From mboxrd@z Thu Jan 1 00:00:00 1970 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 78911C54F4C for ; Tue, 28 Jul 2026 12:40:06 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:Cc:List-Subscribe: List-Help:List-Post:List-Archive:List-Unsubscribe:List-Id: Content-Transfer-Encoding:MIME-Version:References:In-Reply-To:Message-Id:Date :Subject:To:From:Reply-To:Content-Type:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=419KN+4kNCoqwT/bg3p1DwChGvlb6Rr5+FRaPL1OlUE=; b=mWYbUgpGZvbr5P u2eVmsW4ND3TAOQvawZamSZSMTjYvkrUadVNWjYkWL3MBD7pXUPOcOwLU+GZF1xYbcKKspWP+OXX5 eXwPSaZydyr67uO+yNO/38W7eK0HMlNKT9kmy9McSVueSVrtxJp3/BhpSyhkik2n83IrMmdU2uQ/T w2pM6lwNBR7JzMlxzFzoUF5R+gWIiPdVY5cfkJ2MbmOKj9qXGsrvXQYccc2D1zSAkDDGR5vxwbHT+ wNqDj9scmOL8c67twwkJd4+vMARjyhCXSriZw0RJvUXufHT+7aEhNTwrnWTOnAN6Zx7MXRSisixBg ZLQ/+zQNwqMT1r4LufnA==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.99.1 #2 (Red Hat Linux)) id 1woh68-00000005GQc-436i; Tue, 28 Jul 2026 12:39:52 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.99.1 #2 (Red Hat Linux)) id 1woh63-00000005GOY-2dqw for linux-arm-kernel@lists.infradead.org; Tue, 28 Jul 2026 12:39:48 +0000 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id C8DD6175D; Tue, 28 Jul 2026 05:39:41 -0700 (PDT) Received: from lakrids.cambridge.arm.com (usa-sjc-imap-foss1.foss.arm.com [10.121.207.14]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id 115513F86F; Tue, 28 Jul 2026 05:39:43 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=arm.com; s=foss; t=1785242385; bh=pWV6z+z312qnQhlJKvuL2knNIVHFC+IiSIOeS+l3yo8=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=mRQYazPbq72oSunmh6AVdfciE8lWRNEeSEHGp7Gcpoktx5MLCAKN5WaGtYL4tRYGO cvhyB9Mj4ljHJhr2mlCNAw1a/tSyi2ArfO06FpiRf6nU4YK5ZBW2v/QejfsPvw+2DK 4VOFxfpseuDtt473gvuQa39Xz8gQLJLMFdj7H9Xs= From: Mark Rutland To: linux-arm-kernel@lists.infradead.org Subject: [RFC PATCH 02/13] arm64: preempt: Treat should_resched() as unlikely Date: Tue, 28 Jul 2026 13:38:48 +0100 Message-Id: <20260728123859.2911495-3-mark.rutland@arm.com> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20260728123859.2911495-1-mark.rutland@arm.com> References: <20260728123859.2911495-1-mark.rutland@arm.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.9.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20260728_053947_721913_57B8400A X-CRM114-Status: GOOD ( 11.19 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: mark.rutland@arm.com, vladimir.murzin@arm.com, peterz@infradead.org, catalin.marinas@arm.com, hca@linux.ibm.com, linux-kernel@vger.kernel.org, ruanjinjie@huawei.com, yang@os.amperecomputing.com, maz@kernel.org, will@kernel.org, ardb@kernel.org Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org The arm64 implementation of should_resched() doesn't treat the need to resched as unlikely, while all other implementations do, e.g. * asm-generic since: bdb43806589096ac ("sched: Extract the basic add/sub preempt_count modifiers") * x86 since: c2daa3bed53a8117 ("sched, x86: Provide a per-cpu preempt_count implementation") * s390 since: c360192bf4a8dc72 ("s390/preempt: move preempt_count to the lowcore") Do the same for arm64. Signed-off-by: Mark Rutland Cc: Ada Couprie Diaz Cc: Ard Biesheuvel Cc: Catalin Marinas Cc: Jinjie Ruan Cc: Marc Zyngier Cc: Peter Zijlstra Cc: Vladimir Murzin Cc: Will Deacon Cc: Yang Shi --- arch/arm64/include/asm/preempt.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/arch/arm64/include/asm/preempt.h b/arch/arm64/include/asm/preempt.h index ca2ad1a8db095..3ef24ab8f3399 100644 --- a/arch/arm64/include/asm/preempt.h +++ b/arch/arm64/include/asm/preempt.h @@ -58,7 +58,7 @@ static inline void __preempt_count_sub(int val) static inline bool should_resched(int preempt_offset) { u64 pc = READ_ONCE(current_thread_info()->preempt_count); - return pc == preempt_offset; + return unlikely(pc == preempt_offset); } static inline bool __preempt_count_dec_and_test(void) -- 2.30.2