From f59a2d22a05272034e856b7a2dd7a3ab7864a2ae Mon Sep 17 00:00:00 2001
From: David Daney <ddaney@caviumnetworks.com>
Date: Thu, 16 Aug 2012 11:15:22 -0700
Subject: [PATCH] MIPS: Optimize pgd_init and pmd_init
On a dual issue processor GCC generates code that saves a couple of
clock cycles per loop if we rearrange things slightly. Checking for
p != end saves a SLTU per loop, moving the increment to the middle can
let it dual issue on multi-issue processors.
Signed-off-by: David Daney <ddaney@caviumnetworks.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/4249/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
---
arch/mips/mm/pgtable-64.c | 20 ++++++++++----------
1 file changed, 10 insertions(+), 10 deletions(-)
diff --git a/arch/mips/mm/pgtable-64.c b/arch/mips/mm/pgtable-64.c
index cda4e300eb0a8c..25407794edb4ff 100644
--- a/arch/mips/mm/pgtable-64.c
+++ b/arch/mips/mm/pgtable-64.c
@@ -26,17 +26,17 @@ void pgd_init(unsigned long page)
p = (unsigned long *) page;
end = p + PTRS_PER_PGD;
- while (p < end) {
+ do {
p[0] = entry;
p[1] = entry;
p[2] = entry;
p[3] = entry;
p[4] = entry;
- p[5] = entry;
- p[6] = entry;
- p[7] = entry;
p += 8;
- }
+ p[-3] = entry;
+ p[-2] = entry;
+ p[-1] = entry;
+ } while (p != end);
}
#ifndef __PAGETABLE_PMD_FOLDED
@@ -47,17 +47,17 @@ void pmd_init(unsigned long addr, unsigned long pagetable)
p = (unsigned long *) addr;
end = p + PTRS_PER_PMD;
- while (p < end) {
+ do {
p[0] = pagetable;
p[1] = pagetable;
p[2] = pagetable;
p[3] = pagetable;
p[4] = pagetable;
- p[5] = pagetable;
- p[6] = pagetable;
- p[7] = pagetable;
p += 8;
- }
+ p[-3] = pagetable;
+ p[-2] = pagetable;
+ p[-1] = pagetable;
+ } while (p != end);
}
#endif
--
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