On Tue, 2015-09-22 at 18:51 +0200, Christophe Leroy wrote:
> flush/clean/invalidate _dcache_range() functions are all very
> similar and are quite short. They are mainly used in __dma_sync()
> perf_event locate them in the top 3 consumming functions during
> heavy ethernet activity
>
> They are good candidate for inlining, as __dma_sync() does
> almost nothing but calling them
>
> Signed-off-by: Christophe Leroy <christophe.le...@c-s.fr>
> ---
> New in v2
>
> arch/powerpc/include/asm/cacheflush.h | 55 +++++++++++++++++++++++++++--
> arch/powerpc/kernel/misc_32.S | 65
> -----------------------------------
> arch/powerpc/kernel/ppc_ksyms.c | 2 ++
> 3 files changed, 54 insertions(+), 68 deletions(-)
>
> diff --git a/arch/powerpc/include/asm/cacheflush.h
> b/arch/powerpc/include/asm/cacheflush.h
> index 6229e6b..6169604 100644
> --- a/arch/powerpc/include/asm/cacheflush.h
> +++ b/arch/powerpc/include/asm/cacheflush.h
> @@ -47,12 +47,61 @@ static inline void __flush_dcache_icache_phys(unsigned
> long physaddr)
> }
> #endif
>
> -extern void flush_dcache_range(unsigned long start, unsigned long stop);
> #ifdef CONFIG_PPC32
> -extern void clean_dcache_range(unsigned long start, unsigned long stop);
> -extern void invalidate_dcache_range(unsigned long start, unsigned long stop);
> +/*
> + * Write any modified data cache blocks out to memory and invalidate them.
> + * Does not invalidate the corresponding instruction cache blocks.
> + */
> +static inline void flush_dcache_range(unsigned long start, unsigned long
> stop)
> +{
> + void *addr = (void *)(start & ~(L1_CACHE_BYTES - 1));
> + unsigned int size = stop - (unsigned long)addr + (L1_CACHE_BYTES - 1);
> + unsigned int i;
> +
> + for (i = 0; i < size >> L1_CACHE_SHIFT; i++, addr += L1_CACHE_BYTES)
> + dcbf(addr);
> + if (i)
> + mb(); /* sync */
> +}
This feels optimized for the uncommon case when there is no invalidation.
I THINK it would be better to bail early and use do { .. } while(--i); instead.
Jocke
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