From: Denis Kirjanov <kda@linux-powerpc.org>
To: Christophe Leroy <christophe.leroy@c-s.fr>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>,
Paul Mackerras <paulus@samba.org>,
Michael Ellerman <mpe@ellerman.id.au>,
Scott Wood <oss@buserror.net>,
linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v5 21/23] powerpc: Simplify test in __dma_sync()
Date: Thu, 4 Feb 2016 14:37:32 +0300 [thread overview]
Message-ID: <CAOJe8K2qmRARai6okSXtvpkt2JOfJCrqwUOinDAyo2Qoypd7uw@mail.gmail.com> (raw)
In-Reply-To: <42d5343703a9e67b5a2d94c8877bc0098448f71b.1454538980.git.christophe.leroy@c-s.fr>
On 2/4/16, Christophe Leroy <christophe.leroy@c-s.fr> wrote:
> This simplification helps the compiler. We now have only one test
> instead of two, so it reduces the number of branches.
>
> Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
> ---
> v2: new
> v3: no change
> v4: no change
> v5: no change
>
> arch/powerpc/mm/dma-noncoherent.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/arch/powerpc/mm/dma-noncoherent.c
> b/arch/powerpc/mm/dma-noncoherent.c
> index 169aba4..2dc74e5 100644
> --- a/arch/powerpc/mm/dma-noncoherent.c
> +++ b/arch/powerpc/mm/dma-noncoherent.c
> @@ -327,7 +327,7 @@ void __dma_sync(void *vaddr, size_t size, int direction)
> * invalidate only when cache-line aligned otherwise there is
> * the potential for discarding uncommitted data from the cache
> */
> - if ((start & (L1_CACHE_BYTES - 1)) || (size & (L1_CACHE_BYTES - 1)))
> + if ((start | end) & (L1_CACHE_BYTES - 1))
> flush_dcache_range(start, end);
> else
> invalidate_dcache_range(start, end);
The previous version of address cache-line aligned check reads perfectly fine.
What's the benefit of this micro optimization?
> --
> 2.1.0
>
> _______________________________________________
> Linuxppc-dev mailing list
> Linuxppc-dev@lists.ozlabs.org
> https://lists.ozlabs.org/listinfo/linuxppc-dev
next prev parent reply other threads:[~2016-02-04 11:56 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-02-03 22:53 [PATCH v5 00/23] powerpc/8xx: Use large pages for RAM and IMMR and other improvments Christophe Leroy
2016-02-03 22:53 ` [PATCH v5 01/23] powerpc/8xx: Save r3 all the time in DTLB miss handler Christophe Leroy
2016-02-03 22:53 ` [PATCH v5 02/23] powerpc/8xx: Map linear kernel RAM with 8M pages Christophe Leroy
2016-02-03 22:53 ` [PATCH v5 03/23] powerpc: Update documentation for noltlbs kernel parameter Christophe Leroy
2016-02-03 22:53 ` [PATCH v5 04/23] powerpc/8xx: move setup_initial_memory_limit() into 8xx_mmu.c Christophe Leroy
2016-02-03 22:53 ` [PATCH v5 05/23] powerpc32: Fix pte_offset_kernel() to return NULL for bad pages Christophe Leroy
2016-02-03 22:54 ` [PATCH v5 06/23] powerpc32: refactor x_mapped_by_bats() and x_mapped_by_tlbcam() together Christophe Leroy
2016-02-07 9:42 ` kbuild test robot
2016-02-03 22:54 ` [PATCH v5 07/23] powerpc/8xx: Fix vaddr for IMMR early remap Christophe Leroy
2016-02-03 22:54 ` [PATCH v5 08/23] powerpc/8xx: Map IMMR area with 512k page at a fixed address Christophe Leroy
2016-02-04 9:58 ` kbuild test robot
2016-02-03 22:54 ` [PATCH v5 09/23] powerpc/8xx: CONFIG_PIN_TLB unneeded for CONFIG_PPC_EARLY_DEBUG_CPM Christophe Leroy
2016-02-03 22:54 ` [PATCH v5 10/23] powerpc/8xx: map more RAM at startup when needed Christophe Leroy
2016-02-03 22:54 ` [PATCH v5 11/23] powerpc32: Remove useless/wrong MMU:setio progress message Christophe Leroy
2016-02-03 22:54 ` [PATCH v5 12/23] powerpc32: remove ioremap_base Christophe Leroy
2016-02-03 22:54 ` [PATCH v5 13/23] powerpc/8xx: Add missing SPRN defines into reg_8xx.h Christophe Leroy
2016-02-03 22:54 ` [PATCH v5 14/23] powerpc/8xx: Handle CPU6 ERRATA directly in mtspr() macro Christophe Leroy
2016-02-03 22:54 ` [PATCH v5 15/23] powerpc/8xx: remove special handling of CPU6 errata in set_dec() Christophe Leroy
2016-02-03 22:54 ` [PATCH v5 16/23] powerpc/8xx: rewrite set_context() in C Christophe Leroy
2016-02-03 22:54 ` [PATCH v5 17/23] powerpc/8xx: rewrite flush_instruction_cache() " Christophe Leroy
2016-02-03 22:54 ` [PATCH v5 18/23] powerpc: add inline functions for cache related instructions Christophe Leroy
2016-02-03 22:54 ` [PATCH v5 19/23] powerpc32: Remove clear_pages() and define clear_page() inline Christophe Leroy
2016-02-03 22:54 ` [PATCH v5 20/23] powerpc32: move xxxxx_dcache_range() functions inline Christophe Leroy
2016-02-03 22:54 ` [PATCH v5 21/23] powerpc: Simplify test in __dma_sync() Christophe Leroy
2016-02-04 11:37 ` Denis Kirjanov [this message]
2016-02-04 13:42 ` Christophe Leroy
2016-02-05 7:52 ` Denis Kirjanov
2016-02-05 7:56 ` Christophe Leroy
2016-02-03 22:54 ` [PATCH v5 22/23] powerpc32: small optimisation in flush_icache_range() Christophe Leroy
2016-02-03 22:54 ` [PATCH v5 23/23] powerpc32: Remove one insn in mulhdu Christophe Leroy
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