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GCC celebrates 25 years with the 4.7.0 release

GCC celebrates 25 years with the 4.7.0 release

Posted Mar 23, 2012 2:33 UTC (Fri) by scientes (guest, #83068)
In reply to: GCC celebrates 25 years with the 4.7.0 release by PaXTeam
Parent article: GCC celebrates 25 years with the 4.7.0 release

This is for linux modules right?


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GCC celebrates 25 years with the 4.7.0 release

Posted Mar 23, 2012 8:18 UTC (Fri) by PaXTeam (subscriber, #24616) [Link]

nope ;)
$ size linux-3.3-pax*/vmlinux
   text            data     bss      dec            hex filename
13552485        9980097 3715072 27247654        19fc426 linux-3.3-pax-clang/vmlinux
13434172        7919561 3796992 25150725        17fc505 linux-3.3-pax-lto/vmlinux
14145894        9323349 3776512 27245755        19fbcbb linux-3.3-pax/vmlinux

GCC celebrates 25 years with the 4.7.0 release

Posted Mar 23, 2012 9:08 UTC (Fri) by engla (guest, #47454) [Link]

Any performance improvements with LTO?

GCC celebrates 25 years with the 4.7.0 release

Posted Mar 23, 2012 10:11 UTC (Fri) by PaXTeam (subscriber, #24616) [Link]

i didn't do any benchmarks so i can't tell. note also that the above kernels don't have the exact same config due to some yet-to-be-fixed deficiences with LTO or clang (e.g., the LTO kernel above didn't have KALLSYMS/KPROBES/FUNCTION_TRACER enabled and the clang one didn't use the PaX gcc plugins for obvious reasons).

GCC celebrates 25 years with the 4.7.0 release

Posted Mar 25, 2012 1:07 UTC (Sun) by nix (subscriber, #2304) [Link]

I frankly doubt you'd see enormous improvements in non-pathological benchmarks anyway, because the kernel is not the predominant consumer of CPU time in most benchmarks, and LTO will do nothing to improve locality of reference or any of the heaps of algorithmic things which a kernel has to deal with and which really do take time. You'd probably see an improvement from reduction in icache pressure though, but I have no idea how big it might be. Probably minimal, but one can hope.

As always, the numbers will tell.

GCC celebrates 25 years with the 4.7.0 release

Posted Mar 23, 2012 16:04 UTC (Fri) by slashdot (guest, #22014) [Link]

What's causing the massive .data size differences?

GCC celebrates 25 years with the 4.7.0 release

Posted Mar 23, 2012 23:58 UTC (Fri) by PaXTeam (subscriber, #24616) [Link]

some of it is due to the .config difference, some of it is genuine LTO but i don't have numbers for same .config compilations now, sorry.

GCC celebrates 25 years with the 4.7.0 release

Posted Apr 6, 2012 18:33 UTC (Fri) by nathanwm (guest, #83115) [Link]

Could you guys release the clang patches for the kernel? I plan on implementing a distro based on llvm, mclinker, toybox and various other bits with a preference for code quality.

GCC celebrates 25 years with the 4.7.0 release

Posted Apr 7, 2012 21:12 UTC (Sat) by PaXTeam (subscriber, #24616) [Link]

oh boy, next time better email me directly please, it's only by luck that i caught this in rss ;). as for the patches, i did submit them last year to the cfe-dev list, only a few things changed since. if you're in a hurry for an up-to-date version (against linux 3.3.1) then email me please (lwn doesn't reveal your email address).

one of these days i'd also like to post an update now that llvm/clang 3.1 is nearing completion, i just have to finish my default argument support patch for asm macros so that we may then be able to use integrated-as for linux.

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