| Message ID | 20190227124013.4828-5-ming.lei@redhat.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | block: optimize for single-page bvec workloads | expand |
On Wed, Feb 27, 2019 at 08:40:13PM +0800, Ming Lei wrote: > mp_bvec_for_each_segment() is a bit big for the iteration, so introduce > a light-weight helper for iterating over pages, then 32bytes stack > space can be saved. The version in Jens' tree seems to add this helper, but no actual users..
On 2/28/19 7:13 AM, Christoph Hellwig wrote: > On Wed, Feb 27, 2019 at 08:40:13PM +0800, Ming Lei wrote: >> mp_bvec_for_each_segment() is a bit big for the iteration, so introduce >> a light-weight helper for iterating over pages, then 32bytes stack >> space can be saved. > > The version in Jens' tree seems to add this helper, but no actual > users.. io_uring uses it, which is based on the block branch. But hopefully that too can go away, if the iov/bio no-ref stuff is reviewed + merged...
diff --git a/block/bio.c b/block/bio.c index eae8b754801d..7917535123df 100644 --- a/block/bio.c +++ b/block/bio.c @@ -849,8 +849,7 @@ static int __bio_iov_bvec_add_pages(struct bio *bio, struct iov_iter *iter) size = bio_add_page(bio, bv->bv_page, len, bv->bv_offset + iter->iov_offset); if (size == len) { - struct bvec_iter_all iter_all; - struct bio_vec *tmp; + struct page *pg; int i; /* @@ -862,8 +861,8 @@ static int __bio_iov_bvec_add_pages(struct bio *bio, struct iov_iter *iter) * get rid of the get here and the need to call * bio_release_pages() at IO completion time. */ - mp_bvec_for_each_segment(tmp, bv, i, iter_all) - get_page(tmp->bv_page); + mp_bvec_for_each_page(pg, bv, i) + get_page(pg); iov_iter_advance(iter, size); return 0; } diff --git a/include/linux/bvec.h b/include/linux/bvec.h index 4376f683c08a..2c32e3e151a0 100644 --- a/include/linux/bvec.h +++ b/include/linux/bvec.h @@ -188,4 +188,9 @@ static inline void mp_bvec_last_segment(const struct bio_vec *bvec, } } +#define mp_bvec_for_each_page(pg, bv, i) \ + for (i = (bv)->bv_offset / PAGE_SIZE; \ + (i < (((bv)->bv_offset + (bv)->bv_len) / PAGE_SIZE)) && \ + (pg = bvec_nth_page((bv)->bv_page, i)); i += 1) + #endif /* __LINUX_BVEC_ITER_H */
mp_bvec_for_each_segment() is a bit big for the iteration, so introduce a light-weight helper for iterating over pages, then 32bytes stack space can be saved. Signed-off-by: Ming Lei <ming.lei@redhat.com> --- block/bio.c | 7 +++---- include/linux/bvec.h | 5 +++++ 2 files changed, 8 insertions(+), 4 deletions(-)