MIPS: Optimize pgd_init and pmd_init (f59a2d22) · Commits · 戴 / test

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

+10 −10

Original line number	Diff line number	Diff line
		@@ -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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