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 X-Spam-Level: X-Spam-Status: No, score=-4.1 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id D05DAC388F9 for ; Wed, 21 Oct 2020 12:46:48 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 726C92224E for ; Wed, 21 Oct 2020 12:46:48 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1603284408; bh=ttXp3ovL74pvsFHzn70xAtSuQ5PCnDzGKQbu4q5Oj+g=; h=References:In-Reply-To:From:Date:Subject:To:Cc:List-ID:From; b=mDJ4x1/z1y431LdK+u8ONmtUAVNcNQL4nuPODPE8bP24PtM79ClgGL2w3OSqllWlV dlyN+OqEVyW7UKqgXcSDpiCzwnrFuTCUUnMNl+SrfGF3ChQtH7RFdVa1c+fQx808fO Qk/SFMUif9hm/elgTmWSH35Xkb8wV0ljNz860BEg= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2440861AbgJUMqr (ORCPT ); Wed, 21 Oct 2020 08:46:47 -0400 Received: from mail.kernel.org ([198.145.29.99]:43968 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2437025AbgJUMqq (ORCPT ); Wed, 21 Oct 2020 08:46:46 -0400 Received: from mail-qt1-f173.google.com (mail-qt1-f173.google.com [209.85.160.173]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id A3909223BF for ; Wed, 21 Oct 2020 12:46:45 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1603284405; bh=ttXp3ovL74pvsFHzn70xAtSuQ5PCnDzGKQbu4q5Oj+g=; h=References:In-Reply-To:From:Date:Subject:To:Cc:From; b=bWwHqUVe7SwWjbBhWQfnc1gNPHZxfTBeszYdkfWpiqaHp1Ub1JrfyZPkblZzAErMt 8+FbAjYbP14i4MZiJxhgGe/KZE6xBWhqJAfMAcOA+LqCXNbYBDntywVRcfW8xjqbwg SFAAiAHU7qxorTJqRAASlmvTaBR4kuH7G7jTGaEc= Received: by mail-qt1-f173.google.com with SMTP id m9so1884992qth.7 for ; Wed, 21 Oct 2020 05:46:45 -0700 (PDT) X-Gm-Message-State: AOAM533Gh8devLGAq/tNNrbrAccTvnAyjb0BD0406A+zh3zp6vkTjs7w xkEBDGDb3dzZc+3kqgw7Asnq/89stg/swdd3ftI= X-Google-Smtp-Source: ABdhPJyAmqnWKXXVYMHBrBwQ8vRAy5SXr0Z8q5x0gqYcFsbtiIr0nZUN9iiiouSsLjFc5Rif7/kUhm+TwOPAM49mtw4= X-Received: by 2002:ac8:1ba6:: with SMTP id z35mr2845432qtj.204.1603284404668; Wed, 21 Oct 2020 05:46:44 -0700 (PDT) MIME-Version: 1.0 References: <1602141333-17822-1-git-send-email-maninder1.s@samsung.com> <20201008083015.GK1551@shell.armlinux.org.uk> <20201021123400.GK1551@shell.armlinux.org.uk> In-Reply-To: <20201021123400.GK1551@shell.armlinux.org.uk> From: Arnd Bergmann Date: Wed, 21 Oct 2020 14:46:28 +0200 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [PATCH 0/3] IRQ stack support for ARM To: Russell King - ARM Linux admin Cc: Arnd Bergmann , Maninder Singh , v.narang@samsung.com, a.sahrawat@samsung.com, Andrew Morton , Marc Zyngier , Sebastian Andrzej Siewior , Vincent Whitchurch , Nick Desaulniers , "linux-kernel@vger.kernel.org" , Valentin Schneider , Dmitry Safonov <0x7f454c46@gmail.com>, Thomas Gleixner , Nathan Huckleberry , Will Deacon , Jian Cai , Linux ARM , =?UTF-8?Q?Uwe_Kleine=2DK=C3=B6nig?= Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Oct 21, 2020 at 2:34 PM Russell King - ARM Linux admin wrote: > > We don't do it because we don't have a separate register to be able > to store the thread_info pointer, and copying that lump between the > SVC and IRQ stack will add massively to IRQ latency, especially for > older machines. I forwarded my other reply as well, in which I suggested using CONFIG_THREAD_INFO_IN_TASK, wouldn't that solve the problem? Arnd