Messages in this thread | | | Date | Thu, 5 Jan 2006 11:02:55 -0600 | From | Matt Mackall <> | Subject | Re: [patch 00/2] improve .text size on gcc 4.0 and newer compilers |
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On Thu, Jan 05, 2006 at 01:19:12PM +0100, Arjan van de Ven wrote: > > > What would be nice to do is pack all the frequently used code together > > in close proximity. Would probably have much larger effects with > > userspace code, esp where we touch disk (which is more page-size > > granularity), but is probably worth doing with kernel code too (where > > AFAICS we'd only get cacheline granular). > > in the kernel we could make a .text.rare section for functions, which we > could annotate with __rare. > The other way around, __fastpath or whatever is a bad idea, everyone > will consider all of their own functions as such (just like inline ;)... > go-fast-stripes all the way :-(
Gah, we don't want to do this by hand in either direction. It's the inline nightmare all over again.
It'd be better to take a tool like oprofile and run it against some test suite to generate a usage map, then re-sort based on the map. Then ship a "standard" map in the stock tarball. Note that the map need only list the popular functions.
The ideal sampling tool can collect second order information: which functions are executed near each other as well as which are executed most frequently.
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