From patchwork Tue Aug 15 17:31:34 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Pavel Begunkov X-Patchwork-Id: 13354019 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 97E35C07E8F for ; Tue, 15 Aug 2023 17:34:04 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S238912AbjHORdh (ORCPT ); Tue, 15 Aug 2023 13:33:37 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:49688 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S238925AbjHORdW (ORCPT ); Tue, 15 Aug 2023 13:33:22 -0400 Received: from mail-lj1-x233.google.com (mail-lj1-x233.google.com [IPv6:2a00:1450:4864:20::233]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 31E791BD9 for ; Tue, 15 Aug 2023 10:33:20 -0700 (PDT) Received: by mail-lj1-x233.google.com with SMTP id 38308e7fff4ca-2b9db1de50cso85722541fa.3 for ; Tue, 15 Aug 2023 10:33:20 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20221208; t=1692120798; x=1692725598; 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=HnxxpondMX0aLczSzWm6JuyWlbpdwrNND3OM3Yt44kY=; b=bt4h+8NXY/G4i9d+eX7RH9cNGMrWlMWbbwyXKC0SZcreepSmsxZo66oAIosSkC2Uah zIaOxwDNUxLPk4RvfkfMMhvAhS33Qjh39RehSF61HJhG5Za4yXzki6TeElmrZTnFIuDJ vRGDGu7SqNb8z6peIjpX7eXjcsSKMxYEBYatfREnul+Ama5QKfVJsaHYN/90pgrRT+/+ Ctx1IrfoDcSglOJMuX+y5u5mRlRyBr+NzC/OCOGWn1IZuvl4H9XZRmSuXUo/bCZe0l60 UUXoVWlKeMFIInb1Hjhd6XMAXYQAQ2O7SWIcXmobeH2wGmK5zvprwm5nNz5czIjey160 7vBw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1692120798; x=1692725598; 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=HnxxpondMX0aLczSzWm6JuyWlbpdwrNND3OM3Yt44kY=; b=LJ+3Zh1uE1mqL/1rHLY2dhYsXER5DGWNPmSWjCxlrGrbfUnVWMwaic/pxYFQSbNrZj zk9nYaKkFf7Gekg6Q+C4l9qZiAIfi7RdGXV/nLPiwvyb9u7XaX3FCu6AyQhMP4Z4AJG6 chnE2oNOMo9CO0M5xwG2KJ2qLqfHfcpkQfT+ZM1x+6TtIdh77g1hYFV6XbzMb6pIlU4V mecbh6kkXpjE8aQZ/GJvrtIX9XVt2V/naBMSaTvXfGxmDAaqtrqCjaig7HnxEY2v4YXo XPwjzqorvXF73sZ013QWCpMGAz0AKuCtgs3RcK/ZpNBHr7K5JqbuEQo7iCpfDi+nejBK fbyQ== X-Gm-Message-State: AOJu0YwY0rZmuqGn6sECU6PsqVab2Eh3f1i19Hoi5gimiXVxv7loB1I2 fGZlQipsIZ/y4mXRDcxpsd4qNA0CA9w= X-Google-Smtp-Source: AGHT+IHHS8EoiYTjqNICdruoUOWF1Esbx++ib8DRNvKYQM9phZU8dwzYsYgfdiLwg4i5JNiYHGGb9w== X-Received: by 2002:a2e:9b98:0:b0:2b9:5b06:b73c with SMTP id z24-20020a2e9b98000000b002b95b06b73cmr9053738lji.17.1692120798131; Tue, 15 Aug 2023 10:33:18 -0700 (PDT) Received: from 127.com ([2620:10d:c092:600::2:6d35]) by smtp.gmail.com with ESMTPSA id kk9-20020a170907766900b0099cc36c4681sm7269878ejc.157.2023.08.15.10.33.17 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 15 Aug 2023 10:33:17 -0700 (PDT) From: Pavel Begunkov To: io-uring@vger.kernel.org Cc: Jens Axboe , asml.silence@gmail.com Subject: [PATCH 05/16] io_uring: optimise extra io_get_cqe null check Date: Tue, 15 Aug 2023 18:31:34 +0100 Message-ID: X-Mailer: git-send-email 2.41.0 In-Reply-To: References: MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: io-uring@vger.kernel.org If the cached cqe check passes in io_get_cqe*() it already means that the cqe