From e8de85ca32f572f5dee00733022d8a1ce87aed3d Mon Sep 17 00:00:00 2001 From: Christophe Leroy Date: Wed, 19 Apr 2017 14:56:24 +0200 Subject: [PATCH] powerpc/mm: Only call store_updates_sp() on stores in do_page_fault() Function store_updates_sp() checks whether the faulting instruction is a store updating r1. Therefore we can limit its calls to store exceptions. This patch is an improvement of commit a7a9dcd882a67 ("powerpc: Avoid taking a data miss on every userspace instruction miss") With the same microbenchmark app, run with 500 as argument, on an MPC885 we get: Before this patch: 152000 DTLB misses After this patch: 147000 DTLB misses Signed-off-by: Christophe Leroy Reviewed-by: Aneesh Kumar K.V Signed-off-by: Michael Ellerman --- arch/powerpc/mm/fault.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/arch/powerpc/mm/fault.c b/arch/powerpc/mm/fault.c index 3a7d580..67fefb5 100644 --- a/arch/powerpc/mm/fault.c +++ b/arch/powerpc/mm/fault.c @@ -287,7 +287,7 @@ int do_page_fault(struct pt_regs *regs, unsigned long address, * can result in fault, which will cause a deadlock when called with * mmap_sem held */ - if (!is_exec && user_mode(regs)) + if (is_write && user_mode(regs)) store_update_sp = store_updates_sp(regs); if (user_mode(regs)) -- 2.7.4