From 01950a349ec254f28bf9ad06e74a166521d213e1 Mon Sep 17 00:00:00 2001 From: Eric Biggers Date: Tue, 16 Jan 2018 22:25:12 -0800 Subject: fs/buffer.c: fold init_buffer() into init_page_buffers() Since commit e76004093db1 ("fs/buffer.c: remove unnecessary init operation after allocating buffer_head"), there are no callers of init_buffer() outside of init_page_buffers(). So just fold it into init_page_buffers(). Signed-off-by: Eric Biggers Signed-off-by: Al Viro --- include/linux/buffer_head.h | 1 - 1 file changed, 1 deletion(-) (limited to 'include/linux/buffer_head.h') diff --git a/include/linux/buffer_head.h b/include/linux/buffer_head.h index 8b1bf8d3d4a2..58a82f58e44e 100644 --- a/include/linux/buffer_head.h +++ b/include/linux/buffer_head.h @@ -151,7 +151,6 @@ void buffer_check_dirty_writeback(struct page *page, void mark_buffer_dirty(struct buffer_head *bh); void mark_buffer_write_io_error(struct buffer_head *bh); -void init_buffer(struct buffer_head *, bh_end_io_t *, void *); void touch_buffer(struct buffer_head *bh); void set_bh_page(struct buffer_head *bh, struct page *page, unsigned long offset); -- cgit v1.2.3 From 60f91826ca62bcf85d6d5fc90941337282787671 Mon Sep 17 00:00:00 2001 From: Kemi Wang Date: Tue, 24 Oct 2017 09:16:42 +0800 Subject: buffer: Avoid setting buffer bits that are already set It's expensive to set buffer flags that are already set, because that causes a costly cache line transition. A common case is setting the "verified" flag during ext4 writes. This patch checks for the flag being set first. With the AIM7/creat-clo benchmark testing on a 48G ramdisk based-on ext4 file system, we see 3.3%(15431->15936) improvement of aim7.jobs-per-min on a 2-sockets broadwell platform. What the benchmark does is: it forks 3000 processes, and each process do the following: a) open a new file b) close the file c) delete the file until loop=100*1000 times. The original patch is contributed by Andi Kleen. Signed-off-by: Andi Kleen Tested-by: Kemi Wang Signed-off-by: Kemi Wang Signed-off-by: Jens Axboe --- include/linux/buffer_head.h | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) (limited to 'include/linux/buffer_head.h') diff --git a/include/linux/buffer_head.h b/include/linux/buffer_head.h index 8b1bf8d3d4a2..06797ef10fd9 100644 --- a/include/linux/buffer_head.h +++ b/include/linux/buffer_head.h @@ -81,11 +81,14 @@ struct buffer_head { /* * macro tricks to expand the set_buffer_foo(), clear_buffer_foo() * and buffer_foo() functions. + * To avoid reset buffer flags that are already set, because that causes + * a costly cache line transition, check the flag first. */ #define BUFFER_FNS(bit, name) \ static __always_inline void set_buffer_##name(struct buffer_head *bh) \ { \ - set_bit(BH_##bit, &(bh)->b_state); \ + if (!test_bit(BH_##bit, &(bh)->b_state)) \ + set_bit(BH_##bit, &(bh)->b_state); \ } \ static __always_inline void clear_buffer_##name(struct buffer_head *bh) \ { \ -- cgit v1.2.3