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 kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id BE0EBC67861 for ; Mon, 8 Apr 2024 16:31:05 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 1D77F6B0083; Mon, 8 Apr 2024 12:31:05 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 186D16B0087; Mon, 8 Apr 2024 12:31:05 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 076106B0089; Mon, 8 Apr 2024 12:31:05 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0015.hostedemail.com [216.40.44.15]) by kanga.kvack.org (Postfix) with ESMTP id E17C46B0083 for ; Mon, 8 Apr 2024 12:31:04 -0400 (EDT) Received: from smtpin10.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay04.hostedemail.com (Postfix) with ESMTP id 7A1BD1A0134 for ; Mon, 8 Apr 2024 16:31:04 +0000 (UTC) X-FDA: 81986904048.10.23B737F Received: from casper.infradead.org (casper.infradead.org [90.155.50.34]) by imf13.hostedemail.com (Postfix) with ESMTP id 9E50D20026 for ; Mon, 8 Apr 2024 16:31:01 +0000 (UTC) Authentication-Results: imf13.hostedemail.com; dkim=pass header.d=infradead.org header.s=casper.20170209 header.b=XFujNQgu; spf=none (imf13.hostedemail.com: domain of willy@infradead.org has no SPF policy when checking 90.155.50.34) smtp.mailfrom=willy@infradead.org; dmarc=none ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1712593861; h=from:from:sender: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: in-reply-to:in-reply-to:references:references:dkim-signature; bh=JYkRh73Rl5CPfFkG4OUVhpuHbyef7jw0zP01jOyXuO4=; b=5j5AWDC42O32T0fi0H6mL/vc6jG+NB3FVhtz4Dg5JchBsjRSgexuRQUG5P/R7hJVILKFXb pSlK1jIAwPY2R/xJGlvQ/vgmaiqGVyfOwFqvFBoBUsvf5KovO90v4vpwMwieftFElE0jrO caZajAnpiTnwBMIxkTShNukthuz4Qx8= ARC-Authentication-Results: i=1; imf13.hostedemail.com; dkim=pass header.d=infradead.org header.s=casper.20170209 header.b=XFujNQgu; spf=none (imf13.hostedemail.com: domain of willy@infradead.org has no SPF policy when checking 90.155.50.34) smtp.mailfrom=willy@infradead.org; dmarc=none ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1712593861; a=rsa-sha256; cv=none; b=rLSIcZkNkyQNjC3kvF1/D6rltIfgl8X9P2Tng8ulatwGzeY1/CumfMUMuEQCwoK2srcuvB CrL4+K05xt9SbeUUn9ObhLKmDkpb110QXIICHFnVGyeNfqQ/kCB14lMf6K5alI3HAKzU9o Dh6MQMgonL8SIQuN3omdKukOCU2c+bI= DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=JYkRh73Rl5CPfFkG4OUVhpuHbyef7jw0zP01jOyXuO4=; b=XFujNQguwCIszW636IbDD60pxw Qrt2znYHOgSRqH4pmyEfYqkON0Sp3e3zL9N7Pod5TNEiA/lw7S45viJ863a68V6wrdTnJzXmryYBn JeBdxV/23b4BGxwhxeIWwK4SP2qMGlMeLZCLHb53xu/4EXHU4nSIiak/s3vTqvoLs2uPZS/1xObR/ l3bKS0VybysiJiBtWqR9XpU2tEpHreXgXVGLBYgQjQvZCpYHZvNfHIxYq4IaQy+LdhiyTjJnvc78l wKuRVMgt7O18pvTWL41TxpdaJdXkZZ+ZKxN3vXdqpKDa2kRRuzHR19oYAvWZppbnw282RXHJVAXjF rvj1birw==; Received: from willy by casper.infradead.org with local (Exim 4.97.1 #2 (Red Hat Linux)) id 1rtrtT-00000000CCo-395u; Mon, 08 Apr 2024 16:30:51 +0000 Date: Mon, 8 Apr 2024 17:30:51 +0100 From: Matthew Wilcox To: "Christoph Lameter (Ampere)" Cc: Jonathan Cameron , Yang Shi , lsf-pc@lists.linux-foundation.org, olivier.singla@amperecomputing.com, Linux MM , Michal Hocko , Dan Williams Subject: Re: [LSF/MM/BPF TOPIC] Multi-sized THP performance benchmarks and analysis on ARM64 Message-ID: References: <20240401191614.00007c83@Huawei.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Rspamd-Queue-Id: 9E50D20026 X-Rspam-User: X-Stat-Signature: c83myyp5rq5bmmw5rtqguhcn399t7noa X-Rspamd-Server: rspam01 X-HE-Tag: 1712593861-898020 X-HE-Meta: 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 f+W+wFOa NWKIQeVM42wkDQ/1AXIdkLjAn5x/6gIMmOczAvNaucNYLpAAfXxSJaN/JIlZ4uRybGJenJ/0XmbSANFvOiox4r3xgKNq7Zkh90TM+oWZhRFXoJsXLvnFZOKXdAIkXdYxSDzpLD4TLnqjmk2c= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Thu, Apr 04, 2024 at 11:57:03AM -0700, Christoph Lameter (Ampere) wrote: > On Mon, 1 Apr 2024, Jonathan Cameron wrote: > > > Sounds like useful data, but is it a suitable topic for LSF-MM? > > What open questions etc is it raising? > > > mTHP is new functionality that will require additional work to support more > use cases. It is also unclear at this point in what usecases mTHP is useful > and where no benefit can so far be seen. Also the effect of coalescing > multiple PTE entries into one TLB entry is new to MM (CONT_PTE). > > Ultimately it would be useful to have mTHP support also provide larger > blocksize capabilities for filesystem etc etc. mTHP needs to mature and an > analysis of the arguable a bit experimental state of affairs can help a lot > in getting there. Have you been paying attention to anything that's been happening in Linux development in the last three years? 7b230db3b8d3 introduced folios in December 2020 (was merged in November 2021 for v5.16). v5.17 (March 2022) did everything short of enabling large folios for the page cache, which landed in v5.18 (May 2022). We started using cont-PTEs for large folios in August 2023. Again, the page cache led the way here and we're just adding support for anonymous large folios (called mTHP) now. There's still a ton of work to do, but we've been busy doing it since LSFMM in Puerto Rico (2019) with READ_ONLY_THP_FOR_FS being the very first result from the group of interested developers. And if you haven't seen the results that Ryan Roberts has posted for the tests he's run, I suggest you look them up. He does a great job of breaking down how much benefit he sees from the hardware side (use of contPTE) vs the software side (shorter LRU lists, fewer atomic ops).