we return is valid and non-zero, however the compiler is unable to optimise null checks like in io_fill_cqe_req(). Do a bit of trickery, return success/fail boolean from io_get_cqe*() and store cqe in the cqe parameter. That makes it do the right thing, erasing the check together with the introduced indirection. Signed-off-by: Pavel Begunkov --- io_uring/io_uring.c | 7 +++---- io_uring/io_uring.h | 20 +++++++++----------- 2 files changed, 12 insertions(+), 15 deletions(-) diff --git a/io_uring/io_uring.c b/io_uring/io_uring.c index 623d41755714..e5378dc7aa19 100644 --- a/io_uring/io_uring.c +++ b/io_uring/io_uring.c @@ -683,10 +683,10 @@ static void __io_cqring_overflow_flush(struct io_ring_ctx *ctx) io_cq_lock(ctx); while (!list_empty(&ctx->cq_overflow_list)) { - struct io_uring_cqe *cqe = io_get_cqe_overflow(ctx, true); + struct io_uring_cqe *cqe; struct io_overflow_cqe *ocqe; - if (!cqe) + if (!io_get_cqe_overflow(ctx, &cqe, true)) break; ocqe = list_first_entry(&ctx->cq_overflow_list, struct io_overflow_cqe, list); @@ -862,8 +862,7 @@ static bool io_fill_cqe_aux(struct io_ring_ctx *ctx, u64 user_data, s32 res, * submission (by quite a lot). Increment the overflow count in * the ring. */ - cqe = io_get_cqe(ctx); - if (likely(cqe)) { + if (likely(io_get_cqe(ctx, &cqe))) { trace_io_uring_complete(ctx, NULL, user_data, res, cflags, 0, 0); WRITE_ONCE(cqe->user_data, user_data); diff --git a/io_uring/io_uring.h b/io_uring/io_uring.h index 9c80d20fe18f..2960e35b32a5 100644 --- a/io_uring/io_uring.h +++ b/io_uring/io_uring.h @@ -109,28 +109,27 @@ static inline void io_req_task_work_add(struct io_kiocb *req) #define io_for_each_link(pos, head) \ for (pos = (head); pos; pos = pos->link) -static inline struct io_uring_cqe *io_get_cqe_overflow(struct io_ring_ctx *ctx, - bool overflow) +static inline bool io_get_cqe_overflow(struct io_ring_ctx *ctx, + struct io_uring_cqe **ret, + bool overflow) { - struct io_uring_cqe *cqe; - io_lockdep_assert_cq_locked(ctx); if (unlikely(ctx->cqe_cached >= ctx->cqe_sentinel)) { if (unlikely(!io_cqe_cache_refill(ctx, overflow))) - return NULL; + return false; } - cqe = ctx->cqe_cached; + *ret = ctx->cqe_cached; ctx->cached_cq_tail++; ctx->cqe_cached++; if (ctx->flags & IORING_SETUP_CQE32) ctx->cqe_cached++; - return cqe; + return true; } -static inline struct io_uring_cqe *io_get_cqe(struct io_ring_ctx *ctx) +static inline bool io_get_cqe(struct io_ring_ctx *ctx, struct io_uring_cqe **ret) { - return io_get_cqe_overflow(ctx, false); + return io_get_cqe_overflow(ctx, ret, false); } static inline bool io_fill_cqe_req(struct io_ring_ctx *ctx, struct io_kiocb *req) @@ -142,8 +141,7 @@ static inline bool io_fill_cqe_req(struct io_ring_ctx *ctx, struct io_kiocb *req * submission (by quite a lot). Increment the overflow count in * the ring. */ - cqe = io_get_cqe(ctx); - if (unlikely(!cqe)) + if (unlikely(!io_get_cqe(ctx, &cqe))) return false; if (trace_io_uring_complete_enabled())