From patchwork Sat Nov 19 00:51:55 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Stefan Roesch X-Patchwork-Id: 13049434 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 84D8CC433FE for ; Sat, 19 Nov 2022 00:52:33 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 0773C6B0072; Fri, 18 Nov 2022 19:52:33 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 026CA6B0073; Fri, 18 Nov 2022 19:52:32 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id E09FC6B0075; Fri, 18 Nov 2022 19:52:32 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0011.hostedemail.com [216.40.44.11]) by kanga.kvack.org (Postfix) with ESMTP id CCC886B0072 for ; Fri, 18 Nov 2022 19:52:32 -0500 (EST) Received: from smtpin20.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay07.hostedemail.com (Postfix) with ESMTP id 9AC0716091E for ; Sat, 19 Nov 2022 00:52:32 +0000 (UTC) X-FDA: 80148366144.20.7DA98F7 Received: from 66-220-144-178.mail-mxout.facebook.com (66-220-144-178.mail-mxout.facebook.com [66.220.144.178]) by imf23.hostedemail.com (Postfix) with ESMTP id 3E376140004 for ; Sat, 19 Nov 2022 00:52:32 +0000 (UTC) Received: by dev0134.prn3.facebook.com (Postfix, from userid 425415) id 4B3E519380C6; Fri, 18 Nov 2022 16:52:18 -0800 (PST) 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, akpm@linux-foundation.org Subject: [RFC PATCH v4 00/20] mm/block: add bdi sysfs knobs Date: Fri, 18 Nov 2022 16:51:55 -0800 Message-Id: <20221119005215.3052436-1-shr@devkernel.io> X-Mailer: git-send-email 2.30.2 MIME-Version: 1.0 ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1668819152; a=rsa-sha256; cv=none; b=TpwwhLa4wC01RksHtarjGsEf9/sJtNx0zIoEogd9/zpEMfhqyR8A6mLRRLzALIb1+bZR/8 mRQsY1yoyRIIOZYdHDapG/ZMHLme+LwE+21JgRJ4sBJg5t85D6ajq40hmZK2nICjnWQD4A OTjecVY0RR7LcnPAfcGAFqRwVoRdw/E= ARC-Authentication-Results: i=1; imf23.hostedemail.com; dkim=none; dmarc=none; spf=neutral (imf23.hostedemail.com: 66.220.144.178 is neither permitted nor denied by domain of shr@devkernel.io) smtp.mailfrom=shr@devkernel.io ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1668819152; 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=FlgL9OEwqW7dHj1+R9ybC3LWviThKAGmdwWm01I/LNs=; b=QxJNldNGZG3xc0x3j9DXhsIcO8cPDLRv/3TB2JGsPQINsJA5U7HAno7MdKrOII7TTvRclU 3x6/vxuR6ZJgbzhN2h/1mwwr3v0mwQlGlzEMHl+7gFjlCOBvYAzGapO1hFkZOoYfV0pEvt uHqhxT3V+I9eV6eBgb6HPBxvAacYHuE= X-Stat-Signature: 9bjwyn8dzcjai4do4ejyrg1an57r597z X-Rspamd-Queue-Id: 3E376140004 Authentication-Results: imf23.hostedemail.com; dkim=none; dmarc=none; spf=neutral (imf23.hostedemail.com: 66.220.144.178 is neither permitted nor denied by domain of shr@devkernel.io) smtp.mailfrom=shr@devkernel.io X-Rspamd-Server: rspam04 X-Rspam-User: X-HE-Tag: 1668819152-87778 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, 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 storage. In testing and during production it has been observed that these network block devices can consume a huge portion of the dirty writeback cache and writeback can take a considerable time. To be able to give stricter limits, I'm proposing the following changes: 1) introduce 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 reached. 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) Use part of 1000000 internal calculation The max_ratio is based on percentage. With the current machine sizes percentage values can be very high (1% of a 256GB main memory is already 2.5GB). This change uses part of 1000000 instead of percentages for the internal calculations. 3) Introduce two new sysfs 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 bytes values, instead they will translate the byte value to a corresponding ratio. As the internal values are now part of 1000, the ratio is closer to the specified value. However the value should be more seen as an approximation as it can fluctuate over time. 3) Introduce two new sysfs knobs: min_ratio_fine and max_ratio_fine. The granularity for the existing sysfs bdi knobs min_ratio and max_ratio is based on percentage values. The new sysfs bdi knobs min_ratio_fine and max_ratio_fine allow to specify the ratio as part of 1 million. Changes: V4: - Introduced two new sysfs knobs min_ratio_fine and max_ratio_fine to allow setting ratios with smaller granularity - Refreshed to 6.1-rc5 - removed bdi_set_strict_limit export - removed bdi_get_max_bytes export - removed bdi_set_max_bytes export - change granularity to part of 1000000 - changed function signature of bdi_get_max_bytes() to return u64 - Fixed commit message of "mm: split off __bdi_set_max_ratio() function" - changed check in bdi_check_pages_limit() V3: - change signature of function bdi_ratio_from_pages to take an unsigned long parameter - use div64_u64 function for division to support 32 bit platforms - Refreshed to 6.1-rc2 V2: - Refreshed to 6.1-rc1 - Use part of 1000, instead of part of 10000 - Reformat cover letter Stefan Roesch (20): mm: add bdi_set_strict_limit() function mm: add knob /sys/class/bdi//strict_limit mm: document /sys/class/bdi//strict_limit knob mm: use part per 1000000 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 knob /sys/class/bdi//max_bytes mm: document /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 /sys/class/bdi//min_bytes knob mm: document /sys/class/bdi//min_bytes knob mm: add bdi_set_max_ratio_no_scale() function mm: add /sys/class/bdi//max_ratio_fine knob mm: document /sys/class/bdi//max_ratio_fine knob mm: add bdi_set_min_ratio_no_scale() function mm: add /sys/class/bdi//min_ratio_fine knob mm: document /sys/class/bdi//min_ratio_fine knob Documentation/ABI/testing/sysfs-class-bdi | 68 +++++++++++ include/linux/backing-dev.h | 10 ++ mm/backing-dev.c | 133 +++++++++++++++++++++- mm/page-writeback.c | 130 +++++++++++++++++++-- 4 files changed, 329 insertions(+), 12 deletions(-) base-commit: ab290eaddc4c41b237b9a366fa6a5527be890b84