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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 02526C433FE for ; Sat, 19 Nov 2022 01:44:18 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232820AbiKSBoQ (ORCPT ); Fri, 18 Nov 2022 20:44:16 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:43028 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232194AbiKSBn6 (ORCPT ); Fri, 18 Nov 2022 20:43:58 -0500 Received: from 66-220-144-178.mail-mxout.facebook.com (66-220-144-178.mail-mxout.facebook.com [66.220.144.178]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 24917BE274 for ; Fri, 18 Nov 2022 16:57:37 -0800 (PST) Received: by dev0134.prn3.facebook.com (Postfix, from userid 425415) id 5DF8C19380D0; 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 05/20] mm: add bdi_get_max_bytes() function Date: Fri, 18 Nov 2022 16:52:00 -0800 Message-Id: <20221119005215.3052436-6-shr@devkernel.io> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20221119005215.3052436-1-shr@devkernel.io> References: <20221119005215.3052436-1-shr@devkernel.io> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org This adds a function to return the specified value for max_bytes. It converts the stored max_ratio of the bdi to the corresponding bytes value. It introduces the bdi_get_bytes helper function to do the conversion. This is an approximation as it is based on the value that is returned by global_dirty_limits(), which can change. The helper function will also be used by the min_bytes bdi knob. Signed-off-by: Stefan Roesch --- include/linux/backing-dev.h | 1 + mm/page-writeback.c | 17 +++++++++++++++++ 2 files changed, 18 insertions(+) diff --git a/include/linux/backing-dev.h b/include/linux/backing-dev.h index 1b50c028e5ad..473686c32775 100644 --- a/include/linux/backing-dev.h +++ b/include/linux/backing-dev.h @@ -105,6 +105,7 @@ static inline unsigned long wb_stat_error(void) /* BDI ratio is expressed as part per 1000000 for finer granularity. */ #define BDI_RATIO_SCALE 10000 =20 +u64 bdi_get_max_bytes(struct backing_dev_info *bdi); int bdi_set_min_ratio(struct backing_dev_info *bdi, unsigned int min_rat= io); int bdi_set_max_ratio(struct backing_dev_info *bdi, unsigned int max_rat= io); int bdi_set_strict_limit(struct backing_dev_info *bdi, unsigned int stri= ct_limit); diff --git a/mm/page-writeback.c b/mm/page-writeback.c index dd98b2654302..719404e0d03d 100644 --- a/mm/page-writeback.c +++ b/mm/page-writeback.c @@ -650,6 +650,18 @@ void wb_domain_exit(struct wb_domain *dom) */ static unsigned int bdi_min_ratio; =20 +static u64 bdi_get_bytes(unsigned int ratio) +{ + unsigned long background_thresh; + unsigned long dirty_thresh; + u64 bytes; + + global_dirty_limits(&background_thresh, &dirty_thresh); + bytes =3D (dirty_thresh * PAGE_SIZE * ratio) / BDI_RATIO_SCALE / 100; + + return bytes; +} + int bdi_set_min_ratio(struct backing_dev_info *bdi, unsigned int min_rat= io) { unsigned int delta; @@ -701,6 +713,11 @@ int bdi_set_max_ratio(struct backing_dev_info *bdi, = unsigned max_ratio) } EXPORT_SYMBOL(bdi_set_max_ratio); =20 +u64 bdi_get_max_bytes(struct backing_dev_info *bdi) +{ + return bdi_get_bytes(bdi->max_ratio); +} + int bdi_set_strict_limit(struct backing_dev_info *bdi, unsigned int stri= ct_limit) { if (strict_limit > 1) --=20 2.30.2