From patchwork Fri Nov 5 20:47:57 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Andrew Morton X-Patchwork-Id: 12605903 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 mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 1E102C433F5 for ; Fri, 5 Nov 2021 20:48:01 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id B48A760FBF for ; Fri, 5 Nov 2021 20:48:00 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org B48A760FBF Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=linux-foundation.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=kvack.org Received: by kanga.kvack.org (Postfix) id 4EF229400F5; Fri, 5 Nov 2021 16:48:00 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 49F629400EF; Fri, 5 Nov 2021 16:48:00 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 367689400F5; Fri, 5 Nov 2021 16:48:00 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0138.hostedemail.com [216.40.44.138]) by kanga.kvack.org (Postfix) with ESMTP id 23F609400EF for ; Fri, 5 Nov 2021 16:48:00 -0400 (EDT) Received: from smtpin26.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay03.hostedemail.com (Postfix) with ESMTP id D5C138249980 for ; Fri, 5 Nov 2021 20:47:59 +0000 (UTC) X-FDA: 78776063478.26.4084374 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by imf11.hostedemail.com (Postfix) with ESMTP id 75138F0000B0 for ; Fri, 5 Nov 2021 20:47:59 +0000 (UTC) Received: by mail.kernel.org (Postfix) with ESMTPSA id 390F560E94; Fri, 5 Nov 2021 20:47:58 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1636145278; bh=phuAd4uflVdFoL/s3a/K4ACiVtKmm+RIavgG7d0c89Y=; h=Date:From:To:Subject:In-Reply-To:From; b=E/pMiYGnNGfeBcsN2d6XMQZNMUgZ/yefkCvay26tLHK/y7oSOzuuPLfr2DUsc96rd HTde148DrWriCfLglU0L1s2GjFFUGJTCtz4nvsboOocTahFvzk4HLRvydWA7LDiyad HvM0fdgQ/vq1Kt/7FCgu7exmLsCtyKgQblco8Tuk= Date: Fri, 05 Nov 2021 13:47:57 -0700 From: Andrew Morton To: akpm@linux-foundation.org, amit@kernel.org, benh@kernel.crashing.org, corbet@lwn.net, david@redhat.com, dwmw@amazon.com, elver@google.com, foersleo@amazon.de, gthelen@google.com, Jonathan.Cameron@huawei.com, linux-mm@kvack.org, markubo@amazon.de, mm-commits@vger.kernel.org, rientjes@google.com, shakeelb@google.com, shuah@kernel.org, sj@kernel.org, torvalds@linux-foundation.org, yangyingliang@huawei.com Subject: [patch 252/262] mm/damon: introduce DAMON-based Reclamation (DAMON_RECLAIM) Message-ID: <20211105204757.6AUMFKAtz%akpm@linux-foundation.org> In-Reply-To: <20211105133408.cccbb98b71a77d5e8430aba1@linux-foundation.org> User-Agent: s-nail v14.8.16 X-Rspamd-Server: rspam01 X-Rspamd-Queue-Id: 75138F0000B0 X-Stat-Signature: 6iojs4zcywxfq6mwut76akxsickdjeyo Authentication-Results: imf11.hostedemail.com; dkim=pass header.d=linux-foundation.org header.s=korg header.b="E/pMiYGn"; dmarc=none; spf=pass (imf11.hostedemail.com: domain of akpm@linux-foundation.org designates 198.145.29.99 as permitted sender) smtp.mailfrom=akpm@linux-foundation.org X-HE-Tag: 1636145279-125823 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: From: SeongJae Park Subject: mm/damon: introduce DAMON-based Reclamation (DAMON_RECLAIM) This commit implements a new kernel subsystem that finds cold memory regions using DAMON and reclaims those immediately. It is intended to be used as proactive lightweigh reclamation logic for light memory pressure. For heavy memory pressure, it could be inactivated and fall back to the traditional page-scanning based reclamation. It's implemented on top of DAMON framework to use the DAMON-based Operation Schemes (DAMOS) feature. It utilizes all the DAMOS features including speed limit, prioritization, and watermarks. It could be enabled and tuned in boot time via the kernel boot parameter, and in run time via its module parameters ('/sys/module/damon_reclaim/parameters/') interface. [yangyingliang@huawei.com: fix error return code in damon_reclaim_turn()] Link: https://lkml.kernel.org/r/20211025124500.2758060-1-yangyingliang@huawei.com Link: https://lkml.kernel.org/r/20211019150731.16699-15-sj@kernel.org