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authorPavel Begunkov <asml.silence@gmail.com>2024-03-18 22:00:32 +0000
committerJens Axboe <axboe@kernel.dk>2024-04-15 08:10:24 -0600
commit902ce82c2aa130bea5e3feca2d4ae62781865da7 (patch)
treeb1dc57d30ccaa7605ad5d675ce8e7a6c9756e7f8 /io_uring
parente5c12945be5016d681ff305ea7306fef5902219d (diff)
io_uring: get rid of intermediate aux cqe caches
io_post_aux_cqe(), which is used for multishot requests, delays completions by putting CQEs into a temporary array for the purpose completion lock/flush batching. DEFER_TASKRUN doesn't need any locking, so for it we can put completions directly into the CQ and defer post completion handling with a flag. That leaves !DEFER_TASKRUN, which is not that interesting / hot for multishot requests, so have conditional locking with deferred flush for them. Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> Tested-by: Ming Lei <ming.lei@redhat.com> Link: https://lore.kernel.org/r/b1d05a81fd27aaa2a07f9860af13059e7ad7a890.1710799188.git.asml.silence@gmail.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'io_uring')
-rw-r--r--io_uring/io_uring.c62
-rw-r--r--io_uring/io_uring.h2
2 files changed, 14 insertions, 50 deletions
diff --git a/io_uring/io_uring.c b/io_uring/io_uring.c
index 9ae5e7db7c6a..77e26b037fdd 100644
--- a/io_uring/io_uring.c
+++ b/io_uring/io_uring.c
@@ -630,6 +630,12 @@ static inline void __io_cq_lock(struct io_ring_ctx *ctx)
spin_lock(&ctx->completion_lock);
}
+static inline void __io_cq_unlock(struct io_ring_ctx *ctx)
+{
+ if (!ctx->lockless_cq)
+ spin_unlock(&ctx->completion_lock);
+}
+
static inline void io_cq_lock(struct io_ring_ctx *ctx)
__acquires(ctx->completion_lock)
{
@@ -882,31 +888,6 @@ static bool io_fill_cqe_aux(struct io_ring_ctx *ctx, u64 user_data, s32 res,
return false;
}
-static void __io_flush_post_cqes(struct io_ring_ctx *ctx)
- __must_hold(&ctx->uring_lock)
-{
- struct io_submit_state *state = &ctx->submit_state;
- unsigned int i;
-
- lockdep_assert_held(&ctx->uring_lock);
- for (i = 0; i < state->cqes_count; i++) {
- struct io_uring_cqe *cqe = &ctx->completion_cqes[i];
-
- if (!io_fill_cqe_aux(ctx, cqe->user_data, cqe->res, cqe->flags)) {
- if (ctx->lockless_cq) {
- spin_lock(&ctx->completion_lock);
- io_cqring_event_overflow(ctx, cqe->user_data,
- cqe->res, cqe->flags, 0, 0);
- spin_unlock(&ctx->completion_lock);
- } else {
- io_cqring_event_overflow(ctx, cqe->user_data,
- cqe->res, cqe->flags, 0, 0);
- }
- }
- }
- state->cqes_count = 0;
-}
-
bool io_post_aux_cqe(struct io_ring_ctx *ctx, u64 user_data, s32 res, u32 cflags)
{
bool filled;
@@ -927,31 +908,16 @@ bool io_post_aux_cqe(struct io_ring_ctx *ctx, u64 user_data, s32 res, u32 cflags
bool io_req_post_cqe(struct io_kiocb *req, s32 res, u32 cflags)
{
struct io_ring_ctx *ctx = req->ctx;
- u64 user_data = req->cqe.user_data;
- struct io_uring_cqe *cqe;
+ bool posted;
lockdep_assert(!io_wq_current_is_worker());
lockdep_assert_held(&ctx->uring_lock);
- if (ctx->submit_state.cqes_count == ARRAY_SIZE(ctx->completion_cqes)) {
- __io_cq_lock(ctx);
- __io_flush_post_cqes(ctx);
- /* no need to flush - flush is deferred */
- __io_cq_unlock_post(ctx);
- }
-
- /* For defered completions this is not as strict as it is otherwise,
- * however it's main job is to prevent unbounded posted completions,
- * and in that it works just as well.
- */
- if (test_bit(IO_CHECK_CQ_OVERFLOW_BIT, &ctx->check_cq))
- return false;
-
- cqe = &ctx->completion_cqes[ctx->submit_state.cqes_count++];
- cqe->user_data = user_data;
- cqe->res = res;
- cqe->flags = cflags;
- return true;
+ __io_cq_lock(ctx);
+ posted = io_fill_cqe_aux(ctx, req->cqe.user_data, res, cflags);
+ ctx->submit_state.cq_flush = true;
+ __io_cq_unlock_post(ctx);
+ return posted;
}
static void __io_req_complete_post(struct io_kiocb *req, unsigned issue_flags)
@@ -1545,9 +1511,6 @@ void __io_submit_flush_completions(struct io_ring_ctx *ctx)
struct io_wq_work_node *node;
__io_cq_lock(ctx);
- /* must come first to preserve CQE ordering in failure cases */
- if (state->cqes_count)
- __io_flush_post_cqes(ctx);
__wq_list_for_each(node, &state->compl_reqs) {
struct io_kiocb *req = container_of(node, struct io_kiocb,
comp_list);
@@ -1569,6 +1532,7 @@ void __io_submit_flush_completions(struct io_ring_ctx *ctx)
io_free_batch_list(ctx, state->compl_reqs.first);
INIT_WQ_LIST(&state->compl_reqs);
}
+ ctx->submit_state.cq_flush = false;
}
static unsigned io_cqring_events(struct io_ring_ctx *ctx)
diff --git a/io_uring/io_uring.h b/io_uring/io_uring.h
index 460290e1bdec..5119265a11c2 100644
--- a/io_uring/io_uring.h
+++ b/io_uring/io_uring.h
@@ -156,7 +156,7 @@ static inline void io_req_task_work_add(struct io_kiocb *req)
static inline void io_submit_flush_completions(struct io_ring_ctx *ctx)
{
if (!wq_list_empty(&ctx->submit_state.compl_reqs) ||
- ctx->submit_state.cqes_count)
+ ctx->submit_state.cq_flush)
__io_submit_flush_completions(ctx);
}