On 11/05/2012 02:08 PM, Kirill A. Shutemov wrote: > On Mon, Nov 05, 2012 at 01:56:28PM -0800, Alexander Duyck wrote: >> On 11/05/2012 12:24 PM, Kirill A. Shutemov wrote: >>> On Mon, Nov 05, 2012 at 11:04:06AM -0800, Alexander Duyck wrote: >>>> 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. >>>> >>>> When building the kernel with the first two changes applied I saw build >>>> warnings about __START_KERNEL_map and PAGE_OFFSET constants not fitting in >>>> their type. In order to resolve the build warning I changed their type >>>> from >>>> UL to ULL. >>> What kind of warning messages did you see? >>> It's strange: sizeof(unsinged long) == sizeof(unsinged long long) on >>> x86_64 >> One of the warnings is included below: >> >> In file included from >> /usr/src/kernels/linux-next/arch/x86/include/asm/page_types.h:37, >> from >> /usr/src/kernels/linux-next/arch/x86/include/asm/pgtable_types.h:5, >> from >> /usr/src/kernels/linux-next/arch/x86/include/asm/boot.h:11, >> from arch/x86/realmode/rm/../../boot/boot.h:26, >> from arch/x86/realmode/rm/../../boot/regs.c:19, >> from arch/x86/realmode/rm/regs.c:1: >> /usr/src/kernels/linux-next/arch/x86/include/asm/page_64_types.h: In >> function '__phys_addr_nodebug': >> /usr/src/kernels/linux-next/arch/x86/include/asm/page_64_types.h:63: >> warning: integer constant is too large for 'unsigned long' type >> /usr/src/kernels/linux-next/arch/x86/include/asm/page_64_types.h:66: >> warning: integer constant is too large for 'unsigned long' type >> /usr/src/kernels/linux-next/arch/x86/include/asm/page_64_types.h:66: >> warning: integer constant is too large for 'unsigned long' type >> >> The warnings all seemed to originate from several different spots >> throughout the x86 tree. All of the warning messages include >> arch/x86/boot/boot.h:26 and then from there up the included from list is >> always the same. > Realmode code compiles with -m32. I guess it's just wrong that it tries to > include <asm/page_64_types.h>. >
I have been reviewing things and I think the problem is due to the fact that we have content in page_64_types.h that doesn't really belong there. I will add a patch that moves the virtual to physical address translation header contents over to page_64.h. That will keep it consistent with where it is in the 32 bit build (page_32.h) and avoids the build conflicts. Expect a v4 of the patches with this fixed in the next few hours. Thanks, Alex -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
