Commit fcade2ce authored by Jens Axboe's avatar Jens Axboe
Browse files

block: use singly linked list for bio cache 



Pointless to maintain a head/tail for the list, as we never need to
access the tail. Entries are always LIFO for cache hotness reasons.

Reviewed-by: default avatarChristoph Hellwig <hch@lst.de>
Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent 5581a5dd

block/bio.c

+8 −5
Original line number Diff line number Diff line
@@ -26,7 +26,7 @@ 
#include "blk-rq-qos.h"



struct bio_alloc_cache {

	struct bio_list		free_list;

	struct bio		*free_list;

	unsigned int		nr;

};
@@ -630,7 +630,8 @@ static void bio_alloc_cache_prune(struct bio_alloc_cache *cache, 
	unsigned int i = 0;

	struct bio *bio;



	while ((bio = bio_list_pop(&cache->free_list)) != NULL) {

	while ((bio = cache->free_list) != NULL) {

		cache->free_list = bio->bi_next;

		cache->nr--;

		bio_free(bio);

		if (++i == nr)
@@ -689,7 +690,8 @@ void bio_put(struct bio *bio) 


		bio_uninit(bio);

		cache = per_cpu_ptr(bio->bi_pool->cache, get_cpu());

		bio_list_add_head(&cache->free_list, bio);

		bio->bi_next = cache->free_list;

		cache->free_list = bio;

		if (++cache->nr > ALLOC_CACHE_MAX + ALLOC_CACHE_SLACK)

			bio_alloc_cache_prune(cache, ALLOC_CACHE_SLACK);

		put_cpu();
@@ -1704,8 +1706,9 @@ struct bio *bio_alloc_kiocb(struct kiocb *kiocb, unsigned short nr_vecs, 
		return bio_alloc_bioset(GFP_KERNEL, nr_vecs, bs);



	cache = per_cpu_ptr(bs->cache, get_cpu());

	bio = bio_list_pop(&cache->free_list);

	if (bio) {

	if (cache->free_list) {

		bio = cache->free_list;

		cache->free_list = bio->bi_next;

		cache->nr--;

		put_cpu();

		bio_init(bio, nr_vecs ? bio->bi_inline_vecs : NULL, nr_vecs);