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 BC001CAC592 for ; Fri, 19 Sep 2025 11:41:10 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:In-Reply-To:Content-Type: MIME-Version:References:Message-ID:Subject:Cc:To:From:Date:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=gP68eVLU1Zck8R5WUfUB+tPuu3+R0zTKlSRhm8mlIvM=; b=FpgXsZ8L71cU8sSOTn++vKqh8s F2wvKgYAHjDrtfw79zVfDkwN4f3Wn5A/kJYjsRaJHM04rk8ppyDRlwTKoHdHUIYd6vXESALHo5oxu C+fw0el9rcN89z59K6l1AC8GH4fF37LzWDMfIFBS4A/CetZEgYVOJ2c4V1xs25QpE85x+A4arE8HX BrXqj5R9G1smBlSYNWgUBFVx5hKlRvFc0/uKl5qXLdFkil3Bq7eF4tmuOeEh4h/QE11QzueIxogjh FY+r0U3X4lO1qjmN2hpYeW1XXCZIQy7LJE/AYEvVpXOn2LipgGAV+zX7LKDcg4rRGojbt+Wm6HpLS Iz3HLpcA==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1uzZU7-00000002j9I-0ZPM; Fri, 19 Sep 2025 11:41:03 +0000 Received: from tor.source.kernel.org ([2600:3c04:e001:324:0:1991:8:25]) by bombadil.infradead.org with esmtps (Exim 4.98.2 #2 (Red Hat Linux)) id 1uzZU6-00000002j99-30Gq for linux-arm-kernel@lists.infradead.org; Fri, 19 Sep 2025 11:41:02 +0000 Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by tor.source.kernel.org (Postfix) with ESMTP id 0969D60139; Fri, 19 Sep 2025 11:41:02 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id BFF3EC4CEF0; Fri, 19 Sep 2025 11:41:00 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1758282061; bh=792DYNCBkP3tBnabEABgwGFKr8gigP8l0yyHqaUtcz0=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=tP4QNoadn6CKvqSo+LZcTfeyko5AvnM+HUlQ717kWW5fmRqOuDxDfUGjZZhbAq7EF 4wA7JNCQH3LLZpN9wWcm4RuFmZIhZyolHeBh0pBFTXhvwMaGu14zH/BlvRmqw48343 EEAJuynhEW4VArF/EA3Di9Za6XL/d1jwOhyxHKOuuoIzeXzR446XDbPVNPdwd4ePBR IvORPciwbAPTN/AejQRQ1L7KdM8NfAApvvP25o9uQkd9eIvLGmWPJ/sCnzxNM0NQ7J e46FF1RiATQ8fK5m2NY5F1/iIMDpXlOU6wLT3RVdlXW/L4AgIAYkyIlfada25QLzOW LsaXWlPLLo7Zw== Date: Fri, 19 Sep 2025 12:40:57 +0100 From: Will Deacon To: Can Peng Cc: catalin.marinas@arm.com, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 1/1] arm/syscalls: mark syscall invocation as likely in invoke_syscall Message-ID: References: <20250919100042.497861-1-pengcan@kylinos.cn> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20250919100042.497861-1-pengcan@kylinos.cn> 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: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Fri, Sep 19, 2025 at 06:00:42PM +0800, Can Peng wrote: > The invoke_syscall() function is overwhelmingly called for > valid system call entries. Annotate the main path with likely() > to help the compiler generate better branch prediction hints, > reducing CPU pipeline stalls due to mispredictions. > > This is a micro-optimization targeting syscall-heavy workloads. Does it actually make a measurable difference? Will