Re: Performance of function calls of SH?(Fw: [RFC][selinux] Tuning SELinux permission check

[Yuichi N. <yn...@hi...>]

On Mon, 10 Sep 2007 13:58:47 +0900
Paul Mundt  wrote:
> On Mon, Sep 10, 2007 at 01:35:14PM +0900, Yuichi Nakamura wrote:
> > > 3) Result for SH
> > >                 Base   SELinux  Overhead(%)
> > > Simple read     2.6781 3.6538  36.43(before 141.5)
> > > Simple write    2.0781 3.321   59.80(before 155.9)
> > In other archs, the effect of inlining was not so big,
> > but in SH it was big.
> > 
> > I could not find the reason.
> > Does anyone know why?
> > 
> > Are function calls on SH heavy?
> > Or gcc optimization does not work well?(I used gcc 3.4.5)
> > 
> I suspect you're mostly being bitten by your compiler version, it would
> be nice to see the numbers without the manual inlining with a more
> up-to-date compiler (4.1.x, 4.2.x, etc.).
> 
> > 1) Result for x86(Pentium 4 2.6Ghz), kernel 2.6.22
> > 2) Result for ARM(Intel XScale (PXA270 416MHz)), kernel 2.6.17
> > 3) Result for SH(SH4, SH7751R), kernel 2.6.22
> 
> What versions of the compiler did you have for x86 and ARM?
Thanks for reply and advice.
For arm, it is 3.4.4, for x86, 4.1.2.

> It's probably worth trying to do the manual inling for those old
> compilers (especially as there don't seem to be any regressions for any
> of the other platforms -- though you didn't list before and after code
> size), though I would be surprised if it's still problematic in current
> compilers. If you don't notice an improvement in more recent compilers,
> you may want to roll together a simple testcase and shove it in to the
> GCC bugzilla.
I would like to try newer gcc.

-- 
Yuichi Nakamura
Hitachi Software Engineering Co., Ltd.
Japan SELinux Users Group(JSELUG): http://www.selinux.gr.jp/
SELinux Policy Editor: http://seedit.sourceforge.net/