From: Pavel Begunkov <[email protected]>
To: [email protected]
Cc: Jens Axboe <[email protected]>
Subject: Re: [PATCH 1/2] io_uring/rsrc: keep one global dummy_ubuf
Date: Wed, 9 Aug 2023 16:05:09 +0100 [thread overview]
Message-ID: <[email protected]> (raw)
In-Reply-To: <95c9dea5180d066dc35a94d39f4ce5a3ecdfbf77.1691546329.git.asml.silence@gmail.com>
On 8/9/23 13:25, Pavel Begunkov wrote:
> We set empty registered buffers to dummy_ubuf as an optimisation.
> Currently, we allocate the dummy entry for each ring, whenever we can
> simply have one global instance.
And only now it started complaining about const-ness, I'll
resend it.
> Signed-off-by: Pavel Begunkov <[email protected]>
> ---
> io_uring/io_uring.c | 9 ---------
> io_uring/rsrc.c | 14 ++++++++++----
> 2 files changed, 10 insertions(+), 13 deletions(-)
>
> diff --git a/io_uring/io_uring.c b/io_uring/io_uring.c
> index fb70ae436db6..3c97401240c2 100644
> --- a/io_uring/io_uring.c
> +++ b/io_uring/io_uring.c
> @@ -307,13 +307,6 @@ static __cold struct io_ring_ctx *io_ring_ctx_alloc(struct io_uring_params *p)
> goto err;
> if (io_alloc_hash_table(&ctx->cancel_table_locked, hash_bits))
> goto err;
> -
> - ctx->dummy_ubuf = kzalloc(sizeof(*ctx->dummy_ubuf), GFP_KERNEL);
> - if (!ctx->dummy_ubuf)
> - goto err;
> - /* set invalid range, so io_import_fixed() fails meeting it */
> - ctx->dummy_ubuf->ubuf = -1UL;
> -
> if (percpu_ref_init(&ctx->refs, io_ring_ctx_ref_free,
> 0, GFP_KERNEL))
> goto err;
> @@ -352,7 +345,6 @@ static __cold struct io_ring_ctx *io_ring_ctx_alloc(struct io_uring_params *p)
> INIT_WQ_LIST(&ctx->submit_state.compl_reqs);
> return ctx;
> err:
> - kfree(ctx->dummy_ubuf);
> kfree(ctx->cancel_table.hbs);
> kfree(ctx->cancel_table_locked.hbs);
> kfree(ctx->io_bl);
> @@ -2905,7 +2897,6 @@ static __cold void io_ring_ctx_free(struct io_ring_ctx *ctx)
> io_wq_put_hash(ctx->hash_map);
> kfree(ctx->cancel_table.hbs);
> kfree(ctx->cancel_table_locked.hbs);
> - kfree(ctx->dummy_ubuf);
> kfree(ctx->io_bl);
> xa_destroy(&ctx->io_bl_xa);
> kfree(ctx);
> diff --git a/io_uring/rsrc.c b/io_uring/rsrc.c
> index 5e8fdd9b8ca6..92e2471283ba 100644
> --- a/io_uring/rsrc.c
> +++ b/io_uring/rsrc.c
> @@ -33,6 +33,12 @@ static int io_sqe_buffer_register(struct io_ring_ctx *ctx, struct iovec *iov,
> #define IORING_MAX_FIXED_FILES (1U << 20)
> #define IORING_MAX_REG_BUFFERS (1U << 14)
>
> +static const struct io_mapped_ubuf dummy_ubuf = {
> + /* set invalid range, so io_import_fixed() fails meeting it */
> + .ubuf = -1UL,
> + .ubuf_end = 0,
> +};
> +
> int __io_account_mem(struct user_struct *user, unsigned long nr_pages)
> {
> unsigned long page_limit, cur_pages, new_pages;
> @@ -132,7 +138,7 @@ static void io_buffer_unmap(struct io_ring_ctx *ctx, struct io_mapped_ubuf **slo
> struct io_mapped_ubuf *imu = *slot;
> unsigned int i;
>
> - if (imu != ctx->dummy_ubuf) {
> + if (imu != &dummy_ubuf) {
> for (i = 0; i < imu->nr_bvecs; i++)
> unpin_user_page(imu->bvec[i].bv_page);
> if (imu->acct_pages)
> @@ -459,14 +465,14 @@ static int __io_sqe_buffers_update(struct io_ring_ctx *ctx,
> break;
>
> i = array_index_nospec(up->offset + done, ctx->nr_user_bufs);
> - if (ctx->user_bufs[i] != ctx->dummy_ubuf) {
> + if (ctx->user_bufs[i] != &dummy_ubuf) {
> err = io_queue_rsrc_removal(ctx->buf_data, i,
> ctx->user_bufs[i]);
> if (unlikely(err)) {
> io_buffer_unmap(ctx, &imu);
> break;
> }
> - ctx->user_bufs[i] = ctx->dummy_ubuf;
> + ctx->user_bufs[i] = &dummy_ubuf;
> }
>
> ctx->user_bufs[i] = imu;
> @@ -1077,7 +1083,7 @@ static int io_sqe_buffer_register(struct io_ring_ctx *ctx, struct iovec *iov,
> int ret, nr_pages, i;
> struct folio *folio = NULL;
>
> - *pimu = ctx->dummy_ubuf;
> + *pimu = &dummy_ubuf;
> if (!iov->iov_base)
> return 0;
>
--
Pavel Begunkov
next prev parent reply other threads:[~2023-08-09 15:06 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-08-09 12:25 [PATCH 0/2] random for-next cleanups Pavel Begunkov
2023-08-09 12:25 ` [PATCH 1/2] io_uring/rsrc: keep one global dummy_ubuf Pavel Begunkov
2023-08-09 15:05 ` Pavel Begunkov [this message]
2023-08-09 12:25 ` [PATCH 2/2] io_uring: simplify io_run_task_work_sig return Pavel Begunkov
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