From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-oi1-f173.google.com (mail-oi1-f173.google.com [209.85.167.173]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 69E39176253 for ; Thu, 30 May 2024 15:28:38 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.167.173 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1717082920; cv=none; b=kjBxxm+JdRBpTRq2M5h7GyT/JEm2uBWYTr1qRLalJpefzJgz3B6Y4PI9V2Vj1NKx6JICcCkHMzEe36N8ngWrAJEVXZCmeFRXunyQB6AGz2sNNX2uepfEBOfWufX5Kc8DjZ3KeIbH5s4XABUNN3LsTl6bznzqQFCY85rwmTvdqG0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1717082920; c=relaxed/simple; bh=I0yGKyybH2NDIn++3egAuNa/4hf42t0sOqm6hWTfrmo=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=oqj65/CCIILu7fnYgSRClArM2tFlLcUOWg+DQetEa64HgPJ7OLUYsUV4SP/6Wzmae66iH0ijHX7ofxnI4YGdnSCTxB9FrlG1w8Ls5qNGYED7VZjsM7ImhCGQHxBH4kIi6oIrNYeTCEafpfKISYnQiJoImsAOg4Bl6lf2aH5EeYc= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=kernel.dk; spf=pass smtp.mailfrom=kernel.dk; dkim=pass (2048-bit key) header.d=kernel-dk.20230601.gappssmtp.com header.i=@kernel-dk.20230601.gappssmtp.com header.b=Um9PW3OR; arc=none smtp.client-ip=209.85.167.173 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=kernel.dk Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=kernel.dk Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel-dk.20230601.gappssmtp.com header.i=@kernel-dk.20230601.gappssmtp.com header.b="Um9PW3OR" Received: by mail-oi1-f173.google.com with SMTP id 5614622812f47-3d1d411ffbbso32259b6e.3 for ; Thu, 30 May 2024 08:28:38 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel-dk.20230601.gappssmtp.com; s=20230601; t=1717082917; x=1717687717; darn=vger.kernel.org; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date :message-id:reply-to; bh=2TgpfwreZeaYJNBx6Jv2LBjJ5S4QzmxlRqOX0v4pzc8=; b=Um9PW3ORomNaGpfDKBGOPooKrrpNg/6t0aTZo3pK+dCZgN1qeWqmFSWVHPvz/VBGmT wpyVHAj47lGRMtxf8vG2xG9ajzSBAAuGfIs5InES21ID98uuDX8mP2zmaQEO16e5c6lI qnhQmW9CgEPuS2bG1/AOdQOjqX9lWaHGgy+tzFpfIVFiXBBdgF3rYa/ybz+VmABcL/D1 goD3TWaS+A2Z8s82OE4dy0bJKkNI0WZDoREFr76X/GcGBKZM0PZ/a0MrQppDxgLxMZZt 58ucZP2pmfhhEocrnedMg+/zTdp5di2Ms3PWPNQJpsivc8MJpwc2V2e6MtuZlTrCVult G6Yg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1717082917; x=1717687717; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=2TgpfwreZeaYJNBx6Jv2LBjJ5S4QzmxlRqOX0v4pzc8=; b=TZZ5UiIg6cfULzZ5xyMSmQwPgvm+vX2yZCJ9knyiohZtTDlAgdrJ+61XWyQshtNATx ODp0K2FF8tkVYqkBaJbq6Ejcx4UzXUlbU3ThUxCbpYeCC7SxHKjvSkA/pfxJAzNf2R9D ZDmB0xfAZ7GE4+i6/61g1YuQ0m4C30W8KCNDHhnjTrIUaGvTdJTyZoEU2IpPHqqer1yO SejvjR1bpxyd9m9NfHSHraxNa1/EvHpDisn3COz6b0tdOUagSfqI6lIHlsTZP5QLivGU +/wmpGPgLiFUB6W10IuADBz81JjlBBuSopshUc63kXtkI52eEURx8Iecz7KQvDbSg7pz hlLA== X-Gm-Message-State: AOJu0YzEDTj/St9fCoez3YfDzIoJDULi5AV+WgrEx1LbjAm7Xl/QgJ1m x2y7dHUEPRL9oPk/37B0+W7fwby29kOg+fkd+MR57jjfHoFBNovUPMJIPpe+yXP+BrPXN6VyxY8 W X-Google-Smtp-Source: AGHT+IE+GpXa5K1gLsVGH9sEsMXgHbL7bZ5bCiwb97FrrEZf/91NNqsNEbbIR3VElXbEVWLt1RTExQ== X-Received: by 2002:a05:6808:1903:b0:3d1:df5a:2e01 with SMTP id 5614622812f47-3d1df5a3ac4mr1658954b6e.5.1717082917067; Thu, 30 May 2024 08:28:37 -0700 (PDT) Received: from localhost.localdomain ([96.43.243.2]) by smtp.gmail.com with ESMTPSA id 5614622812f47-3d1b3682381sm2008136b6e.2.2024.05.30.08.28.35 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 30 May 2024 08:28:35 -0700 (PDT) From: Jens Axboe To: io-uring@vger.kernel.org Cc: Jens Axboe Subject: [PATCH 3/7] io_uring/msg_ring: avoid double indirection task_work for data messages Date: Thu, 30 May 2024 09:23:40 -0600 Message-ID: <20240530152822.535791-5-axboe@kernel.dk> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20240530152822.535791-2-axboe@kernel.dk> References: <20240530152822.535791-2-axboe@kernel.dk> Precedence: bulk X-Mailing-List: io-uring@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit If IORING_SETUP_DEFER_TASKRUN is set, then we can't post CQEs remotely to the target ring. Instead, task_work is queued for the target ring, which is used to post the CQE. To make matters worse, once the target CQE has been posted, task_work is then queued with the originator