Re: [patch 2/3] mutex subsystem: fastpath inlining

From: Ingo Molnar
Date: Wed Dec 28 2005 - 02:42:43 EST



* Nicolas Pitre <nico@xxxxxxx> wrote:

> > * Nicolas Pitre <nico@xxxxxxx> wrote:
> >
> > > Some architectures, notably ARM for instance, might benefit from
> > > inlining the mutex fast paths. [...]
> >
> > what is the effect on text size? Could you post the before- and
> > after-patch vmlinux 'size kernel/test.o' output in the nondebug case,
> > with Arjan's latest 'convert a couple of semaphore users to mutexes'
> > patch applied? [make sure you've got enough of those users compiled in,
> > so that the inlining cost is truly measured. Perhaps also do
> > before/after 'size' output of a few affected .o files, without mixing
> > kernel/mutex.o into it, like vmlinux does.]
>
> Theory should be convincing enough. [...]

please provide actual measurements (just a simple pre-patch and
post-patch 'size' output of vmlinux is enough), so that we can see the
inlining cost. Note that x86 went to a non-inlined fastpath _despite_
having a compact CISC semaphore fastpath.

Ingo
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