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Re: 40% performance regression SPEC2006/leslie3d on gcc-4_2-branch
Daniel Berlin wrote:
>> 2. What is the effort required to backport the necessary infrastructure
>> from 4.3? I'm not looking for "a lot" or "is hard", but rather, "two
>> weeks" or "six months". What needs to be backported, and what are the
>> challenges?
>
> Including bug fixes, i'd guess 2 months to be conservative.
OK, thanks. That seems like a lot of effort; certainly more than I
could try to browbeat you into doing. :-)
> There are no real challenges other than applying the patches and doing
> a lot of testing, since most of these patches were written pretty
> early on during the 4.3 cycle.
Is there anyone brave enough to volunteer to try? If this were to turn
out to be substantially easier than Danny thinks, then it sounds like it
might be a good solution. However, there's no reason to expect that,
and I think two person-months is rather much.
Therefore, it sounds like the practical choices are revert the patch and
accept the bugs, or vice versa. Is there any reason to expect the bugs
to be particularly more prevalent in 4.2 than they were in 4.1?
--
Mark Mitchell
CodeSourcery
mark@codesourcery.com
(650) 331-3385 x713