From e269b085175acf03fc687a7416b9fd84aa9c6c23 Mon Sep 17 00:00:00 2001 From: Anton Blanchard Date: Mon, 9 Aug 2010 17:20:23 -0700 Subject: [PATCH] iommu: inline iommu_num_pages A profile of a network benchmark showed iommu_num_pages rather high up: 0.52% iommu_num_pages Looking at the profile, an integer divide is taking almost all of the time: % : c000000000376ea4 <.iommu_num_pages>: 1.93 : c000000000376ea4: fb e1 ff f8 std r31,-8(r1) 0.00 : c000000000376ea8: f8 21 ff c1 stdu r1,-64(r1) 0.00 : c000000000376eac: 7c 3f 0b 78 mr r31,r1 3.86 : c000000000376eb0: 38 84 ff ff addi r4,r4,-1 0.00 : c000000000376eb4: 38 05 ff ff addi r0,r5,-1 0.00 : c000000000376eb8: 7c 84 2a 14 add r4,r4,r5 46.95 : c000000000376ebc: 7c 00 18 38 and r0,r0,r3 45.66 : c000000000376ec0: 7c 84 02 14 add r4,r4,r0 0.00 : c000000000376ec4: 7c 64 2b 92 divdu r3,r4,r5 0.00 : c000000000376ec8: 38 3f 00 40 addi r1,r31,64 0.00 : c000000000376ecc: eb e1 ff f8 ld r31,-8(r1) 1.61 : c000000000376ed0: 4e 80 00 20 blr Since every caller of iommu_num_pages passes in a constant power of two we can inline this such that the divide is replaced by a shift. The entire function is only a few instructions once optimised, so it is a good candidate for inlining overall. Signed-off-by: Anton Blanchard Cc: Akinobu Mita Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/iommu-helper.h | 12 ++++++++++-- lib/iommu-helper.c | 9 --------- 2 files changed, 10 insertions(+), 11 deletions(-) diff --git a/include/linux/iommu-helper.h b/include/linux/iommu-helper.h index 64d1b638745d..86bdeffe43ad 100644 --- a/include/linux/iommu-helper.h +++ b/include/linux/iommu-helper.h @@ -1,6 +1,8 @@ #ifndef _LINUX_IOMMU_HELPER_H #define _LINUX_IOMMU_HELPER_H +#include + static inline unsigned long iommu_device_max_index(unsigned long size, unsigned long offset, u64 dma_mask) @@ -20,7 +22,13 @@ extern unsigned long iommu_area_alloc(unsigned long *map, unsigned long size, unsigned long boundary_size, unsigned long align_mask); -extern unsigned long iommu_num_pages(unsigned long addr, unsigned long len, - unsigned long io_page_size); +static inline unsigned long iommu_num_pages(unsigned long addr, + unsigned long len, + unsigned long io_page_size) +{ + unsigned long size = (addr & (io_page_size - 1)) + len; + + return DIV_ROUND_UP(size, io_page_size); +} #endif diff --git a/lib/iommu-helper.c b/lib/iommu-helper.c index c0251f4ad08b..da053313ee5c 100644 --- a/lib/iommu-helper.c +++ b/lib/iommu-helper.c @@ -38,12 +38,3 @@ unsigned long iommu_area_alloc(unsigned long *map, unsigned long size, return -1; } EXPORT_SYMBOL(iommu_area_alloc); - -unsigned long iommu_num_pages(unsigned long addr, unsigned long len, - unsigned long io_page_size) -{ - unsigned long size = (addr & (io_page_size - 1)) + len; - - return DIV_ROUND_UP(size, io_page_size); -} -EXPORT_SYMBOL(iommu_num_pages); -- GitLab