From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from pandora.armlinux.org.uk (pandora.armlinux.org.uk [78.32.30.218]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id D5BF053370; Wed, 31 Jul 2024 10:15:28 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=78.32.30.218 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1722420931; cv=none; b=sO5bTrQ+RAcnVqFHiDW4v3uO3xdK3YZSiCxTZmCKyAMod8AvCTIdy/pWdcM+Aw79h8wDD3i3/Hwyu+QhOmVvNXBkMw9uCZsLzUnkHswILJblcohDA/qN5NsmWHKOvgdOo+E9Plp/RyEo2gZ+N99f6BCd1uE2zGA7a0XZF6QZowc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1722420931; c=relaxed/simple; bh=z+VQEntqBxo5Gd2LvLOmLC4MpGmQveBzWyM3KmPsLAo=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=tqfkTJcZ2j+ghZC5nak4DTKU1r5Jvss66xaFX6/3ki+6rXPgvCVph0Klw4EJxTDu20XQkXAOZq0C4n/ENmEglfqr5EXnLbdG81R90M59sks97f999JRbc/aWW/zdTnGsjdYA+Dh3BgEaSNF8/k7aoT3pYqCD1CFjTYFkIp6GGmg= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=armlinux.org.uk; spf=none smtp.mailfrom=armlinux.org.uk; dkim=pass (2048-bit key) header.d=armlinux.org.uk header.i=@armlinux.org.uk header.b=fjZt/u+B; arc=none smtp.client-ip=78.32.30.218 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=armlinux.org.uk Authentication-Results: smtp.subspace.kernel.org; spf=none smtp.mailfrom=armlinux.org.uk Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=armlinux.org.uk header.i=@armlinux.org.uk header.b="fjZt/u+B" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=armlinux.org.uk; s=pandora-2019; h=Sender: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-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=qMBM7pjQFwnbFVqnUX8SB3vfklTZ2ocTvkMoeIJbxQ4=; b=fjZt/u+BQ9Vz/yMivaqlHmM58H OgLS6W+bfy2IQA0xkn3anddDj+f5ij2o3A9jTJHE96XREjU3SE0wSBJhRhZScfR9ZtdrT5Q5ni8cr 7pu7f7uEwLsruVT2u60fxv9OUHIJt1ZQsIvCrKPpx5gwjWcTx4WxDewRAEKyXWl/tm3WcGLvK7GDu ikow8z5kDrgmUGvoLWpdNsZHBamXkCPMVVumCAVXgRfKS20GQdJCVKMY9S8CVvDDXOFdUs1rTmzJ6 xbvjYTgPJTt7Qp2zA0PNedoTQBkcVPyEaHr7SalzMkgtBUyGbOzSZgRPFK0Xjmh2mWCBUDaUcmrsh zm7ia9JQ==; Received: from shell.armlinux.org.uk ([fd8f:7570:feb6:1:5054:ff:fe00:4ec]:47592) by pandora.armlinux.org.uk with esmtpsa (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.96) (envelope-from ) id 1sZ6ME-00005e-0w; Wed, 31 Jul 2024 11:14:58 +0100 Received: from linux by shell.armlinux.org.uk with local (Exim 4.94.2) (envelope-from ) id 1sZ6MD-00067m-VX; Wed, 31 Jul 2024 11:14:58 +0100 Date: Wed, 31 Jul 2024 11:14:57 +0100 From: "Russell King (Oracle)" To: Jinjie Ruan Cc: arnd@arndb.de, afd@ti.com, akpm@linux-foundation.org, linus.walleij@linaro.org, eric.devolder@oracle.com, robh@kernel.org, vincent.whitchurch@axis.com, bhe@redhat.com, nico@fluxnic.net, ardb@kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org Subject: Re: [PATCH] ARM: support PREEMPT_DYNAMIC Message-ID: References: <20240620090028.729373-1-ruanjinjie@huawei.com> <79a3de7c-21da-12ce-8372-9c9029c237ac@huawei.com> <034499ea-2cd6-8775-ee94-771cbecd4cdb@huawei.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <034499ea-2cd6-8775-ee94-771cbecd4cdb@huawei.com> Sender: Russell King (Oracle) On Wed, Jul 31, 2024 at 06:03:11PM +0800, Jinjie Ruan wrote: > On 2024/7/31 16:24, Russell King (Oracle) wrote: > > On Wed, Jul 31, 2024 at 10:07:53AM +0800, Jinjie Ruan wrote: > >>> #ifdef CONFIG_PREEMPTION > >>> +#ifdef CONFIG_PREEMPT_DYNAMIC > >>> + bl need_irq_preemption > >>> + cmp r0, #0 > >>> + beq 2f > >>> +#endif > > > > Depending on the interrupt rate, this can be regarded as a fast path, > > it would be nice if we could find a way to use static branches in > > assembly code. > It seems to be hard to use static keys in assembly code. > > By the way, currently, most architectures have simplified assembly code > and implemented its most functions in C functions. Does arm32 have this > plan? arm32 is effectively in maintenance mode; very little active development is occuring. So, there are no plans to change the code without good reason (as code changes without reason will needlessly affect its stability.) -- RMK's Patch system: https://www.armlinux.org.uk/developer/patches/ FTTP is here! 80Mbps down 10Mbps up. Decent connectivity at last!