[PATCH 8/8] io_uring: optimise req bulk allocation cache

Pavel Begunkov
2020-01-24T21:41:50Z

Traverse backward through @reqs in struct io_submit_state, so it's
possible to remove cur_req from it and easier to handle in general.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
---
fs/io_uring.c | 12 +++---------
1 file changed, 3 insertions(+), 9 deletions(-)

diff --git a/fs/io_uring.c b/fs/io_uring.c
index aed19cbe9893..a4b496815783 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -206,7 +206,6 @@ struct io_submit_state {
*/
void *reqs[IO_IOPOLL_BATCH];
unsigned int free_reqs;
- unsigned int cur_req;

/*
* File reference cache
@@ -839,9 +838,7 @@ static void io_init_submit_state(struct io_ring_ctx *ctx)
struct io_submit_state *state = &ctx->submit_state;

state->mm = (ctx->flags & IORING_SETUP_SQPOLL) ? NULL : ctx->sqo_mm;
-
state->free_reqs = 0;
- state->cur_req = 0;
}

static void io_clear_submit_state(struct io_ring_ctx *ctx)
@@ -849,8 +846,7 @@ static void io_clear_submit_state(struct io_ring_ctx *ctx)
struct io_submit_state *state = &ctx->submit_state;

if (state->free_reqs)
- kmem_cache_free_bulk(req_cachep, state->free_reqs,
- &state->reqs[state->cur_req]);
+ kmem_cache_free_bulk(req_cachep, state->free_reqs, state->reqs);
}

static inline bool __req_need_defer(struct io_kiocb *req)
@@ -1167,12 +1163,10 @@ static struct io_kiocb *io_get_req(struct io_ring_ctx *ctx)
ret = 1;
}
state->free_reqs = ret - 1;
- state->cur_req = 1;
- req = state->reqs[0];
+ req = state->reqs[ret - 1];
} else {
- req = state->reqs[state->cur_req];
state->free_reqs--;
- state->cur_req++;
+ req = state->reqs[state->free_reqs];
}

got_it:
--
2.24.0