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 10A96C433EF for ; Wed, 25 May 2022 16:56:04 +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=4TiAocjkgBUP8iWuywRLth3wcQlmUl3rXgV92ro3spY=; b=0kQvPY7lAj2lZ5 6suWOisw/4X5jCwK+0SGeKPEtBdVBxS+PhWcXIGQRtNHOUbYbYn09yGHVIsyimOcBv4K91lEsguOd cvRFTyScW7vWukda9Zw5UJFG6yVjqjm0Zc+a/RFA8qUnZ4IszPwBCNUfpRQoREmpAwB4cy/2I4+8n 9nm/hDo58EU/xYDTUJpbSa2UCdzUtKb5Hgbk6UteYKIcX7vNqB1DLXn9fB1MP0rpT9GUmnOx8YCpi EgG+4MCpbOAak5acF7le3pVxNLzOEMyvd/ADztej33ngxDOsSR7hTSB1rbZ4M+b0r9xfTLR0RHg+k Hx0bek1nV75L8Y6D/2+w==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1ntuHb-00Bu02-Ac; Wed, 25 May 2022 16:54:51 +0000 Received: from dfw.source.kernel.org ([2604:1380:4641:c500::1]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1ntuHX-00BtzO-Fz for linux-arm-kernel@lists.infradead.org; Wed, 25 May 2022 16:54:48 +0000 Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id B23EA616BA; Wed, 25 May 2022 16:54:46 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 06D9DC385B8; Wed, 25 May 2022 16:54:42 +0000 (UTC) Date: Wed, 25 May 2022 17:54:39 +0100 From: Catalin Marinas To: Barry Song <21cnbao@gmail.com> Cc: Andrew Morton , Will Deacon , Linux-MM , LAK , LKML , hanchuanhua , =?utf-8?B?5byg6K+X5piOKFNpbW9uIFpoYW5nKQ==?= , =?utf-8?B?6YOt5YGl?= , Barry Song , "Huang, Ying" , Minchan Kim , Johannes Weiner , Hugh Dickins , Shaohua Li , Rik van Riel , Andrea Arcangeli , Steven Price Subject: Re: [PATCH] arm64: enable THP_SWAP for arm64 Message-ID: References: <20220524071403.128644-1-21cnbao@gmail.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-20220525_095447_611180_13935D95 X-CRM114-Status: GOOD ( 21.05 ) 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 Wed, May 25, 2022 at 11:10:41PM +1200, Barry Song wrote: > On Wed, May 25, 2022 at 7:14 AM Catalin Marinas wrote: > > I think this should work and with your other proposal it would be > > limited to MTE pages: > > > > #define arch_thp_swp_supported(page) (!test_bit(PG_mte_tagged, &page->flags)) > > > > Are THP pages loaded from swap as a whole or are they split? IIRC the > > i can confirm thp is written as a whole through: > [ 90.622863] __swap_writepage+0xe8/0x580 > [ 90.622881] swap_writepage+0x44/0xf8 > [ 90.622891] pageout+0xe0/0x2a8 > [ 90.622906] shrink_page_list+0x9dc/0xde0 > [ 90.622917] shrink_inactive_list+0x1ec/0x3c8 > [ 90.622928] shrink_lruvec+0x3dc/0x628 > [ 90.622939] shrink_node+0x37c/0x6a0 > [ 90.622950] balance_pgdat+0x354/0x668 > [ 90.622961] kswapd+0x1e0/0x3c0 > [ 90.622972] kthread+0x110/0x120 > > but i have never got a backtrace in which thp is loaded as a whole though it > seems the code has this path: > int swap_readpage(struct page *page, bool synchronous) > { > ... > bio = bio_alloc(sis->bdev, 1, REQ_OP_READ, GFP_KERNEL); > bio->bi_iter.bi_sector = swap_page_sector(page); > bio->bi_end_io = end_swap_bio_read; > bio_add_page(bio, page, thp_size(page), 0); > ... > submit_bio(bio); > } > > > splitting still happens but after the swapping out finishes. Even if > > they are loaded as 4K pages, we still have the mte_save_tags() that only > > understands small pages currently, so rejecting THP pages is probably > > best. > > as anyway i don't have a mte-hardware to do a valid test to go any > further, so i will totally disable thp_swp for hardware having mte for > this moment in patch v2. It makes sense. If we decide to improve this for MTE, we'll change the arch check. Thanks. -- Catalin _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel