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/alpha/kernel/vmlinux.lds.S b/arch/alpha/kernel/vmlinux.lds.S
index 003ef4c02585..173518f8c8bb 100644
--- a/arch/alpha/kernel/vmlinux.lds.S
+++ b/arch/alpha/kernel/vmlinux.lds.S
@@ -38,7 +38,7 @@ SECTIONS
         __init_begin = ALIGN(PAGE_SIZE);
         INIT_TEXT_SECTION(PAGE_SIZE)
         INIT_DATA_SECTION(16)
-        PERCPU(PAGE_SIZE)
+        PERCPU(64, PAGE_SIZE)
         /* Align to THREAD_SIZE rather than PAGE_SIZE here so any padding page
            needed for the THREAD_SIZE aligned init_task gets freed after init */
         . = ALIGN(THREAD_SIZE);