percpu: align percpu readmostly subsection to cacheline

Currently percpu readmostly subsection may share cachelines with other
percpu subsections which may result in unnecessary cacheline bounce
and performance degradation.

This patch adds @cacheline parameter to PERCPU() and PERCPU_VADDR()
linker macros, makes each arch linker scripts specify its cacheline
size and use it to align percpu subsections.

This is based on Shaohua's x86 only patch.

Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Shaohua Li <shaohua.li@intel.com>

1 files changed, 1 insertions, 1 deletions

diff --git a/arch/powerpc/kernel/vmlinux.lds.S b/arch/powerpc/kernel/vmlinux.lds.S
index 8a0deefac08d..b9150f07d266 100644
--- a/arch/powerpc/kernel/vmlinux.lds.S
+++ b/arch/powerpc/kernel/vmlinux.lds.S
@@ -160,7 +160,7 @@ SECTIONS
                 INIT_RAM_FS
         }
 
-        PERCPU(PAGE_SIZE)
+        PERCPU(L1_CACHE_BYTES, PAGE_SIZE)
 
         . = ALIGN(8);
         .machine.desc : AT(ADDR(.machine.desc) - LOAD_OFFSET) {