![Alexander Duyck](/assets/img/avatar_default.png)
This patch is meant to improve overall system performance when making use of the __phys_addr call. To do this I have implemented several changes. First if CONFIG_DEBUG_VIRTUAL is not defined __phys_addr is made an inline, similar to how this is currently handled in 32 bit. However in order to do this it is required to export phys_base so that it is available if __phys_addr is used in kernel modules. The second change was to streamline the code by making use of the carry flag on an add operation instead of performing a compare on a 64 bit value. The advantage to this is that it allows us to significantly reduce the overall size of the call. On my Xeon E5 system the entire __phys_addr inline call consumes a little less than 32 bytes and 5 instructions. I also applied similar logic to the debug version of the function. My testing shows that the debug version of the function with this patch applied is slightly faster than the non-debug version without the patch. Finally I also applied the same logic changes to __virt_addr_valid since it used the same general code flow as __phys_addr and could achieve similar gains though these changes. Signed-off-by: Alexander Duyck <alexander.h.duyck@intel.com> Link: http://lkml.kernel.org/r/20121116215315.8521.46270.stgit@ahduyck-cp1.jf.intel.com Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
40 lines
857 B
C
40 lines
857 B
C
#ifndef _ASM_X86_PAGE_64_H
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#define _ASM_X86_PAGE_64_H
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#include <asm/page_64_types.h>
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#ifndef __ASSEMBLY__
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/* duplicated to the one in bootmem.h */
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extern unsigned long max_pfn;
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extern unsigned long phys_base;
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static inline unsigned long __phys_addr_nodebug(unsigned long x)
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{
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unsigned long y = x - __START_KERNEL_map;
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/* use the carry flag to determine if x was < __START_KERNEL_map */
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x = y + ((x > y) ? phys_base : (__START_KERNEL_map - PAGE_OFFSET));
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return x;
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}
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#ifdef CONFIG_DEBUG_VIRTUAL
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extern unsigned long __phys_addr(unsigned long);
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#else
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#define __phys_addr(x) __phys_addr_nodebug(x)
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#endif
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#define __phys_reloc_hide(x) (x)
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#ifdef CONFIG_FLATMEM
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#define pfn_valid(pfn) ((pfn) < max_pfn)
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#endif
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void clear_page(void *page);
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void copy_page(void *to, void *from);
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#endif /* !__ASSEMBLY__ */
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#endif /* _ASM_X86_PAGE_64_H */
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