From patchwork Wed May 10 16:24:04 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jisheng Zhang X-Patchwork-Id: 13237072 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 bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 6649EC7EE22 for ; Wed, 10 May 2023 16:35:24 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:MIME-Version:References:In-Reply-To: Message-Id:Date:Subject:Cc:To:From:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=31vsxACMuencD5yY7UCmJ8vsXj/ajd5iJORDVlybpAw=; b=szpfGdqfmhFExR /lIpReRXAqOLXUYcSFan289eJl5Xjk7O0YQEbm/F9hezywmpsRyqPJdF6SX23uM+pQauLmDjqsQsB ox6WudikiYaWi8hwiYT8t7N5Abg5VuBRfvV5TD+hlwtuHcky9u3Rcr+9Q94K5pAmAbwklYjt503Np CYelXWGDmZ66CDnMQVQ39ep6hiaWzkK8rTChdyLaRg6BOj8Fhx8zX0mL4MVHIx9um31Bf/8zsb1Gi fvqOFZ5cAf1R7YCW4u/qO+Ma3WcG5WSrirkzEwVOwKqi3JMX1LeGjZ9Vr/7FDNj/MEPiQVy0QQeDv gxM8oPaLBUQu8FC9nJxw==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.96 #2 (Red Hat Linux)) id 1pwmmc-006aAA-38; Wed, 10 May 2023 16:35:18 +0000 Received: from dfw.source.kernel.org ([2604:1380:4641:c500::1]) by bombadil.infradead.org with esmtps (Exim 4.96 #2 (Red Hat Linux)) id 1pwmma-006a9U-1D for linux-riscv@lists.infradead.org; Wed, 10 May 2023 16:35:17 +0000 Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id DBB37649EF; Wed, 10 May 2023 16:35:15 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 4BEBAC4339C; Wed, 10 May 2023 16:35:13 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1683736515; bh=D/zx5C3wzjM0zZXbvIgMONVy5BqICz3TUA896+jQLlk=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=pM5PoYrty7yCH0RwPEETSGMTPtIBfqrDnxC1Of4QRrUvRYpcqhfo6CnKstuBdrJ1p Y8cTCUfcyPT9HCkODQhlW0ldspb1r8HMngbvPk58T/mxUVoWPYO0S8YT67WaBZmkkS 0guf3w7XP62n7Ufw6skcC1kTsgNS41PBKc3ftTIiOzKTnQIUvBMw98EWCV5UsjLA28 6w71JHcobAAmgW+ISjtdcEJaao3XBzY1Aov9TpeRhc+o6IRxbfwVCAXdnvBBH/xOYT JabESi0GONWMCoSl4Pw7TmgOCBO1uEBG3nscObwQzvG6izQ9zkRZEu5L++sWiusIiK gcuU64Yx8J6dw== From: Jisheng Zhang To: Sebastian Andrzej Siewior , Thomas Gleixner , Schaffner Tobias , Paul Walmsley , Palmer Dabbelt , Albert Ou , Arnd Bergmann Cc: linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org Subject: [PATCH RT 1/3] asm-generic/preempt: also check preempt_lazy_count for should_resched() etc. Date: Thu, 11 May 2023 00:24:04 +0800 Message-Id: <20230510162406.1955-2-jszhang@kernel.org> X-Mailer: git-send-email 2.40.0 In-Reply-To: <20230510162406.1955-1-jszhang@kernel.org> References: <20230510162406.1955-1-jszhang@kernel.org> MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20230510_093516_456340_3F9906D1 X-CRM114-Status: GOOD ( 12.29 ) X-BeenThere: linux-riscv@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-riscv" Errors-To: linux-riscv-bounces+linux-riscv=archiver.kernel.org@lists.infradead.org lazy preempt count is great mechanism to help ordinary SCHED_OTHER tasks' throughput Under PREEMPT_RT. But current implementation relies on each arch-specific code to check the preempt_lazy_count in should_resched() and __preempt_count_dec_and_test(), if the arch, e.g riscv use the asm-generic preempt implementation, it losts the great lazy preempt mechanism. Signed-off-by: Jisheng Zhang --- include/asm-generic/preempt.h | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) diff --git a/include/asm-generic/preempt.h b/include/asm-generic/preempt.h index b4d43a4af5f7..b583e7c38ccf 100644 --- a/include/asm-generic/preempt.h +++ b/include/asm-generic/preempt.h @@ -59,6 +59,11 @@ static __always_inline void __preempt_count_sub(int val) *preempt_count_ptr() -= val; } +#ifdef CONFIG_PREEMPT_LAZY +#define preempt_lazy_count() (current_thread_info()->preempt_lazy_count) +#else +#define preempt_lazy_count() (0) +#endif static __always_inline bool __preempt_count_dec_and_test(void) { /* @@ -66,7 +71,7 @@ static __always_inline bool __preempt_count_dec_and_test(void) * operations; we cannot use PREEMPT_NEED_RESCHED because it might get * lost. */ - return !--*preempt_count_ptr() && tif_need_resched(); + return !--*preempt_count_ptr() && !preempt_lazy_count() && tif_need_resched(); } /* @@ -75,6 +80,7 @@ static __always_inline bool __preempt_count_dec_and_test(void) static __always_inline bool should_resched(int preempt_offset) { return unlikely(preempt_count() == preempt_offset && + !preempt_lazy_count() && tif_need_resched()); }