Signed-off-by: SeongJae Park Signed-off-by: Yang Yingliang Cc: Amit Shah Cc: Benjamin Herrenschmidt Cc: David Hildenbrand Cc: David Rientjes Cc: David Woodhouse Cc: Greg Thelen Cc: Jonathan Cameron Cc: Jonathan Corbet Cc: Leonard Foerster Cc: Marco Elver Cc: Markus Boehme Cc: Shakeel Butt Cc: Shuah Khan Signed-off-by: Andrew Morton --- mm/damon/Kconfig | 12 + mm/damon/Makefile | 1 mm/damon/reclaim.c | 356 +++++++++++++++++++++++++++++++++++++++++++ 3 files changed, 369 insertions(+) --- a/mm/damon/Kconfig~mm-damon-introduce-damon-based-reclamation-damon_reclaim +++ a/mm/damon/Kconfig @@ -73,4 +73,16 @@ config DAMON_DBGFS_KUNIT_TEST If unsure, say N. +config DAMON_RECLAIM + bool "Build DAMON-based reclaim (DAMON_RECLAIM)" + depends on DAMON_PADDR + help + This builds the DAMON-based reclamation subsystem. It finds pages + that not accessed for a long time (cold) using DAMON and reclaim + those. + + This is suggested to be used as a proactive and lightweight + reclamation under light memory pressure, while the traditional page + scanning-based reclamation is used for heavy pressure. + endmenu --- a/mm/damon/Makefile~mm-damon-introduce-damon-based-reclamation-damon_reclaim +++ a/mm/damon/Makefile @@ -4,3 +4,4 @@ obj-$(CONFIG_DAMON) := core.o obj-$(CONFIG_DAMON_VADDR) += prmtv-common.o vaddr.o obj-$(CONFIG_DAMON_PADDR) += prmtv-common.o paddr.o obj-$(CONFIG_DAMON_DBGFS) += dbgfs.o +obj-$(CONFIG_DAMON_RECLAIM) += reclaim.o --- /dev/null +++ a/mm/damon/reclaim.c @@ -0,0 +1,356 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * DAMON-based page reclamation + * + * Author: SeongJae Park + */ + +#define pr_fmt(fmt) "damon-reclaim: " fmt + +#include +#include +#include +#include +#include + +#ifdef MODULE_PARAM_PREFIX +#undef MODULE_PARAM_PREFIX +#endif +#define MODULE_PARAM_PREFIX "damon_reclaim." + +/* + * Enable or disable DAMON_RECLAIM. + * + * You can enable DAMON_RCLAIM by setting the value of this parameter as ``Y``. + * Setting it as ``N`` disables DAMON_RECLAIM. Note that DAMON_RECLAIM could + * do no real monitoring and reclamation due to the watermarks-based activation + * condition. Refer to below descriptions for the watermarks parameter for + * this. + */ +static bool enabled __read_mostly; +module_param(enabled, bool, 0600); + +/* + * Time threshold for cold memory regions identification in microseconds. + * + * If a memory region is not accessed for this or longer time, DAMON_RECLAIM + * identifies the region as cold, and reclaims. 120 seconds by default. + */ +static unsigned long min_age __read_mostly = 120000000; +module_param(min_age, ulong, 0600); + +/* + * Limit of time for trying the reclamation in milliseconds. + * + * DAMON_RECLAIM tries to use only up to this time within a time window + * (quota_reset_interval_ms) for trying reclamation of cold pages. This can be + * used for limiting CPU consumption of DAMON_RECLAIM. If the value is zero, + * the limit is disabled. + * + * 10 ms by default. + */ +static unsigned long quota_ms __read_mostly = 10; +module_param(quota_ms, ulong, 0600); + +/* + * Limit of size of memory for the reclamation in bytes. + * + * DAMON_RECLAIM charges amount of memory which it tried to reclaim within a + * time window (quota_reset_interval_ms) and makes no more than this limit is + * tried. This can be used for limiting consumption of CPU and IO. If this + * value is zero, the limit is disabled. + * + * 128 MiB by default. + */ +static unsigned long quota_sz __read_mostly = 128 * 1024 * 1024; +module_param(quota_sz, ulong, 0600); + +/* + * The time/size quota charge reset interval in milliseconds. + * + * The charge reset interval for the quota of time (quota_ms) and size + * (quota_sz). That is, DAMON_RECLAIM does not try reclamation for more than + * quota_ms milliseconds or quota_sz bytes within quota_reset_interval_ms + * milliseconds. + * + * 1 second by default. + */ +static unsigned long quota_reset_interval_ms __read_mostly = 1000; +module_param(quota_reset_interval_ms, ulong, 0600); + +/* + * The watermarks check time interval in microseconds. + * + * Minimal time to wait before checking the watermarks, when DAMON_RECLAIM is + * enabled but inactive due to its watermarks rule. 5 seconds by default. + */ +static unsigned long wmarks_interval __read_mostly = 5000000; +module_param(wmarks_interval, ulong, 0600); + +/* + * Free memory rate (per thousand) for the high watermark. + * + * If free memory of the system in bytes per thousand bytes is higher than + * this, DAMON_RECLAIM becomes inactive, so it does nothing but periodically + * checks the watermarks. 