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 BD8B8C43334 for ; Tue, 7 Jun 2022 09:55:27 +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=djluNwYw0iom2eotMS+cDBgd+3J9dCdtnjjq+6oReM4=; b=RXPQV82nIHL7Wy zSdOVIJHrp6k7qSmIFs2JPhIF9H+Hf5HX8LwaB8TbtDEtfRvQCu8JZ9ICc5D5pEEAUQg6c5R7yZnD 3DuDqbyhD6OmHffIiBG1chrjG1qD5d3eSNryQ1EnKUmvFdXNv+PBHQfgP9mLASB8k2year3GCF7Ol YYTJG08Z4ydGyooapOZnId34icm4DPqRkZWUla/+GTkJw0/PB/Y2jEKSbYfr2C8b/rVGg9wGMDgEF lHXJwE6V7001adjaLwsk0T4Ujlu18nwJgfIPYz3AXqqmm2bBkNbS9Uqe0uAx4ZHCbACjFzPciBBYb lIjkSYYKJ+cT0OHBAmOw==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1nyVuV-006R7s-5Q; Tue, 07 Jun 2022 09:54:03 +0000 Received: from pandora.armlinux.org.uk ([2001:4d48:ad52:32c8:5054:ff:fe00:142]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1nyVl9-006Ltl-4a for linux-arm-kernel@lists.infradead.org; Tue, 07 Jun 2022 09:44:24 +0000 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=7iZBUDNZml+y6LVCsu7mPiADxJ5RvtS1pzLo0QXbcxE=; b=lvd2JwuZiYcqia5o/VIYiQrRFG 5Y+ZxlVS0cE5TJmImn5aWjAylBUtFPQ0O25RKEIU0y24dr1B/2PvL+/EkqgT0kmxI5JCwWt1p+Mdq w+ZuRCMv5ev2HR9bXeCcsmsGNyzd8Oi2x/gBL4QDZH0kGgL8ABxEIj5R7H8eW38KRoDV3s8ifsDZm 68nHzYBXuSixntx/U00mXh1xF1IBRNJgU6bLapBJmx0IZBmtQYIajvmGWtXI0CspvxPhGA9WjXdrq iPVuPfp8bMG8eMFARW81VBE2xf6oiVqSpOXI2t5+/HMhYZpJkl1RgCgenSXNqGMDYx9gd/qGNlY80 A9NB9UYw==; Received: from shell.armlinux.org.uk ([fd8f:7570:feb6:1:5054:ff:fe00:4ec]:60988) by pandora.armlinux.org.uk with esmtpsa (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.94.2) (envelope-from ) id 1nyVl1-00038t-JT; Tue, 07 Jun 2022 10:44:15 +0100 Received: from linux by shell.armlinux.org.uk with local (Exim 4.94.2) (envelope-from ) id 1nyVky-0000h6-Un; Tue, 07 Jun 2022 10:44:12 +0100 Date: Tue, 7 Jun 2022 10:44:12 +0100 From: "Russell King (Oracle)" To: Arnd Bergmann Cc: Matthew Wilcox , Joakim Tjernlund , "linux-mm@kvack.org" , Linux ARM Subject: Re: Finding kernel RAM consumers ? Message-ID: References: <70b4e1e46d9d63275a0dfe90f96f40ea14d89f0c.camel@infinera.com> <88dfec5a1c98f4eb71e23cafe89db4395ea12811.camel@infinera.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20220607_024423_269996_F071FB97 X-CRM114-Status: GOOD ( 23.25 ) 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: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Tue, Jun 07, 2022 at 10:38:54AM +0200, Arnd Bergmann wrote: > On Tue, Jun 7, 2022 at 7:41 AM Alexander Dahl wrote: > > Am Fri, Jun 03, 2022 at 08:11:31PM +0200 schrieb Arnd Bergmann: > > > On Fri, Jun 3, 2022 at 7:29 PM Matthew Wilcox wrote: > > > > > > I think this is a case of "patches welcome". Nobody has really needed > > > this so far, but as even the smaller machines are slowly migrating from > > > 32-bit to 64-bit cores, optimizing this will get interesting for more > > > developers. There are probably other low-hanging > > > fruit that you can address after figuring out. > > > > The SiP variants of at91 SAMA5D2 (armv7) or SAM9x60 (armv5) come with > > 64 MiB or 128 MiB, and given the latter is a new SoC announced only > > two or three years ago, requiring at least 256 MiB would be at best > > unfortunate. Given those SoCs are used in industrial applications > > with very long support times, I think 32bit ARM will stay for years, > > even with new products. > > Yes, of course, and there is nothing wrong with that. We already see > Cortex-A7 cores down to 7nm, all running Linux, and I expect there > will likely be another 5 to 10 years of new 32-bit chips, and then another > 10 years of people putting the existing chips into production, and after > that a slow decline of users updating their kernels before supporting > 32-bit hardware becomes too expensive to support in the kernel. It should be noted that 20 years puts us past the 2038 32-bit time_t wrap problem - and although there's been work to address that in the UAPI, that doesn't mean that userspace will cope. Anyone deploying a system that is expected to still be live beyond the end of 32-bit time_t had better be testing their userspace for that event now! -- RMK's Patch system: https://www.armlinux.org.uk/developer/patches/ FTTP is here! 40Mbps down 10Mbps up. Decent connectivity at last! _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel