Messages in this thread | | | Date | Fri, 9 Jan 2009 19:59:22 +0100 | From | "Richard Guenther" <> | Subject | Re: [patch] measurements, numbers about CONFIG_OPTIMIZE_INLINING=y impact |
| |
On Fri, Jan 9, 2009 at 7:19 PM, Andi Kleen <andi@firstfloor.org> wrote: >> So we do have special issues. And exactly _because_ we have special issues >> we should also expect that some compiler defaults simply won't ever really >> be appropriate for us. > > I agree that the kernel needs quite different inlining heuristics > than let's say a template heavy C++ program. I guess that is > also where our trouble comes from -- gcc is more tuned for the > later. Perhaps because the C++ programmers are better at working > with the gcc developers? > > But it's also not inconceivable that gcc adds a -fkernel-inlining or > similar that changes the parameters if we ask nicely. I suppose > actually such a parameter would be useful for far more programs > than the kernel.
I think that the kernel is a perfect target to optimize default -Os behavior for (whereas template heavy C++ programs are a target to optimize -O2 for). And I think we did a good job in listening to kernel developers if once in time they tried to talk to us - GCC 4.3 should be good in compiling the kernel with default -Os settings. We, unfortunately, cannot retroactively fix old versions that kernel developers happen to like and still use.
Richard.
| |