500 (50%) by default. + */ +static unsigned long wmarks_high __read_mostly = 500; +module_param(wmarks_high, ulong, 0600); + +/* + * Free memory rate (per thousand) for the middle watermark. + * + * If free memory of the system in bytes per thousand bytes is between this and + * the low watermark, DAMON_RECLAIM becomes active, so starts the monitoring + * and the reclaiming. 400 (40%) by default. + */ +static unsigned long wmarks_mid __read_mostly = 400; +module_param(wmarks_mid, ulong, 0600); + +/* + * Free memory rate (per thousand) for the low watermark. + * + * If free memory of the system in bytes per thousand bytes is lower than this, + * DAMON_RECLAIM becomes inactive, so it does nothing but periodically checks + * the watermarks. In the case, the system falls back to the LRU-based page + * granularity reclamation logic. 200 (20%) by default. + */ +static unsigned long wmarks_low __read_mostly = 200; +module_param(wmarks_low, ulong, 0600); + +/* + * Sampling interval for the monitoring in microseconds. + * + * The sampling interval of DAMON for the cold memory monitoring. Please refer + * to the DAMON documentation for more detail. 5 ms by default. + */ +static unsigned long sample_interval __read_mostly = 5000; +module_param(sample_interval, ulong, 0600); + +/* + * Aggregation interval for the monitoring in microseconds. + * + * The aggregation interval of DAMON for the cold memory monitoring. Please + * refer to the DAMON documentation for more detail. 100 ms by default. + */ +static unsigned long aggr_interval __read_mostly = 100000; +module_param(aggr_interval, ulong, 0600); + +/* + * Minimum number of monitoring regions. + * + * The minimal number of monitoring regions of DAMON for the cold memory + * monitoring. This can be used to set lower-bound of the monitoring quality. + * But, setting this too high could result in increased monitoring overhead. + * Please refer to the DAMON documentation for more detail. 10 by default. + */ +static unsigned long min_nr_regions __read_mostly = 10; +module_param(min_nr_regions, ulong, 0600); + +/* + * Maximum number of monitoring regions. + * + * The maximum number of monitoring regions of DAMON for the cold memory + * monitoring. This can be used to set upper-bound of the monitoring overhead. + * However, setting this too low could result in bad monitoring quality. + * Please refer to the DAMON documentation for more detail. 1000 by default. + */ +static unsigned long max_nr_regions __read_mostly = 1000; +module_param(max_nr_regions, ulong, 0600); + +/* + * Start of the target memory region in physical address. + * + * The start physical address of memory region that DAMON_RECLAIM will do work + * against. By default, biggest System RAM is used as the region. + */ +static unsigned long monitor_region_start __read_mostly; +module_param(monitor_region_start, ulong, 0600); + +/* + * End of the target memory region in physical address. + * + * The end physical address of memory region that DAMON_RECLAIM will do work + * against. By default, biggest System RAM is used as the region. + */ +static unsigned long monitor_region_end __read_mostly; +module_param(monitor_region_end, ulong, 0600); + +/* + * PID of the DAMON thread + * + * If DAMON_RECLAIM is enabled, this becomes the PID of the worker thread. + * Else, -1. + */ +static int kdamond_pid __read_mostly = -1; +module_param(kdamond_pid, int, 0400); + +static