From patchwork Tue Oct 11 01:00:34 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Stefan Roesch X-Patchwork-Id: 13003478 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 A4067C433FE for ; Tue, 11 Oct 2022 01:01:20 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 34DDD6B0078; Mon, 10 Oct 2022 21:01:20 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 326006B0075; Mon, 10 Oct 2022 21:01:20 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 1532F8E0001; Mon, 10 Oct 2022 21:01:20 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0014.hostedemail.com [216.40.44.14]) by kanga.kvack.org (Postfix) with ESMTP id 00B326B0075 for ; Mon, 10 Oct 2022 21:01:19 -0400 (EDT) Received: from smtpin11.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay01.hostedemail.com (Postfix) with ESMTP id CDD621C6264 for ; Tue, 11 Oct 2022 01:01:19 +0000 (UTC) X-FDA: 80006865078.11.39574F0 Received: from 66-220-144-178.mail-mxout.facebook.com (66-220-144-178.mail-mxout.facebook.com [66.220.144.178]) by imf12.hostedemail.com (Postfix) with ESMTP id 623B440020 for ; Tue, 11 Oct 2022 01:01:19 +0000 (UTC) Received: by dev1180.prn1.facebook.com (Postfix, from userid 425415) id 03A3A34BDDD6; Mon, 10 Oct 2022 18:01:06 -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 04/14] mm: Use part per 10000 for bdi ratios. Date: Mon, 10 Oct 2022 18:00:34 -0700 Message-Id: <20221011010044.851537-5-shr@devkernel.io> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20221011010044.851537-1-shr@devkernel.io> References: <20221011010044.851537-1-shr@devkernel.io> MIME-Version: 1.0 ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1665450079; a=rsa-sha256; cv=none; b=Bo4Or91kLpGwAyAiKPHyMUIrylkpFwZ/d94bkOzlzOD3wOI7z7oTE/L9WUHeQTFqlK20NC HldquRW6k+gz2ZBhg0vEzKrj4EaFKWC5OVKrxI9/vnvId8eL+1wZ/LjglF3VLoJ1rLyDd7 x1d8k07YeS2oQk06XbH3n6XYxSb8bn8= ARC-Authentication-Results: i=1; imf12.hostedemail.com; dkim=none; spf=neutral (imf12.hostedemail.com: 66.220.144.178 is neither permitted nor denied by domain of shr@devkernel.io) smtp.mailfrom=shr@devkernel.io; dmarc=none ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1665450079; 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:in-reply-to:references:references; bh=W8IYwB333sjky2c2+5pyHNPQ63AnO4y3dd6FNlJ0stI=; b=Px4h0Fm/cmlkHrH6/wnh+0xNfzKa331locjDzWk6QCrcUPhdsllf0WJ43RBwawzj5kBfgt wjmYDDKerUSwLtqLEDXGYe42whA+oIYHdR1WNrx7TJ5cZ/wUlk7c3tG4q3yTsSekNjkXvp LWZeKEzw/STKA4ZD7nxqzYttDvqBwTU= Authentication-Results: imf12.hostedemail.com; dkim=none; spf=neutral (imf12.hostedemail.com: 66.220.144.178 is neither permitted nor denied by domain of shr@devkernel.io) smtp.mailfrom=shr@devkernel.io; dmarc=none X-Stat-Signature: cs8doa6os34nsat7a1a5rfzta8szu51n X-Rspamd-Queue-Id: 623B440020 X-Rspam-User: X-Rspamd-Server: rspam05 X-HE-Tag: 1665450079-105724 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: To get finer granularity for ratio calculations use part per 10000 instead of percentiles. This is especially important if we want to automatically convert byte values to ratios. Otherwise the values that are actually used can be quite different. This is also important for machines with more main memory (1% of 256GB is already 2.5GB). Signed-off-by: Stefan Roesch --- include/linux/backing-dev.h | 3 +++ mm/backing-dev.c | 6 +++--- mm/page-writeback.c | 15 +++++++++------ 3 files changed, 15 insertions(+), 9 deletions(-) diff --git a/include/linux/backing-dev.h b/include/linux/backing-dev.h