From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Hildenbrand Subject: Re: [PATCH v6 00/33] Split ptdesc from struct page Date: Tue, 27 Jun 2023 09:14:29 +0200 Message-ID: References: <20230627031431.29653-1-vishal.moola@gmail.com> Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Return-path: DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:Content-Type: Content-Transfer-Encoding:List-Subscribe:List-Help:List-Post:List-Archive: List-Unsubscribe:List-Id:In-Reply-To:From:References:Cc:To:Subject: MIME-Version:Date:Message-ID:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=JMo470WvEChn2ztx7PdY56ZRWeSxU2eKyKWa+7ZOkjQ=; b=KBhARn6lq13B3I R29tYotEQpO5z457cvhuWH/X73PV0VgYc2HS4m6CcZurqmjz6X/qTFkEaL7pmqkKyUjmu+OjxlRjz +J25jIXpb/euBrb2R24RtfokWuqFedM7DqvQ5tXBaB3gWwU26q0m4GXuJb3zVfdwp8C8daDcgFbeq KuLyvU9+yhXw5EI+X9x8MmHLIfXJpFbr29fiPV4/+Uii6XixJqTKjKYoyPtpFWAKRu5HTJpNJefqg tqi1xON1eaM0RBVqbON+68C7hnMI2nrYUvPGjwmIiL0ax5W8cuciNnHdpT4gcVSd7287fisTD1L0Z W8BV1mCXsdWlGi1IqJXg==; DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1687850074; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=N1scKhPxxz/YxysE64BuheSdyQmgV4XhiinPf6icWX8=; b=Dn/UUUaYUbwjIQ68CDVKfTpiqL3HVvDYjn8rQZkyUA8eNqQO6LCQ/4zOQJK7dJVYbVVVyr UN/cVIcuku792pRTFsNpUKEBqx+imPELoNIZypUwSqq3rjs7/KceX7XOvthKDTekoc2Rph bI4CMZbD419KTcuqOOYsw1OhLXkM9S8= In-Reply-To: Content-Language: en-US List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-riscv" Errors-To: linux-riscv-bounces+glpr-linux-riscv=m.gmane-mx.org@lists.infradead.org Content-Type: text/plain; charset="us-ascii"; format="flowed" To: Hugh Dickins , "Vishal Moola (Oracle)" Cc: Andrew Morton , Matthew Wilcox , linux-mm@kvack.org, linux-arch@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-csky@vger.kernel.org, linux-hexagon@vger.kernel.org, loongarch@lists.linux.dev, linux-m68k@lists.linux-m68k.org, linux-mips@vger.kernel.org, linux-openrisc@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-riscv@lists.infradead.org, linux-s390@vger.kernel.org, linux-sh@vger.kernel.org, sparclinux@vger.kernel.org, linux-um@lists.infradead.org, xen-devel@lists.xenproject.org, kvm@vger.kernel.org, Catalin Marinas , Huacai Chen , Geert Uytterhoeven , Thomas Bogendoerfer , Dinh Nguyen , Jonas Bonn , Claudio Imbrenda , Paul Walmsley On 27.06.23 06:44, Hugh Dickins wrote: > On Mon, 26 Jun 2023, Vishal Moola (Oracle) wrote: > >> The MM subsystem is trying to shrink struct page. This patchset >> introduces a memory descriptor for page table tracking - struct ptdesc. > ... >> 39 files changed, 686 insertions(+), 455 deletions(-) > > I don't see the point of this patchset: to me it is just obfuscation of > the present-day tight relationship between page table and struct page. > > Matthew already explained: > >> The intent is to get ptdescs to be dynamically allocated at some point >> in the ~2-3 years out future when we have finished the folio project ... > > So in a kindly mood, I'd say that this patchset is ahead of its time. > But I can certainly adapt to it, if everyone else sees some point to it. I share your thoughts, that code churn which will help eventually in the far, far future (not wanting to sound too pessimistic, but it's not going to be there tomorrow ;) ). However, if it's just the same as the other conversions we already did (e.g., struct slab), then I guess there is no reason to stop now -- the obfuscation already happened. ... or is there a difference regarding this conversion and the previous ones? -- Cheers, David / dhildenb