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 2429FC433FE for ; Tue, 11 Oct 2022 01:01:15 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 795DA6B0072; Mon, 10 Oct 2022 21:01:14 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 744056B0073; Mon, 10 Oct 2022 21:01:14 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 633936B0074; Mon, 10 Oct 2022 21:01:14 -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 50ADE6B0072 for ; Mon, 10 Oct 2022 21:01:14 -0400 (EDT) Received: from smtpin29.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay07.hostedemail.com (Postfix) with ESMTP id 02F4D160F84 for ; Tue, 11 Oct 2022 01:01:13 +0000 (UTC) X-FDA: 80006864868.29.C79D021 Received: from 66-220-144-178.mail-mxout.facebook.com (66-220-144-178.mail-mxout.facebook.com [66.220.144.178]) by imf28.hostedemail.com (Postfix) with ESMTP id 8358BC0032 for ; Tue, 11 Oct 2022 01:01:12 +0000 (UTC) Received: by dev1180.prn1.facebook.com (Postfix, from userid 425415) id E1F2834BDD53; Mon, 10 Oct 2022 18:00:58 -0700 (PDT) From: Stefan Roesch To: kernel-team@fb.com, linux-block@vger.kernel.org, linux-mm@kvack.org Cc: shr@devkernel.io, axboe@kernel.dk, clm@meta.com Subject: [RFC PATCH v1 00/14] mm/block: add bdi sysfs knobs Date: Mon, 10 Oct 2022 18:00:30 -0700 Message-Id: <20221011010044.851537-1-shr@devkernel.io> X-Mailer: git-send-email 2.30.2 MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1665450072; 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-transfer-encoding:content-transfer-encoding: in-reply-to:references; bh=bXQ6BrqrvLg4QN+60N4Dmkq7ITNTjw9sgsBzcbU3oU8=; b=oHzz5xXx7wpSMlFWwXBcirsMY/0qre8ERdacc8QKi14NKrvP7dolydjb2mrk8Udkz2r+sz TwbiZxoO8SloAPpJ1I1s6N043kSe5QQJeao4CCQMZSZYL/RS/c1AuHvN/4VH7mkPuCBik6 ERbCrhocw+1oall4V38deMUH1+zvXaw= ARC-Authentication-Results: i=1; imf28.hostedemail.com; dkim=none; dmarc=none; spf=neutral (imf28.hostedemail.com: 66.220.144.178 is neither permitted nor denied by domain of shr@devkernel.io) smtp.mailfrom=shr@devkernel.io ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1665450072; a=rsa-sha256; cv=none; b=Pk0IJXcjUblrrp0nwQltB0gMJH45PUtVWHjP1qnv3h8iwysLl09IN/KKzcY/4BpSKS+GNv CntLjXQJLCDiVUYgpt/ogeMWMVzL5sQvScD55POzhVYHfxSzXSGPXAfGAFefWeEXQF9I2Q GW4WCKGQ6dKlmHe7CeFfFrWKqL05Ea0= Authentication-Results: imf28.hostedemail.com; dkim=none; dmarc=none; spf=neutral (imf28.hostedemail.com: 66.220.144.178 is neither permitted nor denied by domain of shr@devkernel.io) smtp.mailfrom=shr@devkernel.io X-Stat-Signature: 4hymjbinezu5rz3t4odpwowgkoxk17r7 X-Rspamd-Queue-Id: 8358BC0032 X-Rspam-User: X-Rspamd-Server: rspam06 X-HE-Tag: 1665450072-212393 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000002, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: At meta network block devices (nbd) are used to implement remote block st= orage. In testing and during production it has been observed that these network block devic= es can consume a huge portion of the dirty writeback and writeback can take a considerab= le time. To give stricter limits, I'm proposing the following changes and new sysf= s knobs: 1) strictlimit knob Currently the max_ratio knob exists to limit the dirty_memory. However = this knob only applies once (dirty_ratio + dirty_background_ratio) / 2 has been r= eached. With the BDI_CAP_STRICTLIMIT flag, the max_ratio can be applied without= reaching that limit. This change exposes that knob. This knob can also be useful for NFS, fuse filesystems and USB devices. 2) Part of 10000 internal calculation The max_ratio is based on percentage. With the current machine sizes pe= rcentage values can be very high (1% of a 256GB main memory is already 2.5GB). T= his change uses part of 10000 instead of percentages for the internal calculations= . 3) Introduce two new knobs: min_bytes and max_bytes. Currently all calculations are based on ratio, but for a user it often = more convenient to specify a limit in bytes. The new knobs will not store by= tes values, instead they will translate the byte value to a corresponding ratio. As= the internal values are now part of 10000, the ratio is closer to the specified valu= e. However the value should be more seen as an approximation as it can fluctuate o= ver time. Stefan Roesch (14): mm: add bdi_set_strict_limit() function mm: Add new knob /sys/class/bdi//strict_limit mm: document new /sys/class/bdi//strict_limit knob mm: Use part per 10000 for bdi ratios. mm: add bdi_get_max_bytes() function mm: split off __bdi_set_max_ratio() function mm: add bdi_set_max_bytes() function. mm: Add new knob /sys/class/bdi//max_bytes mm: document new /sys/class/bdi//max_bytes knob mm: add bdi_get_min_bytes() function. mm: split off __bdi_set_min_ratio() function mm: add bdi_set_min_bytes() function mm: add new /sys/class/bdi//min_bytes knob mm: document new /sys/class/bdi//min_bytes knob Documentation/ABI/testing/sysfs-class-bdi | 40 +++++++ include/linux/backing-dev.h | 8 ++ mm/backing-dev.c | 93 +++++++++++++++- mm/page-writeback.c | 126 ++++++++++++++++++++-- 4 files changed, 253 insertions(+), 14 deletions(-) base-commit: e2302539dd4f1c62d96651c07ddb05aa2461d29c --=20 2.30.2