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io_uring: switch !DRAIN fast path when possible 

->drain_used is one way, which is not optimal if users use DRAIN but
very rarely. However, we can just clear it in io_drain_req() when all
drained before requests are gone. Also rename the flag to reflect the
change and be more clear about it.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/7f37a240857546a94df6348507edddacab150460.1623772051.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Pavel Begunkov 2021-06-15 16:47:56 +01:00 committed by Jens Axboe
parent 27f6b318de
commit 10c669040e
1 changed files with 8 additions and 6 deletions
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14
fs/io_uring.c
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@ -352,7 +352,7 @@ struct io_ring_ctx {
unsigned int eventfd_async: 1; unsigned int eventfd_async: 1;
unsigned int restricted: 1; unsigned int restricted: 1;
unsigned int off_timeout_used: 1; unsigned int off_timeout_used: 1;
unsigned int drain_used: 1; unsigned int drain_active: 1;
} ____cacheline_aligned_in_smp; } ____cacheline_aligned_in_smp;
/* submission data */ /* submission data */
@ -1346,10 +1346,10 @@ static void io_flush_timeouts(struct io_ring_ctx *ctx)
static void io_commit_cqring(struct io_ring_ctx *ctx) static void io_commit_cqring(struct io_ring_ctx *ctx)
{ {
if (unlikely(ctx->off_timeout_used || ctx->drain_used)) { if (unlikely(ctx->off_timeout_used || ctx->drain_active)) {
if (ctx->off_timeout_used) if (ctx->off_timeout_used)
io_flush_timeouts(ctx); io_flush_timeouts(ctx);
if (ctx->drain_used) if (ctx->drain_active)
io_queue_deferred(ctx); io_queue_deferred(ctx);
} }
/* order cqe stores with ring update */ /* order cqe stores with ring update */
@ -6004,8 +6004,10 @@ static bool io_drain_req(struct io_kiocb *req)
/* Still need defer if there is pending req in defer list. */ /* Still need defer if there is pending req in defer list. */
if (likely(list_empty_careful(&ctx->defer_list) && if (likely(list_empty_careful(&ctx->defer_list) &&
!(req->flags & REQ_F_IO_DRAIN))) !(req->flags & REQ_F_IO_DRAIN))) {
ctx->drain_active = false;
return false; return false;
}
seq = io_get_sequence(req); seq = io_get_sequence(req);
/* Still a chance to pass the sequence check */ /* Still a chance to pass the sequence check */
@ -6446,7 +6448,7 @@ static void __io_queue_sqe(struct io_kiocb *req)
static inline void io_queue_sqe(struct io_kiocb *req) static inline void io_queue_sqe(struct io_kiocb *req)
{ {
if (unlikely(req->ctx->drain_used) && io_drain_req(req)) if (unlikely(req->ctx->drain_active) && io_drain_req(req))
return; return;
if (likely(!(req->flags & REQ_F_FORCE_ASYNC))) { if (likely(!(req->flags & REQ_F_FORCE_ASYNC))) {
@ -6572,7 +6574,7 @@ fail_req:
} }
if (unlikely(req->flags & REQ_F_IO_DRAIN)) { if (unlikely(req->flags & REQ_F_IO_DRAIN)) {
ctx->drain_used = true; ctx->drain_active = true;
/* /*
* Taking sequential execution of a link, draining both sides * Taking sequential execution of a link, draining both sides