From: Pavel Begunkov <[email protected]>
To: Jens Axboe <[email protected]>,
[email protected], [email protected]
Subject: Re: [PATCH v4 2/2] io_uring: batch getting pcpu references
Date: Sat, 28 Dec 2019 14:15:54 +0300 [thread overview]
Message-ID: <[email protected]> (raw)
In-Reply-To: <1250dad37e9b73d39066a8b464f6d2cab26eef8a.1577528535.git.asml.silence@gmail.com>
On 28/12/2019 14:13, Pavel Begunkov wrote:
> percpu_ref_tryget() has its own overhead. Instead getting a reference
> for each request, grab a bunch once per io_submit_sqes().
>
> ~5% throughput boost for a "submit and wait 128 nops" benchmark.
>
> Signed-off-by: Pavel Begunkov <[email protected]>
> ---
> fs/io_uring.c | 26 +++++++++++++++++---------
> 1 file changed, 17 insertions(+), 9 deletions(-)
>
> diff --git a/fs/io_uring.c b/fs/io_uring.c
> index 7fc1158bf9a4..404946080e86 100644
> --- a/fs/io_uring.c
> +++ b/fs/io_uring.c
> @@ -1080,9 +1080,6 @@ static struct io_kiocb *io_get_req(struct io_ring_ctx *ctx,
> gfp_t gfp = GFP_KERNEL | __GFP_NOWARN;
> struct io_kiocb *req;
>
> - if (!percpu_ref_tryget(&ctx->refs))
> - return NULL;
> -
> if (!state) {
> req = kmem_cache_alloc(req_cachep, gfp);
> if (unlikely(!req))
> @@ -1141,6 +1138,14 @@ static void io_free_req_many(struct io_ring_ctx *ctx, void **reqs, int *nr)
> }
> }
>
> +static void __io_req_free_empty(struct io_kiocb *req)
If anybody have better naming (or a better approach at all), I'm all ears.
> +{
> + if (likely(!io_is_fallback_req(req)))
> + kmem_cache_free(req_cachep, req);
> + else
> + clear_bit_unlock(0, (unsigned long *) req->ctx->fallback_req);
> +}
> +
> static void __io_free_req(struct io_kiocb *req)
> {
> struct io_ring_ctx *ctx = req->ctx;
> @@ -1162,11 +1167,9 @@ static void __io_free_req(struct io_kiocb *req)
> wake_up(&ctx->inflight_wait);
> spin_unlock_irqrestore(&ctx->inflight_lock, flags);
> }
> - percpu_ref_put(&ctx->refs);
> - if (likely(!io_is_fallback_req(req)))
> - kmem_cache_free(req_cachep, req);
> - else
> - clear_bit_unlock(0, (unsigned long *) ctx->fallback_req);
> +
> + percpu_ref_put(&req->ctx->refs);
> + __io_req_free_empty(req);
> }
>
> static bool io_link_cancel_timeout(struct io_kiocb *req)
> @@ -4551,6 +4554,9 @@ static int io_submit_sqes(struct io_ring_ctx *ctx, unsigned int nr,
> return -EBUSY;
> }
>
> + if (!percpu_ref_tryget_many(&ctx->refs, nr))
> + return -EAGAIN;
> +
> if (nr > IO_PLUG_THRESHOLD) {
> io_submit_state_start(&state, nr);
> statep = &state;
> @@ -4567,7 +4573,7 @@ static int io_submit_sqes(struct io_ring_ctx *ctx, unsigned int nr,
> break;
> }
> if (!io_get_sqring(ctx, req, &sqe)) {
> - __io_free_req(req);
> + __io_req_free_empty(req);
> break;
> }
>
> @@ -4598,6 +4604,8 @@ static int io_submit_sqes(struct io_ring_ctx *ctx, unsigned int nr,
> break;
> }
>
> + if (submitted != nr)
> + percpu_ref_put_many(&ctx->refs, nr - submitted);
> if (link)
> io_queue_link_head(link);
> if (statep)
>
--
Pavel Begunkov
next prev parent reply other threads:[~2019-12-28 11:16 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-12-17 22:28 [PATCH 0/2] optimise ctx's refs grabbing in io_uring Pavel Begunkov
2019-12-17 22:28 ` [PATCH 1/2] pcpu_ref: add percpu_ref_tryget_many() Pavel Begunkov
2019-12-17 23:42 ` Jens Axboe
2019-12-18 16:26 ` Tejun Heo
2019-12-18 17:49 ` Dennis Zhou
2019-12-21 15:36 ` Pavel Begunkov
2019-12-17 22:28 ` [PATCH 2/2] io_uring: batch getting pcpu references Pavel Begunkov
2019-12-17 23:21 ` Jens Axboe
2019-12-17 23:31 ` Jens Axboe
2019-12-18 9:25 ` Pavel Begunkov
2019-12-18 9:23 ` Pavel Begunkov
2019-12-18 0:02 ` Jens Axboe
2019-12-18 10:41 ` Pavel Begunkov
2019-12-21 16:15 ` [PATCH v2 0/3] optimise ctx's refs grabbing in io_uring Pavel Begunkov
2019-12-21 16:15 ` [PATCH v2 1/3] pcpu_ref: add percpu_ref_tryget_many() Pavel Begunkov
2019-12-21 16:15 ` [PATCH v2 2/3] io_uring: batch getting pcpu references Pavel Begunkov
2019-12-21 16:15 ` [PATCH RFC v2 3/3] io_uring: batch get(ctx->ref) across submits Pavel Begunkov
2019-12-21 16:20 ` Pavel Begunkov
2019-12-21 16:38 ` Jens Axboe
2019-12-21 16:48 ` Pavel Begunkov
2019-12-21 17:01 ` Jens Axboe
2019-12-21 17:26 ` Pavel Begunkov
2019-12-21 20:12 ` [PATCH v3 0/2] optimise ctx's refs grabbing in io_uring Pavel Begunkov
2019-12-21 20:12 ` [PATCH v3 1/2] pcpu_ref: add percpu_ref_tryget_many() Pavel Begunkov
2019-12-21 20:12 ` [PATCH v3 2/2] io_uring: batch getting pcpu references Pavel Begunkov
2019-12-21 21:56 ` Pavel Begunkov
2019-12-28 11:13 ` [PATCH v4 0/2] optimise ctx's refs grabbing in io_uring Pavel Begunkov
2019-12-28 11:13 ` [PATCH v4 1/2] pcpu_ref: add percpu_ref_tryget_many() Pavel Begunkov
2019-12-28 11:13 ` [PATCH v4 2/2] io_uring: batch getting pcpu references Pavel Begunkov
2019-12-28 11:15 ` Pavel Begunkov [this message]
2019-12-28 17:03 ` Jens Axboe
2019-12-28 18:37 ` Pavel Begunkov
2019-12-30 3:33 ` Brian Gianforcaro
2019-12-30 18:45 ` Pavel Begunkov
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