From e57ef2ed97c1d078973298658a8096644a1e9e09 Mon Sep 17 00:00:00 2001 From: Thomas Gleixner Date: Thu, 15 Sep 2022 13:11:01 +0200 Subject: x86: Put hot per CPU variables into a struct The layout of per-cpu variables is at the mercy of the compiler. This can lead to random performance fluctuations from build to build. Create a structure to hold some of the hottest per-cpu variables, starting with current_task. Signed-off-by: Thomas Gleixner Signed-off-by: Peter Zijlstra (Intel) Link: https://lore.kernel.org/r/20220915111145.179707194@infradead.org --- arch/x86/include/asm/current.h | 19 ++++++++++++++++--- 1 file changed, 16 insertions(+), 3 deletions(-) (limited to 'arch/x86/include/asm') diff --git a/arch/x86/include/asm/current.h b/arch/x86/include/asm/current.h index 3e204e6140b5..63c42ac3cd86 100644 --- a/arch/x86/include/asm/current.h +++ b/arch/x86/include/asm/current.h @@ -3,16 +3,29 @@ #define _ASM_X86_CURRENT_H #include -#include #ifndef __ASSEMBLY__ + +#include +#include + struct task_struct; -DECLARE_PER_CPU(struct task_struct *, current_task); +struct pcpu_hot { + union { + struct { + struct task_struct *current_task; + }; + u8 pad[64]; + }; +}; +static_assert(sizeof(struct pcpu_hot) == 64); + +DECLARE_PER_CPU_ALIGNED(struct pcpu_hot, pcpu_hot); static __always_inline struct task_struct *get_current(void) { - return this_cpu_read_stable(current_task); + return this_cpu_read_stable(pcpu_hot.current_task); } #define current get_current() -- cgit v1.2.3