| From | Arnd Bergmann <> | Date | Mon, 30 Dec 2019 13:07:43 +0100 | Subject | Re: [RFC PATCH v2 05/10] lib: vdso: inline do_hres() |
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On Mon, Dec 23, 2019 at 3:31 PM Christophe Leroy <christophe.leroy@c-s.fr> wrote: > > do_hres() is called from several places, so GCC doesn't inline > it at first. > > do_hres() takes a struct __kernel_timespec * parameter for > passing the result. In the 32 bits case, this parameter corresponds > to a local var in the caller. In order to provide a pointer > to this structure, the caller has to put it in its stack and > do_hres() has to write the result in the stack. This is suboptimal, > especially on RISC processor like powerpc. > > By making GCC inline the function, the struct __kernel_timespec > remains a local var using registers, avoiding the need to write and > read stack. > > The improvement is significant on powerpc. > > Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
Good idea, I can see how this ends up being an improvement for most of the callers.
Acked-by: Arnd Bergmann <arnd@arndb.de>
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