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| author | Pavel Begunkov <asml.silence@gmail.com> | 2021-09-24 22:00:01 +0100 |
|---|---|---|
| committer | Jens Axboe <axboe@kernel.dk> | 2021-10-19 05:49:54 -0600 |
| commit | 6962980947e2b967ab26bfd34004b6b573597513 (patch) | |
| tree | d370fc40537317537080719f9eb1cb18b47391e4 /fs/io_uring.c | |
| parent | d9f9d2842c9156470b3f1d3dafe5684a3c036366 (diff) | |
| download | lwn-6962980947e2b967ab26bfd34004b6b573597513.tar.gz lwn-6962980947e2b967ab26bfd34004b6b573597513.zip | |
io_uring: restructure submit sqes to_submit checks
Put an explicit check for number of requests to submit. First,
we can turn while into do-while and it generates better code, and second
that if can be cheaper, e.g. by using CPU flags after sub in
io_sqring_entries().
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/5926baadd20c28feab7a5e1725fedf32e4553ff7.1632516769.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'fs/io_uring.c')
| -rw-r--r-- | fs/io_uring.c | 9 |
1 files changed, 6 insertions, 3 deletions
diff --git a/fs/io_uring.c b/fs/io_uring.c index bbb2a262c272..b8f60cf36156 100644 --- a/fs/io_uring.c +++ b/fs/io_uring.c @@ -7225,16 +7225,19 @@ static const struct io_uring_sqe *io_get_sqe(struct io_ring_ctx *ctx) static int io_submit_sqes(struct io_ring_ctx *ctx, unsigned int nr) __must_hold(&ctx->uring_lock) { + unsigned int entries = io_sqring_entries(ctx); int submitted = 0; + if (!entries) + return 0; /* make sure SQ entry isn't read before tail */ - nr = min3(nr, ctx->sq_entries, io_sqring_entries(ctx)); + nr = min3(nr, ctx->sq_entries, entries); if (!percpu_ref_tryget_many(&ctx->refs, nr)) return -EAGAIN; io_get_task_refs(nr); io_submit_state_start(&ctx->submit_state, nr); - while (submitted < nr) { + do { const struct io_uring_sqe *sqe; struct io_kiocb *req; @@ -7253,7 +7256,7 @@ static int io_submit_sqes(struct io_ring_ctx *ctx, unsigned int nr) submitted++; if (io_submit_sqe(ctx, req, sqe)) break; - } + } while (submitted < nr); if (unlikely(submitted != nr)) { int ref_used = (submitted == -EAGAIN) ? 0 : submitted; |