Messages in this thread | | | From | Alexander Duyck <> | Subject | [PATCH v3 0/8] Improve performance of VM translation on x86_64 | Date | Mon, 05 Nov 2012 11:03:25 -0800 |
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This patch series is meant to address several issues I encountered with VM translations on x86_64. In my testing I found that swiotlb was incurring up to a 5% processing overhead due to calls to __phys_addr. To address that I have updated swiotlb to use physical addresses instead of virtual addresses to reduce the need to call __phys_addr. However those patches didn't address the other callers. With these patches applied I am able to achieve an additional 1% to 2% performance gain on top of the changes to swiotlb.
The first 2 patches are the performance optimizations that result in the 1% to 2% increase in overall performance. The remaining patches are various cleanups for a number of spots where __pa or virt_to_phys was being called and was not needed or __pa_symbol could have been used.
It doesn't seem like the v2 patch set was accepted so I am submitting an updated v3 set that is rebased off of linux-next with a few additional improvements to the existing patches. Specifically the first patch now also updates __virt_addr_valid so that it is almost identical in layout to __phys_addr. Also I found one additional spot in init_64.c that could use __pa_symbol instead of virt_to_page calls so I updated the first __pa_symbol patch for the x86 init calls.
With this patch set applied I am noticing a 1-2% improvement in performance in my routing tests. Without my earlier swiotlb changes applied it was getting as high as 6-7% because that code originally relied heavily on virt_to_phys.
The overall effect on size varies depending on what kernel options are enabled. I have notices that almost all of the network device drivers have dropped in size by around 100 bytes. I suspect this is due to the fact that the virt_to_page call in dma_map_single is now less expensive. However the default build for x86_64 increases the vmlinux size by 3.5K with this change applied.
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Alexander Duyck (8): x86/lguest: Use __pa_symbol instead of __pa on C visible symbols x86/acpi: Use __pa_symbol instead of __pa on C visible symbols x86/xen: Use __pa_symbol instead of __pa on C visible symbols x86/ftrace: Use __pa_symbol instead of __pa on C visible symbols x86: Use __pa_symbol instead of __pa on C visible symbols x86: Drop 4 unnecessary calls to __pa_symbol x86: Make it so that __pa_symbol can only process kernel symbols on x86_64 x86: Improve __phys_addr performance by making use of carry flags and inlining
arch/x86/include/asm/page.h | 3 +- arch/x86/include/asm/page_32.h | 1 + arch/x86/include/asm/page_64_types.h | 20 +++++++++++- arch/x86/kernel/acpi/sleep.c | 2 + arch/x86/kernel/cpu/intel.c | 2 + arch/x86/kernel/ftrace.c | 4 +- arch/x86/kernel/head32.c | 4 +- arch/x86/kernel/head64.c | 4 +- arch/x86/kernel/setup.c | 16 +++++----- arch/x86/kernel/x8664_ksyms_64.c | 3 ++ arch/x86/lguest/boot.c | 3 +- arch/x86/mm/init_64.c | 18 +++++------ arch/x86/mm/pageattr.c | 8 ++--- arch/x86/mm/physaddr.c | 55 +++++++++++++++++++++++++--------- arch/x86/platform/efi/efi.c | 4 +- arch/x86/realmode/init.c | 8 ++--- arch/x86/xen/mmu.c | 21 +++++++------ 17 files changed, 111 insertions(+), 65 deletions(-)
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