From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx138.postini.com [74.125.245.138]) by kanga.kvack.org (Postfix) with SMTP id 6C48D6B004A for ; Sat, 14 Apr 2012 08:15:29 -0400 (EDT) Message-ID: <1334405716.2528.88.camel@twins> Subject: Re: [Lsf] [RFC] writeback and cgroup From: Peter Zijlstra Date: Sat, 14 Apr 2012 14:15:16 +0200 In-Reply-To: References: <20120403183655.GA23106@dhcp-172-17-108-109.mtv.corp.google.com> <20120404145134.GC12676@redhat.com> <20120404184909.GB29686@dhcp-172-17-108-109.mtv.corp.google.com> Content-Type: text/plain; charset="ISO-8859-1" Content-Transfer-Encoding: quoted-printable Mime-Version: 1.0 Sender: owner-linux-mm@kvack.org List-ID: To: Steve French Cc: Tejun Heo , ctalbott@google.com, rni@google.com, andrea@betterlinux.com, containers@lists.linux-foundation.org, linux-kernel@vger.kernel.org, lsf@lists.linux-foundation.org, linux-mm@kvack.org, jmoyer@redhat.com, lizefan@huawei.com, linux-fsdevel@vger.kernel.org, cgroups@vger.kernel.org On Wed, 2012-04-04 at 14:23 -0500, Steve French wrote: > Current use of bdi is a little hard to understand since > there are 25+ fields in the structure. =20 Filesystems only need a small fraction of those. In particular, backing_dev_info::name -- string backing_dev_info::ra_pages -- number of read-ahead-pages backing_dev_info::capability -- see BDI_CAP_* =20 One should properly initialize/destroy the thing using: bdi_init()/bdi_destroy() Furthermore, it has hooks into the regular page-writeback stuff: test_{set,clear}_page_writeback()/bdi_writeout_inc() set_page_dirty()/account_page_dirtied() =20 but also allows filesystems to do custom stuff, see FUSE for example. The only other bit is the pressure valve, aka. {set,clear}_bdi_congested(). Which really is rather broken and of dubious value. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: email@kvack.org