclocked), 512MB 400MHz DDRAM (PC3200), gentoo-dev-sources-2.6.10-r1
Compiled with GCC-3.3.4
Total Scene Processing Times Parse Time: 0 hours 0 minutes 2 seconds (2 seconds) Photon Time: 0 hours 0 minutes 34 seconds (34 seconds) Render Time: 0 hours 25 minutes 29 seconds (1529 seconds) Total Time: 0 hours 26 minutes 5 seconds (1565 seconds)
Compiled with GCC-3.4.3-r1
Total Scene Processing Times Parse Time: 0 hours 0 minutes 1 seconds (1 seconds) Photon Time: 0 hours 0 minutes 32 seconds (32 seconds) Render Time: 0 hours 23 minutes 34 seconds (1414 seconds) Total Time: 0 hours 24 minutes 7 seconds (1447 seconds)
A 7,5% gain
[edit] Glibc & Unecessary compiles
I dont see any reason why a -3.4 version was appended to it. I'm the original author and I don't recall putting that in there...heh, maybe I did :p Generally it's best to recompile Glibc with the current compiler, but glibc's current version is 2.3.4 and I fail to see why a version would be applied to it. Fixed now.
Also, I removed some very unnecessary emerges. Re-emerging the system twice, then proceeding to emerge world twice? By anyone's standards that's just crazy...if your system is so broken that it cannot compile a package consecutively without producing bad output you shouldn't be running a from-source distro like Gentoo.
[edit] gcc-config
When following this HOWTO, it made a blocking situation: !!! All ebuilds that could satisfy ">=sys-devel/gcc-config-1.3.9" have been masked. [...] !!! (dependency required by "sys-libs/glibc-2.3.4.20050125" [ebuild])
If other people have experienced this, I suggest we add 'echo "sys-devel/gcc-config ~x86" >> /etc/portage/package.keywords' in the appropriate spot
- Will do that. Did not know gcc-config was an emerge-able script.
[edit] ccache
If you use ccache - don't forget to run "ccache -C"! In other case you may have lot's of compilation failures.
[edit] clearing the cache
Clearing the cache should not be needed if ccache's manpage is correct.
Read ccache's man page: Every cached file contains information about the compiler used to generate that object.
Either declaring clearing the cache as needed is a fairytale or ccache's doc is wrong!
So if you keep the old GCC, you may be interested in keeping the old cache contents. If you deinstall the old GCC, clearing the cache just is getting rid of unneeded files.
If compiles go wrong before clearing the cache and succeed after clearing the cache, this has to be investigated more deeply because it contradicts ccache's doc, especially the part in the manpage about what information is coded into the hash value... ccache's author shold be informed about such a misbehaviour or doc-bug...
yeti, 2005-10-27
