Messages in this thread | | | Date | Fri, 30 Mar 2007 00:01:11 +0200 | From | "J.A. Magallón" <> | Subject | Re: Inlining can be _very_bad... |
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On Thu, 29 Mar 2007 19:52:54 +0200, Adrian Bunk <bunk@stusta.de> wrote:
> On Thu, Mar 29, 2007 at 01:18:38AM +0200, J.A. Magallón wrote: > > Hi all... > > > > I post this here as it can be of direct interest for kernel development > > (as I recall many discussions about inlining yes or no...). > > > > Testing other problems, I finally got this this issue: the same short > > and stupid loop lasted from 3 to 5 times more if it was in main() than > > if it was in an out-of-line function. The same (bad thing) happens if > > the function is inlined. > >... > > It looks like is updating the stack on each iteration...This is -march=opteron > > code, the -march=pentium4 is similar. Same behaviour with gcc3 and gcc4. > > > > tst.c and Makefile attached. > > > > Nice, isn't it ? Please, probe where is my fault... > > The only fault is to post this issue here instead of the gcc Bugzilla. >
Sorry, my intention was just something like 'take a look at your reduction-like code, perhaps its sloooow', something like checksum funtions in tcp or raid that are inlined expecting to be faster and in fact they are slower...
> In your example the compiler should produce code not slower than with > the out-of-line version when inlining. If it doesn't the bug in the > compiler resulting in this should be fixed. >
That's what I expected, but... Going to gcc bugzilla...
-- J.A. Magallon <jamagallon()ono!com> \ Software is like sex: \ It's better when it's free Mandriva Linux release 2007.1 (Cooker) for i586 Linux 2.6.20-jam06 (gcc 4.1.2 20070302 (prerelease) (4.1.2-1mdv2007.1)) #2 SMP PREEMPT - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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