struct damon_ctx *ctx; +static struct damon_target *target; + +struct damon_reclaim_ram_walk_arg { + unsigned long start; + unsigned long end; +}; + +static int walk_system_ram(struct resource *res, void *arg) +{ + struct damon_reclaim_ram_walk_arg *a = arg; + + if (a->end - a->start < res->end - res->start) { + a->start = res->start; + a->end = res->end; + } + return 0; +} + +/* + * Find biggest 'System RAM' resource and store its start and end address in + * @start and @end, respectively. If no System RAM is found, returns false. + */ +static bool get_monitoring_region(unsigned long *start, unsigned long *end) +{ + struct damon_reclaim_ram_walk_arg arg = {}; + + walk_system_ram_res(0, ULONG_MAX, &arg, walk_system_ram); + if (arg.end <= arg.start) + return false; + + *start = arg.start; + *end = arg.end; + return true; +} + +static struct damos *damon_reclaim_new_scheme(void) +{ + struct damos_watermarks wmarks = { + .metric = DAMOS_WMARK_FREE_MEM_RATE, + .interval = wmarks_interval, + .high = wmarks_high, + .mid = wmarks_mid, + .low = wmarks_low, + }; + struct damos_quota quota = { + /* + * Do not try reclamation for more than quota_ms milliseconds + * or quota_sz bytes within quota_reset_interval_ms. + */ + .ms = quota_ms, + .sz = quota_sz, + .reset_interval = quota_reset_interval_ms, + /* Within the quota, page out older regions first. */ + .weight_sz = 0, + .weight_nr_accesses = 0, + .weight_age = 1 + }; + struct damos *scheme = damon_new_scheme( + /* Find regions having PAGE_SIZE or larger size */ + PAGE_SIZE, ULONG_MAX, + /* and not accessed at all */ + 0, 0, + /* for min_age or more micro-seconds, and */ + min_age / aggr_interval, UINT_MAX, + /* page out those, as soon as found */ + DAMOS_PAGEOUT, + /* under the quota. */ + "a, + /* (De)activate this according to the watermarks. */ + &wmarks); + + return scheme; +} + +static int damon_reclaim_turn(bool on) +{ + struct damon_region *region; + struct damos *scheme; + int err; + + if (!on) { + err = damon_stop(&ctx, 1); + if (!err) + kdamond_pid = -1; + return err; + } + + err = damon_set_attrs(ctx, sample_interval, aggr_interval, 0, + min_nr_regions, max_nr_regions); + if (err) + return err; + + if (monitor_region_start > monitor_region_end) + return -EINVAL; + if (!monitor_region_start && !monitor_region_end && + !get_monitoring_region(&monitor_region_start, + &monitor_region_end)) + return -EINVAL; + /* DAMON will free this on its own when finish monitoring */ + region = damon_new_region(monitor_region_start, monitor_region_end); + if (!region) + return -ENOMEM; + damon_add_region(region, target); + + /* Will be freed by 'damon_set_schemes()' below */ + scheme = damon_reclaim_new_scheme(); + if (!scheme) { + err = -ENOMEM; + goto free_region_out; + } + err = damon_set_schemes(ctx, &scheme, 1); + if (err) + goto free_scheme_out; + + err = damon_start(&ctx, 1); + if (!err) { + kdamond_pid = ctx->kdamond->pid; + return 0; + } + +free_scheme_out: + damon_destroy_scheme(scheme); +free_region_out: + damon_destroy_region(region, target); + return err; +} + +#define ENABLE_CHECK_INTERVAL_MS 1000 +static struct delayed_work damon_reclaim_timer; +static void damon_reclaim_timer_fn(struct work_struct *work) +{ + static bool last_enabled; + bool now_enabled; + + now_enabled = enabled; + if (last_enabled != now_enabled) { + if (!damon_reclaim_turn(now_enabled)) + last_enabled = now_enabled; + else + enabled = last_enabled; + } + + schedule_delayed_work(&damon_reclaim_timer, + msecs_to_jiffies(ENABLE_CHECK_INTERVAL_MS)); +} +static DECLARE_DELAYED_WORK(damon_reclaim_timer, damon_reclaim_timer_fn); + +static int __init damon_reclaim_init(void) +{ + ctx = damon_new_ctx(); + if (!ctx) + return -ENOMEM; + + damon_pa_set_primitives(ctx); + + /* 4242 means nothing but fun */ + target = damon_new_target(4242); + if (!target) { + damon_destroy_ctx(ctx); + return -ENOMEM; + } + damon_add_target(ctx, target); + + schedule_delayed_work(&damon_reclaim_timer, 0); + return 0; +} + +module_init(damon_reclaim_init);