index 9c984ffc8a0a..f698befa76a0 100644 --- a/include/linux/backing-dev.h +++ b/include/linux/backing-dev.h @@ -102,6 +102,9 @@ static inline unsigned long wb_stat_error(void) #endif } +/* BDI ratio is expressed as part per 10000 for finer granularity. */ +#define BDI_RATIO_SCALE 100 + int bdi_set_min_ratio(struct backing_dev_info *bdi, unsigned int min_ratio); int bdi_set_max_ratio(struct backing_dev_info *bdi, unsigned int max_ratio); int bdi_set_strict_limit(struct backing_dev_info *bdi, unsigned int strict_limit); diff --git a/mm/backing-dev.c b/mm/backing-dev.c index f9aaa14ad98f..e64bc49561b1 100644 --- a/mm/backing-dev.c +++ b/mm/backing-dev.c @@ -178,7 +178,7 @@ static ssize_t min_ratio_store(struct device *dev, return ret; } -BDI_SHOW(min_ratio, bdi->min_ratio) +BDI_SHOW(min_ratio, bdi->min_ratio / BDI_RATIO_SCALE) static ssize_t max_ratio_store(struct device *dev, struct device_attribute *attr, const char *buf, size_t count) @@ -197,7 +197,7 @@ static ssize_t max_ratio_store(struct device *dev, return ret; } -BDI_SHOW(max_ratio, bdi->max_ratio) +BDI_SHOW(max_ratio, bdi->max_ratio / BDI_RATIO_SCALE) static ssize_t stable_pages_required_show(struct device *dev, struct device_attribute *attr, @@ -811,7 +811,7 @@ int bdi_init(struct backing_dev_info *bdi) kref_init(&bdi->refcnt); bdi->min_ratio = 0; - bdi->max_ratio = 100; + bdi->max_ratio = 100 * BDI_RATIO_SCALE; bdi->max_prop_frac = FPROP_FRAC_BASE; INIT_LIST_HEAD(&bdi->bdi_list); INIT_LIST_HEAD(&bdi->wb_list); diff --git a/mm/page-writeback.c b/mm/page-writeback.c index e22aae0ecacd..4d5383d4da45 100644 --- a/mm/page-writeback.c +++ b/mm/page-writeback.c @@ -197,7 +197,7 @@ static void wb_min_max_ratio(struct bdi_writeback *wb, min *= this_bw; min = div64_ul(min, tot_bw); } - if (max < 100) { + if (max < 100 * BDI_RATIO_SCALE) { max *= this_bw; max = div64_ul(max, tot_bw); } @@ -655,6 +655,8 @@ int bdi_set_min_ratio(struct backing_dev_info *bdi, unsigned int min_ratio) unsigned int delta; int ret = 0; + min_ratio *= BDI_RATIO_SCALE; + spin_lock_bh(&bdi_lock); if (min_ratio > bdi->max_ratio) { ret = -EINVAL; @@ -665,7 +667,7 @@ int bdi_set_min_ratio(struct backing_dev_info *bdi, unsigned int min_ratio) bdi->min_ratio = min_ratio; } else { delta = min_ratio - bdi->min_ratio; - if (bdi_min_ratio + delta < 100) { + if (bdi_min_ratio + delta < 100 * BDI_RATIO_SCALE) { bdi_min_ratio += delta; bdi->min_ratio = min_ratio; } else { @@ -684,6 +686,7 @@ int bdi_set_max_ratio(struct backing_dev_info *bdi, unsigned max_ratio) if (max_ratio > 100) return -EINVAL; + max_ratio *= BDI_RATIO_SCALE; spin_lock_bh(&bdi_lock); if (bdi->min_ratio > max_ratio) { @@ -776,15 +779,15 @@ static unsigned long __wb_calc_thresh(struct dirty_throttle_control *dtc) fprop_fraction_percpu(&dom->completions, dtc->wb_completions, &numerator, &denominator); - wb_thresh = (thresh * (100 - bdi_min_ratio)) / 100; + wb_thresh = (thresh * (100 * BDI_RATIO_SCALE - bdi_min_ratio)) / (100 * BDI_RATIO_SCALE); wb_thresh *= numerator; wb_thresh = div64_ul(wb_thresh, denominator); wb_min_max_ratio(dtc->wb, &wb_min_ratio, &wb_max_ratio); - wb_thresh += (thresh * wb_min_ratio) / 100; - if (wb_thresh > (thresh * wb_max_ratio) / 100) - wb_thresh = thresh * wb_max_ratio / 100; + wb_thresh += (thresh * wb_min_ratio) / (100 * BDI_RATIO_SCALE); + if (wb_thresh > (thresh * wb_max_ratio) / (100 * BDI_RATIO_SCALE)) + wb_thresh = thresh * wb_max_ratio / (100 * BDI_RATIO_SCALE); return wb_thresh; }