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=-2.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,USER_AGENT_MUTT autolearn=unavailable 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 113ECC43441 for ; Mon, 19 Nov 2018 09:04:49 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id D6EBE20823 for ; Mon, 19 Nov 2018 09:04:48 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org D6EBE20823 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-btrfs-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726993AbeKST1l (ORCPT ); Mon, 19 Nov 2018 14:27:41 -0500 Received: from mx1.redhat.com ([209.132.183.28]:60484 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726088AbeKST1l (ORCPT ); Mon, 19 Nov 2018 14:27:41 -0500 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.phx2.redhat.com [10.5.11.15]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 16E2D3082E44; Mon, 19 Nov 2018 09:04:41 +0000 (UTC) Received: from ming.t460p (ovpn-8-26.pek2.redhat.com [10.72.8.26]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 549F55D757; Mon, 19 Nov 2018 09:04:20 +0000 (UTC) Date: Mon, 19 Nov 2018 17:04:16 +0800 From: Ming Lei To: Omar Sandoval , Huang Ying Cc: Jens Axboe , linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, Dave Chinner , Kent Overstreet , Mike Snitzer , dm-devel@redhat.com, Alexander Viro , linux-fsdevel@vger.kernel.org, Shaohua Li , linux-raid@vger.kernel.org, linux-erofs@lists.ozlabs.org, David Sterba , linux-btrfs@vger.kernel.org, "Darrick J . Wong" , linux-xfs@vger.kernel.org, Gao Xiang , Christoph Hellwig , Theodore Ts'o , linux-ext4@vger.kernel.org, Coly Li , linux-bcache@vger.kernel.org, Boaz Harrosh , Bob Peterson , cluster-devel@redhat.com Subject: Re: [PATCH V10 15/19] block: always define BIO_MAX_PAGES as 256 Message-ID: <20181119090415.GM16736@ming.t460p> References: <20181115085306.9910-1-ming.lei@redhat.com> <20181115085306.9910-16-ming.lei@redhat.com> <20181116015936.GJ23828@vader> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20181116015936.GJ23828@vader> User-Agent: Mutt/1.9.1 (2017-09-22) X-Scanned-By: MIMEDefang 2.79 on 10.5.11.15 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.46]); Mon, 19 Nov 2018 09:04:41 +0000 (UTC) Sender: linux-btrfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org On Thu, Nov 15, 2018 at 05:59:36PM -0800, Omar Sandoval wrote: > On Thu, Nov 15, 2018 at 04:53:02PM +0800, Ming Lei wrote: > > Now multi-page bvec can cover CONFIG_THP_SWAP, so we don't need to > > increase BIO_MAX_PAGES for it. > > You mentioned to it in the cover letter, but this needs more explanation > in the commit message. Why did CONFIG_THP_SWAP require > 256? Why does > multipage bvecs remove that requirement? CONFIG_THP_SWAP needs to split one TH page into normal pages and adds them all to one bio. With multipage-bvec, it just takes one bvec to hold them all. thanks, Ming