Re: [PATCH 1/2] ARM: implement support for read-mostly sections
On 5 December 2010 23:04, Russell King - ARM Linux li...@arm.linux.org.uk wrote: On Sun, Dec 05, 2010 at 10:18:27PM +, Catalin Marinas wrote: On 5 December 2010 11:43, Russell King - ARM Linux li...@arm.linux.org.uk wrote: diff --git a/arch/arm/kernel/vmlinux.lds.S b/arch/arm/kernel/vmlinux.lds.S index cead889..1581f6d 100644 --- a/arch/arm/kernel/vmlinux.lds.S +++ b/arch/arm/kernel/vmlinux.lds.S @@ -167,6 +167,7 @@ SECTIONS NOSAVE_DATA CACHELINE_ALIGNED_DATA(32) + READ_MOSTLY_DATA(32) Should we change the alignments to 64? When we have some way to tell vmlinux.lds.S what the cache line size is. I haven't tried but can we not use CONFIG_ARM_L1_CACHE_SHIFT? -- Catalin -- To unsubscribe from this list: send the line unsubscribe linux-omap in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
[PATCH 1/2] ARM: implement support for read-mostly sections
As our SMP implementation uses MESI protocols. Grouping together data which is mostly only read together means that we avoid unnecessary cache line bouncing when this code shares a cache line with other data. In other words, cache lines associated with read-mostly data are expected to spend most of their time in shared state. Signed-off-by: Russell King rmk+ker...@arm.linux.org.uk --- arch/arm/include/asm/cache.h |2 ++ arch/arm/kernel/vmlinux.lds.S |1 + 2 files changed, 3 insertions(+), 0 deletions(-) diff --git a/arch/arm/include/asm/cache.h b/arch/arm/include/asm/cache.h index 9d61220..75fe66b 100644 --- a/arch/arm/include/asm/cache.h +++ b/arch/arm/include/asm/cache.h @@ -23,4 +23,6 @@ #define ARCH_SLAB_MINALIGN 8 #endif +#define __read_mostly __attribute__((__section__(.data..read_mostly))) + #endif diff --git a/arch/arm/kernel/vmlinux.lds.S b/arch/arm/kernel/vmlinux.lds.S index cead889..1581f6d 100644 --- a/arch/arm/kernel/vmlinux.lds.S +++ b/arch/arm/kernel/vmlinux.lds.S @@ -167,6 +167,7 @@ SECTIONS NOSAVE_DATA CACHELINE_ALIGNED_DATA(32) + READ_MOSTLY_DATA(32) /* * The exception fixup table (might need resorting at runtime) -- 1.6.2.5 -- To unsubscribe from this list: send the line unsubscribe linux-omap in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: [PATCH 1/2] ARM: implement support for read-mostly sections
On 5 December 2010 11:43, Russell King - ARM Linux li...@arm.linux.org.uk wrote: As our SMP implementation uses MESI protocols. Grouping together data which is mostly only read together means that we avoid unnecessary cache line bouncing when this code shares a cache line with other data. In other words, cache lines associated with read-mostly data are expected to spend most of their time in shared state. Signed-off-by: Russell King rmk+ker...@arm.linux.org.uk --- arch/arm/include/asm/cache.h | 2 ++ arch/arm/kernel/vmlinux.lds.S | 1 + 2 files changed, 3 insertions(+), 0 deletions(-) diff --git a/arch/arm/include/asm/cache.h b/arch/arm/include/asm/cache.h index 9d61220..75fe66b 100644 --- a/arch/arm/include/asm/cache.h +++ b/arch/arm/include/asm/cache.h @@ -23,4 +23,6 @@ #define ARCH_SLAB_MINALIGN 8 #endif +#define __read_mostly __attribute__((__section__(.data..read_mostly))) + #endif diff --git a/arch/arm/kernel/vmlinux.lds.S b/arch/arm/kernel/vmlinux.lds.S index cead889..1581f6d 100644 --- a/arch/arm/kernel/vmlinux.lds.S +++ b/arch/arm/kernel/vmlinux.lds.S @@ -167,6 +167,7 @@ SECTIONS NOSAVE_DATA CACHELINE_ALIGNED_DATA(32) + READ_MOSTLY_DATA(32) Should we change the alignments to 64? -- Catalin -- To unsubscribe from this list: send the line unsubscribe linux-omap in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: [PATCH 1/2] ARM: implement support for read-mostly sections
On Sun, Dec 05, 2010 at 10:18:27PM +, Catalin Marinas wrote: On 5 December 2010 11:43, Russell King - ARM Linux li...@arm.linux.org.uk wrote: diff --git a/arch/arm/kernel/vmlinux.lds.S b/arch/arm/kernel/vmlinux.lds.S index cead889..1581f6d 100644 --- a/arch/arm/kernel/vmlinux.lds.S +++ b/arch/arm/kernel/vmlinux.lds.S @@ -167,6 +167,7 @@ SECTIONS NOSAVE_DATA CACHELINE_ALIGNED_DATA(32) + READ_MOSTLY_DATA(32) Should we change the alignments to 64? When we have some way to tell vmlinux.lds.S what the cache line size is. It should be a separate patch. -- To unsubscribe from this list: send the line unsubscribe linux-omap in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
