[PATCH v3 6/6] io_uring: optimise req bulk allocation cache

From: Pavel Begunkov
Date: Fri Jan 31 2020 - 17:17:06 EST


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@xxxxxxxxx>
---
fs/io_uring.c | 11 +++--------
1 file changed, 3 insertions(+), 8 deletions(-)

diff --git a/fs/io_uring.c b/fs/io_uring.c
index 66742d5772fa..799e80e85027 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
@@ -850,7 +849,6 @@ static void io_init_submit_state(struct io_ring_ctx *ctx)
struct io_submit_state *state = &ctx->submit_state;

state->free_reqs = 0;
- state->cur_req = 0;
}

static void io_clear_submit_state(struct io_ring_ctx *ctx)
@@ -858,8 +856,7 @@ 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)
@@ -1204,12 +1201,10 @@ 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