From: Wu Fengguang Remove 'fastcall' directive for readahead_cache_hit(). It leads to unfavorable performance in the following micro benchmark on i386 with CONFIG_REGPARM=n: Command: time cp cold /dev/null Summary: user sys cpu total no-fastcall 1.24 24.88 90.9 28.57 fastcall 1.16 25.69 91.5 29.23 Details: without fastcall: cp cold /dev/null 1.27s user 24.63s system 91% cpu 28.348 total cp cold /dev/null 1.17s user 25.09s system 91% cpu 28.653 total cp cold /dev/null 1.24s user 24.75s system 91% cpu 28.448 total cp cold /dev/null 1.20s user 25.04s system 91% cpu 28.614 total cp cold /dev/null 1.31s user 24.67s system 91% cpu 28.499 total cp cold /dev/null 1.30s user 24.87s system 91% cpu 28.530 total cp cold /dev/null 1.26s user 24.84s system 91% cpu 28.542 total cp cold /dev/null 1.16s user 25.15s system 90% cpu 28.925 total with fastcall: cp cold /dev/null 1.16s user 26.39s system 91% cpu 30.061 total cp cold /dev/null 1.25s user 26.53s system 91% cpu 30.378 total cp cold /dev/null 1.10s user 25.32s system 92% cpu 28.679 total cp cold /dev/null 1.15s user 25.20s system 91% cpu 28.747 total cp cold /dev/null 1.19s user 25.38s system 92% cpu 28.841 total cp cold /dev/null 1.11s user 25.75s system 92% cpu 29.126 total cp cold /dev/null 1.17s user 25.49s system 91% cpu 29.042 total cp cold /dev/null 1.17s user 25.49s system 92% cpu 28.970 total Signed-off-by: Wu Fengguang Signed-off-by: Andrew Morton --- include/linux/mm.h | 2 +- mm/readahead.c | 2 +- 2 files changed, 2 insertions(+), 2 deletions(-) diff -puN include/linux/mm.h~readahead-call-scheme-no-fastcall-for-readahead_cache_hit include/linux/mm.h --- a/include/linux/mm.h~readahead-call-scheme-no-fastcall-for-readahead_cache_hit +++ a/include/linux/mm.h @@ -1033,7 +1033,7 @@ page_cache_readahead_adaptive(struct add struct file_ra_state *ra, struct file *filp, struct page *prev_page, struct page *page, pgoff_t first_index, pgoff_t index, pgoff_t last_index); -void fastcall readahead_cache_hit(struct file_ra_state *ra, struct page *page); +void readahead_cache_hit(struct file_ra_state *ra, struct page *page); #ifdef CONFIG_ADAPTIVE_READAHEAD extern int readahead_ratio; diff -puN mm/readahead.c~readahead-call-scheme-no-fastcall-for-readahead_cache_hit mm/readahead.c --- a/mm/readahead.c~readahead-call-scheme-no-fastcall-for-readahead_cache_hit +++ a/mm/readahead.c @@ -1828,7 +1828,7 @@ readit: * readahead_cache_hit() is the feedback route of the adaptive read-ahead * logic. It must be called on every access on the read-ahead pages. */ -void fastcall readahead_cache_hit(struct file_ra_state *ra, struct page *page) +void readahead_cache_hit(struct file_ra_state *ra, struct page *page) { if (PageActive(page) || PageReferenced(page)) return; _