to fill the completion. This obviously adds a bunch of overhead and latency. Instead of relying on generic kernel task_work for this, fill an overflow entry on the target ring and flag it as such that the target ring will flush it. This avoids both the task_work for posting the CQE, and it means that the originator CQE can be filled inline as well. In local testing, this reduces the latency on the sender side by 5-6x. Signed-off-by: Jens Axboe --- io_uring/msg_ring.c | 87 ++++++++++++++++++++++++++++----------------- 1 file changed, 55 insertions(+), 32 deletions(-) diff --git a/io_uring/msg_ring.c b/io_uring/msg_ring.c index 15e7bda77d0d..bdb935ef7aa2 100644 --- a/io_uring/msg_ring.c +++ b/io_uring/msg_ring.c @@ -87,38 +87,61 @@ static int io_msg_exec_remote(struct io_kiocb *req, task_work_func_t func) return IOU_ISSUE_SKIP_COMPLETE; } -static void io_msg_tw_complete(struct callback_head *head) +static struct io_overflow_cqe *io_alloc_overflow(struct io_ring_ctx *target_ctx) { - struct io_msg *msg = container_of(head, struct io_msg, tw); - struct io_kiocb *req = cmd_to_io_kiocb(msg); - struct io_ring_ctx *target_ctx = req->file->private_data; - int ret = 0; - - if (current->flags & PF_EXITING) { - ret = -EOWNERDEAD; - } else { - u32 flags = 0; - - if (msg->flags & IORING_MSG_RING_FLAGS_PASS) - flags = msg->cqe_flags; - - /* - * If the target ring is using IOPOLL mode, then we need to be - * holding the uring_lock for posting completions. Other ring - * types rely on the regular completion locking, which is - * handled while posting. - */ - if (target_ctx->flags & IORING_SETUP_IOPOLL) - mutex_lock(&target_ctx->uring_lock); - if (!io_post_aux_cqe(target_ctx, msg->user_data, msg->len, flags)) - ret = -EOVERFLOW; - if (target_ctx->flags & IORING_SETUP_IOPOLL) - mutex_unlock(&target_ctx->uring_lock); + bool is_cqe32 = target_ctx->flags & IORING_SETUP_CQE32; + size_t cqe_size = sizeof(struct io_overflow_cqe); + struct io_overflow_cqe *ocqe; + + if (is_cqe32) + cqe_size += sizeof(struct io_uring_cqe); + + ocqe = kmalloc(cqe_size, GFP_ATOMIC | __GFP_ACCOUNT); + if (!ocqe) + return NULL; + + if (is_cqe32) + ocqe->cqe.big_cqe[0] = ocqe->cqe.big_cqe[1] = 0; + + return ocqe; +} + +/* + * Entered with the target uring_lock held, and will drop it before + * returning. Adds a previously allocated ocqe to the overflow list on + * the target, and marks it appropriately for flushing. + */ +static void io_msg_add_overflow(struct io_msg *msg, + struct io_ring_ctx *target_ctx, + struct io_overflow_cqe *ocqe, int ret, + u32 flags) + __releases(&target_ctx->completion_lock) +{ + if (list_empty(&target_ctx->cq_overflow_list)) { + set_bit(IO_CHECK_CQ_OVERFLOW_BIT, &target_ctx->check_cq); + atomic_or(IORING_SQ_TASKRUN, &target_ctx->rings->sq_flags); } - if (ret < 0) - req_set_fail(req); - io_req_queue_tw_complete(req, ret); + ocqe->cqe.user_data = msg->user_data; + ocqe->cqe.res = ret; + ocqe->cqe.flags = flags; + list_add_tail(&ocqe->list, &target_ctx->cq_overflow_list); + spin_unlock(&target_ctx->completion_lock); + wake_up_state(target_ctx->submitter_task, TASK_INTERRUPTIBLE); +} + +static int io_msg_fill_remote(struct io_msg *msg, unsigned int issue_flags, + struct io_ring_ctx *target_ctx, u32 flags) +{ + struct io_overflow_cqe *ocqe; + + ocqe = io_alloc_overflow(target_ctx); + if (!ocqe) + return -ENOMEM; + + spin_lock(&target_ctx->completion_lock); + io_msg_add_overflow(msg, target_ctx, ocqe, msg->len, flags); + return 0; } static int io_msg_ring_data(struct io_kiocb *req, unsigned int issue_flags) @@ -135,12 +158,12 @@ static int io_msg_ring_data(struct io_kiocb *req, unsigned int issue_flags) if (target_ctx->flags & IORING_SETUP_R_DISABLED) return -EBADFD; - if (io_msg_need_remote(target_ctx)) - return io_msg_exec_remote(req, io_msg_tw_complete); - if (msg->flags & IORING_MSG_RING_FLAGS_PASS) flags = msg->cqe_flags; + if (io_msg_need_remote(target_ctx)) + return io_msg_fill_remote(msg, issue_flags, target_ctx, flags); + ret = -EOVERFLOW; if (target_ctx->flags & IORING_SETUP_IOPOLL) { if (unlikely(io_double_lock_ctx(target_ctx, issue_flags))) -- 2.43.0