From c957ef2c59e952803766ddc22e89981ab534606f Mon Sep 17 00:00:00 2001 From: Shaohua Li Date: Wed, 20 Oct 2010 11:07:02 +0800 Subject: [PATCH] percpu: Introduce a read-mostly percpu API Add a new readmostly percpu section and API. This can be used to avoid dirtying data lines which are generally not written to, which is especially important for data which may be accessed by processors other than the one for which the percpu area belongs to. [ hpa: moved it *after* the page-aligned section, for obvious reasons. ] Signed-off-by: Shaohua Li LKML-Reference: <1287544022.4571.7.camel@sli10-conroe.sh.intel.com> Cc: Eric Dumazet Signed-off-by: H. Peter Anvin --- include/asm-generic/vmlinux.lds.h | 4 ++++ include/linux/percpu-defs.h | 9 +++++++++ 2 files changed, 13 insertions(+) diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h index 8a92a170fb7d..d7e7b21511b1 100644 --- a/include/asm-generic/vmlinux.lds.h +++ b/include/asm-generic/vmlinux.lds.h @@ -677,7 +677,9 @@ - LOAD_OFFSET) { \ VMLINUX_SYMBOL(__per_cpu_start) = .; \ *(.data..percpu..first) \ + . = ALIGN(PAGE_SIZE); \ *(.data..percpu..page_aligned) \ + *(.data..percpu..readmostly) \ *(.data..percpu) \ *(.data..percpu..shared_aligned) \ VMLINUX_SYMBOL(__per_cpu_end) = .; \ @@ -703,6 +705,8 @@ VMLINUX_SYMBOL(__per_cpu_load) = .; \ VMLINUX_SYMBOL(__per_cpu_start) = .; \ *(.data..percpu..first) \ + . = ALIGN(PAGE_SIZE); \ + *(.data..percpu..readmostly) \ *(.data..percpu..page_aligned) \ *(.data..percpu) \ *(.data..percpu..shared_aligned) \ diff --git a/include/linux/percpu-defs.h b/include/linux/percpu-defs.h index ce2dc655cd1d..27ef6b190ea6 100644 --- a/include/linux/percpu-defs.h +++ b/include/linux/percpu-defs.h @@ -138,6 +138,15 @@ DEFINE_PER_CPU_SECTION(type, name, "..page_aligned") \ __aligned(PAGE_SIZE) +/* + * Declaration/definition used for per-CPU variables that must be read mostly. + */ +#define DECLARE_PER_CPU_READ_MOSTLY(type, name) \ + DECLARE_PER_CPU_SECTION(type, name, "..readmostly") + +#define DEFINE_PER_CPU_READ_MOSTLY(type, name) \ + DEFINE_PER_CPU_SECTION(type, name, "..readmostly") + /* * Intermodule exports for per-CPU variables. sparse forgets about * address space across EXPORT_SYMBOL(), change EXPORT_SYMBOL() to -- GitLab