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=-2.1 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 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 D5EA5ECE588 for ; Tue, 15 Oct 2019 11:35:51 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id A40CF21848 for ; Tue, 15 Oct 2019 11:35:51 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="ZHcs9NvG" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728618AbfJOLfu (ORCPT ); Tue, 15 Oct 2019 07:35:50 -0400 Received: from bombadil.infradead.org ([198.137.202.133]:35758 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728061AbfJOLfu (ORCPT ); Tue, 15 Oct 2019 07:35:50 -0400 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.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: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=zPxLUku4BuRDt5+SJLEWDEFub4QOmiwDKS+8qep8Bak=; b=ZHcs9NvGWGV7QE24aroVDMFzT enbdNKTsTAoSDcwBixZFb4uNCsCnqIbv1+8tmPSVDwWFaJEeL/UR0qAqdTaKaFm2qTkRY7f/HR9fG 5cn0JNSc2cZuOe6PU1MQ+kPr0wQnXdx8Yef0x6yStoMAQM5hmEc7++Hel1avjJPK0605o30gna1Rb v8ToEKIHyQ/n7YuUPgNPvDCNZ+fHM6bhkLdcQOFXQzoR6kJPontTaLYhK9ozqj7Z4tO9n9/+/ZoHY 0yfevKwaeNoWRmiLyweSOvMbYWfkBHitiZuWxyF/APSIJI2lu2Bl4FRSvMIe6xK7V5N0l7sAaoMfZ PuSsGLzMQ==; Received: from willy by bombadil.infradead.org with local (Exim 4.92.3 #3 (Red Hat Linux)) id 1iKL7F-0006DH-0D; Tue, 15 Oct 2019 11:35:49 +0000 Date: Tue, 15 Oct 2019 04:35:48 -0700 From: Matthew Wilcox To: Naohiro Aota Cc: linux-mm@kvack.org, linux-fsdevel@vger.kernel.org, linux-block@vger.kernel.org, Andrew Morton Subject: Project idea: Swap to zoned block devices Message-ID: <20191015113548.GD32665@bombadil.infradead.org> References: <20191015043827.160444-1-naohiro.aota@wdc.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20191015043827.160444-1-naohiro.aota@wdc.com> User-Agent: Mutt/1.12.1 (2019-06-15) Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org On Tue, Oct 15, 2019 at 01:38:27PM +0900, Naohiro Aota wrote: > A zoned block device consists of a number of zones. Zones are > eitherconventional and accepting random writes or sequential and > requiringthat writes be issued in LBA order from each zone write > pointerposition. For the write restriction, zoned block devices are > notsuitable for a swap device. Disallow swapon on them. That's unfortunate. I wonder what it would take to make the swap code be suitable for zoned devices. It might even perform better on conventional drives since swapout would be a large linear write. Swapin would be a fragmented, seeky set of reads, but this would seem like an excellent university project.