Re: -fPIC for core

[Sam S. <sd...@gn...>]

> * Vladimir Tzankov <igmnaxbi@tznvy.pbz> [2009-08-16 20:11:26 +0300]:
>
> On 8/14/09, Sam Steingold <sd...@gn...> wrote:
>> Bruno Haible wrote:
>>> It's possible. Last time I measured it, it caused a performance decrease
>>> of 17%,
>>> on x86. You have to know that position-independent code means that every
>>> access
>>> to a global variable needs special code so that the access goes through
>>> %eip.
>>
>> this pretty much kills the idea.
>> however, these 17% looks like a lot - if it were true, people should have
>> screamed about it it should have been fixed.
>
> It's somehow relevant.
> I observe that MT builds are 10-20% slower than single thread ones -
> mainly due to additional indirection when accessing globals.

is this cumulative with -fPIC?

i.e., is there any penalty from -fPIC in -DMULTITHREAD?

-- 
Sam Steingold (http://sds.podval.org/) on Ubuntu 9.04 (jaunty)
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