lkml.org 
[lkml]   [2015]   [Sep]   [22]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    From
    SubjectRe: [PATCH v2 20/25] powerpc32: Remove clear_pages() and define clear_page() inline
    Date
    Hi Christophe

    Really nice patchset!

    On Tue, 2015-09-22 at 18:51 +0200, Christophe Leroy wrote:
    > clear_pages() is never used, and PPC32 is the only architecture
    > (still) having this function. Neither PPC64 nor any other
    > architecture has it.
    >
    > This patch removes clear_page() and move clear_page() function
    > inline (same as PPC64) as it only is a few isns
    >
    > Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
    > ---
    > No change in v2
    >
    > arch/powerpc/include/asm/page_32.h | 17 ++++++++++++++---
    > arch/powerpc/kernel/misc_32.S | 16 ----------------
    > arch/powerpc/kernel/ppc_ksyms_32.c | 1 -
    > 3 files changed, 14 insertions(+), 20 deletions(-)
    >
    > diff --git a/arch/powerpc/include/asm/page_32.h b/arch/powerpc/include/asm/page_32.h
    > index 68d73b2..6a8e179 100644
    > --- a/arch/powerpc/include/asm/page_32.h
    > +++ b/arch/powerpc/include/asm/page_32.h
    > @@ -1,6 +1,8 @@
    > #ifndef _ASM_POWERPC_PAGE_32_H
    > #define _ASM_POWERPC_PAGE_32_H
    >
    > +#include <asm/cache.h>
    > +
    > #if defined(CONFIG_PHYSICAL_ALIGN) && (CONFIG_PHYSICAL_START != 0)
    > #if (CONFIG_PHYSICAL_START % CONFIG_PHYSICAL_ALIGN) != 0
    > #error "CONFIG_PHYSICAL_START must be a multiple of CONFIG_PHYSICAL_ALIGN"
    > @@ -36,9 +38,18 @@ typedef unsigned long long pte_basic_t;
    > typedef unsigned long pte_basic_t;
    > #endif
    >
    > -struct page;
    > -extern void clear_pages(void *page, int order);
    > -static inline void clear_page(void *page) { clear_pages(page, 0); }
    > +/*
    > + * Clear page using the dcbz instruction, which doesn't cause any
    > + * memory traffic (except to write out any cache lines which get
    > + * displaced). This only works on cacheable memory.
    > + */
    > +static inline void clear_page(void *addr)
    > +{
    > + unsigned int i;
    > +
    > + for (i = 0; i < PAGE_SIZE / L1_CACHE_BYTES; i++, addr += L1_CACHE_BYTES)
    > + dcbz(addr);
    > +}

    Does gcc manage to transform this into efficient asm?
    Otherwise you could help gcc by using do { .. } while(--i); instead.


    \
     
     \ /
      Last update: 2015-09-22 20:21    [W:2.636 / U:0.244 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site