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[188.28.125.106]) by smtp.gmail.com with ESMTPSA id t21-20020a05640203d500b0043573c59ea0sm9758451edw.90.2022.06.28.12.00.24 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 28 Jun 2022 12:00:25 -0700 (PDT) From: Pavel Begunkov To: io-uring@vger.kernel.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org Cc: "David S . Miller" , Jakub Kicinski , Jonathan Lemon , Willem de Bruijn , Jens Axboe , kernel-team@fb.com, Pavel Begunkov Subject: [RFC net-next v3 28/29] io_uring: batch submission notif referencing Date: Tue, 28 Jun 2022 19:56:50 +0100 Message-Id: X-Mailer: git-send-email 2.36.1 In-Reply-To: References: MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: io-uring@vger.kernel.org Batch get notifier references and use ->msg_ubuf_ref to hand off one ref per sendzc request to the network layer. This ammortises the submission side net_zcopy_get() atomics. Note that we always keep at least one reference in the cache because we do only post send checks on whether ->msg_ubuf_ref was consumed or not. Signed-off-by: Pavel Begunkov --- fs/io_uring.c | 32 +++++++++++++++++++++++++++++--- 1 file changed, 29 insertions(+), 3 deletions(-) diff --git a/fs/io_uring.c b/fs/io_uring.c index 08c98a4d9bd2..78990a130b66 100644 --- a/fs/io_uring.c +++ b/fs/io_uring.c @@ -374,6 +374,7 @@ struct io_ev_fd { }; #define IO_NOTIF_MAX_SLOTS (1U << 10) +#define IO_NOTIF_REF_CACHE_NR 64 struct io_notif { struct ubuf_info uarg; @@ -384,6 +385,8 @@ struct io_notif { u64 tag; /* see struct io_notif_slot::seq */ u32 seq; + /* extra uarg->refcnt refs */ + int cached_refs; /* hook into ctx->notif_list and ctx->notif_list_locked */ struct list_head cache_node; @@ -2949,14 +2952,30 @@ static struct io_notif *io_alloc_notif(struct io_ring_ctx *ctx, notif->seq = slot->seq++; notif->tag = slot->tag; + notif->cached_refs = IO_NOTIF_REF_CACHE_NR; /* master ref owned by io_notif_slot, will be dropped on flush */ - refcount_set(¬if->uarg.refcnt, 1); + refcount_set(¬if->uarg.refcnt, IO_NOTIF_REF_CACHE_NR + 1); percpu_ref_get(&ctx->refs); notif->rsrc_node = ctx->rsrc_node; io_charge_rsrc_node(ctx); return notif; } +static inline void io_notif_consume_ref(struct io_notif *notif) + __must_hold(&ctx->uring_lock) +{ + notif->cached_refs--; + + /* + * Issue sends without looking at notif->cached_refs first, so we + * always have to have at least one ref cached + */ + if (unlikely(!notif->cached_refs)) { + refcount_add(IO_NOTIF_REF_CACHE_NR, ¬if->uarg.refcnt); + notif->cached_refs += IO_NOTIF_REF_CACHE_NR; + } +} + static inline struct io_notif *io_get_notif(struct io_ring_ctx *ctx, struct io_notif_slot *slot) { @@ -2979,13 +2998,15 @@ static void io_notif_slot_flush(struct io_notif_slot *slot) __must_hold(&ctx->uring_lock) { struct io_notif *notif = slot->notif; + int refs = notif->cached_refs + 1; slot->notif = NULL; + notif->cached_refs = 0; if (WARN_ON_ONCE(in_interrupt())) return; - /* drop slot's master ref */ - if (refcount_dec_and_test(¬if->uarg.refcnt)) + /* drop all cached refs and the slot's master ref */ + if (refcount_sub_and_test(refs, ¬if->uarg.refcnt)) io_notif_complete(notif); } @@ -6653,6 +6674,7 @@ static int io_sendzc(struct io_kiocb *req, unsigned int issue_flags) msg.msg_controllen = 0; msg.msg_namelen = 0; msg.msg_managed_data = 1; + msg.msg_ubuf_ref = 1; if (req->msgzc.zc_flags & IORING_SENDZC_FIXED_BUF) { ret = __io_import_fixed(WRITE, &msg.msg_iter, req->imu, @@ -6686,6 +6708,10 @@ static int io_sendzc(struct io_kiocb *req, unsigned int issue_flags) msg.msg_ubuf = ¬if->uarg; ret = sock_sendmsg(sock, &msg); + /* check if the send consumed an additional ref */ + if (likely(!msg.msg_ubuf_ref)) + io_notif_consume_ref(notif); + if (likely(ret >= min_ret)) { unsigned zc_flags = req->msgzc.zc_flags;