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 16132EA4FB8 for ; Mon, 23 Feb 2026 13:00:40 +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:In-Reply-To:MIME-Version:References: Message-ID:Subject:Cc:To:From:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=HHF0Q2AP72O3Rp8aeSmh7W/MZF15LXh/ggKiwSxeR+E=; b=f7B5xMZFFxVYRM SeFfj1+0USO+8DNZ+fnurduOvMmARvyg2Ujz4tLYMPmnixD/vflzWq0xHei9xaOw/8jG4IBV8hZO8 COFIJsSZ6UJELwz/1hIhscPlSa6NIgKMnHjUumFF7xYnSy2z0RLCxndVS0kbsPYWE6scnfCnW0vsx r2gm/1wHPyNOVvok5e8Wah1C2D3lESYQWZSRHwguUwWrQrNqU4t/Pjxb9jEVn7xru3KHElQYbpHtk YsRppnZwdlMSNlty9A2y3sx7af9ikPpBVplcS8sp0l8DlwDnTB9EWBQoy83lG1GkcFu9Oq9Qmm8k9 G2IGk3j/Lwg8kHV9Lywg==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1vuVY8-00000000Jm0-2K9p; Mon, 23 Feb 2026 13:00:32 +0000 Received: from tor.source.kernel.org ([172.105.4.254]) by bombadil.infradead.org with esmtps (Exim 4.98.2 #2 (Red Hat Linux)) id 1vuVY7-00000000Jla-1y4y; Mon, 23 Feb 2026 13:00:31 +0000 Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by tor.source.kernel.org (Postfix) with ESMTP id 6FF9A600C4; Mon, 23 Feb 2026 13:00:30 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 18D62C116C6; Mon, 23 Feb 2026 13:00:25 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1771851630; bh=uOtJDy2FyPxpMhP2bRO2gFMv/2nj4Vw849MMg7jCtgQ=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=clGrAsM1eO4t5380MKOhdLbYwfD37kNqsjhSPZfNmBaOz+46Aab5ZPI93qEZEU5nS DcwHN+ArfBxcohFQnPXImXwzoJa/FHhgA0Z9jrj3wh7XDmC3M+vqCxsmgfy4RSA5tt kkQBqXWtWNzYKtp35Gc+GZEl+P9QXOmoXkBRlX43RAI4LY7FuHvlHjYGeyDpC+RGBT tUqkFw7eNYiDbxZ/wRx1d7LsNHhur4YAEp9jJv9TLYXDgW2OX+BkEv5rWEz9yWRU0b nbhXvY0Av3j2c9EfjiEXgY8ljwW0Re4YGY8ls3P4Q9In+IRfQjjZq3NlZG1S3pcp07 1d/WixW1O9Mnw== Date: Mon, 23 Feb 2026 20:41:55 +0800 From: Jisheng Zhang To: Thomas Gleixner , ardb@kernel.org, mark.rutland@arm.com Cc: Catalin Marinas , Will Deacon , Arnd Bergmann , Paul Walmsley , Palmer Dabbelt , Albert Ou , Alexandre Ghiti , Guo Ren , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org, linux-riscv@lists.infradead.org, linux-csky@vger.kernel.org Subject: Re: [PATCH 2/3] genirq: use runtime constant to optimize handle_arch_irq access Message-ID: References: <20260220090922.1506-1-jszhang@kernel.org> <20260220090922.1506-3-jszhang@kernel.org> <877bs4wi0c.ffs@tglx> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <877bs4wi0c.ffs@tglx> 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: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-riscv" Errors-To: linux-riscv-bounces+linux-riscv=archiver.kernel.org@lists.infradead.org On Sun, Feb 22, 2026 at 11:06:11PM +0100, Thomas Gleixner wrote: > On Fri, Feb 20 2026 at 17:09, Jisheng Zhang wrote: > > Currently, on GENERIC_IRQ_MULTI_HANDLER platforms, the handle_arch_irq > > is a pointer which is set during booting, and every irq processing needs > > to access it, so it sits in hot code path. We can use the > > runtime constant mechanism which was introduced by Linus to speed up > > its accessing. > > The proper solution is to use a static call and update it in > set_handle_irq(). That removes the complete indirect call issue from > the hot path. + Ard, Mark, Good idea. The remaining problem is no static call support for current GENERIC_IRQ_MULTI_HANDLER (or similar, arm64 e.g) platforms. For arm64, Ard tried to add the static call support[1] in 2021, but Mark concerned "compiler could easily violate our expectations in future"[2], and asked for static calls "critical rather than a nice-to-have" usage. Hi Ard, Mark, Could this irq performance improvement be used as a "critical" usage for arm64 static call? Per my test, about 6.5% improvement was seen on quad CA55. Another alternative: disable static call if CFI is enabled, and give the platform/SoC users chance to enable static call to benefit from it. Any comment is appreciated. Thanks [1] https://www.spinics.net/lists/arm-kernel/msg931861.html [2] https://www.spinics.net/lists/arm-kernel/msg932481.html > > Thanks, > > tglx _______________________________________________ linux-riscv mailing list linux-riscv@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-riscv