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[23.128.96.18]) by mx.google.com with ESMTP id gz25si73608ejc.507.2021.06.17.00.32.14; Thu, 17 Jun 2021 00:32:37 -0700 (PDT) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18; Authentication-Results: mx.google.com; dkim=pass header.i=@mg.codeaurora.org header.s=smtp header.b=U4ydUD+y; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230075AbhFQHcv (ORCPT + 99 others); Thu, 17 Jun 2021 03:32:51 -0400 Received: from m43-7.mailgun.net ([69.72.43.7]:64948 "EHLO m43-7.mailgun.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229741AbhFQHcs (ORCPT ); Thu, 17 Jun 2021 03:32:48 -0400 DKIM-Signature: a=rsa-sha256; v=1; c=relaxed/relaxed; d=mg.codeaurora.org; q=dns/txt; s=smtp; t=1623915040; h=Content-Transfer-Encoding: Content-Type: In-Reply-To: MIME-Version: Date: Message-ID: From: References: Cc: To: Subject: Sender; bh=/Ke8K41Ww1WXgC0r6DX1WkuK3ujBCCEjuiXUNiIGjTs=; b=U4ydUD+y0WFxuGLzPpNe9YGUwiUDG5/M7v4OyVjlko2N9IFQyioBLwsxWTwzLg/4rEt9FBlq XGAeFMDoDgiTlUQSADq/Z/PcPtxxzyad6sk3Yt3GUAgty1Qajpk5WokXCxNd+nmgTq4MLcgy rZ6a9MQlOQZLhd2UF/O/ivCh0SA= X-Mailgun-Sending-Ip: 69.72.43.7 X-Mailgun-Sid: WyI0MWYwYSIsICJsaW51eC1rZXJuZWxAdmdlci5rZXJuZWwub3JnIiwgImJlOWU0YSJd Received: from smtp.codeaurora.org (ec2-35-166-182-171.us-west-2.compute.amazonaws.com [35.166.182.171]) by smtp-out-n02.prod.us-east-1.postgun.com with SMTP id 60cafa11e27c0cc77f19d765 (version=TLS1.2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256); Thu, 17 Jun 2021 07:30:25 GMT Sender: charante=codeaurora.org@mg.codeaurora.org Received: by smtp.codeaurora.org (Postfix, from userid 1001) id 95D30C433D3; Thu, 17 Jun 2021 07:30:24 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-caf-mail-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-3.2 required=2.0 tests=ALL_TRUSTED,BAYES_00, NICE_REPLY_A,SPF_FAIL autolearn=no autolearn_force=no version=3.4.0 Received: from [192.168.29.110] (unknown [49.37.156.228]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) (Authenticated sender: charante) by smtp.codeaurora.org (Postfix) with ESMTPSA id BEB16C433F1; Thu, 17 Jun 2021 07:30:15 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 smtp.codeaurora.org BEB16C433F1 Authentication-Results: aws-us-west-2-caf-mail-1.web.codeaurora.org; dmarc=none (p=none dis=none) header.from=codeaurora.org Authentication-Results: aws-us-west-2-caf-mail-1.web.codeaurora.org; spf=fail smtp.mailfrom=charante@codeaurora.org Subject: Re: [PATCH v3 1/2] mm: compaction: support triggering of proactive compaction by user To: Vlastimil Babka , akpm@linux-foundation.org, nigupta@nvidia.com, hannes@cmpxchg.org, corbet@lwn.net, mcgrof@kernel.org, keescook@chromium.org, yzaikin@google.com, aarcange@redhat.com, cl@linux.com, xi.fengfei@h3c.com, mchehab+huawei@kernel.org, andrew.a.klychkov@gmail.com, dave.hansen@linux.intel.com, bhe@redhat.com, iamjoonsoo.kim@lge.com, mateusznosek0@gmail.com, sh_def@163.com, vinmenon@codeaurora.org Cc: linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-fsdevel@vger.kernel.org References: <7db6a29a64b29d56cde46c713204428a4b95f0ab.1622454385.git.charante@codeaurora.org> <88abfdb6-2c13-b5a6-5b46-742d12d1c910@suse.cz> From: Charan Teja Kalla Message-ID: <0ca491e8-6d3a-6537-dfa0-ece5f3bb6a1e@codeaurora.org> Date: Thu, 17 Jun 2021 13:00:13 +0530 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Thunderbird/78.11.0 MIME-Version: 1.0 In-Reply-To: <88abfdb6-2c13-b5a6-5b46-742d12d1c910@suse.cz> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Thanks Vlastimil for your inputs!! On 6/16/2021 5:29 PM, Vlastimil Babka wrote: >> This triggering of proactive compaction is done on a write to >> sysctl.compaction_proactiveness by user. >> >> [1]https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit?id=facdaa917c4d5a376d09d25865f5a863f906234a >> >> Signed-off-by: Charan Teja Reddy >> --- >> changes in V2: > You forgot to also summarize the changes. Please do in next version. Sure. Will take care this in the next version. > >> */ >> unsigned int __read_mostly sysctl_compaction_proactiveness = 20; >> >> +int compaction_proactiveness_sysctl_handler(struct ctl_table *table, int write, >> + void *buffer, size_t *length, loff_t *ppos) >> +{ >> + int rc, nid; >> + >> + rc = proc_dointvec_minmax(table, write, buffer, length, ppos); >> + if (rc) >> + return rc; >> + >> + if (write && sysctl_compaction_proactiveness) { >> + for_each_online_node(nid) { >> + pg_data_t *pgdat = NODE_DATA(nid); >> + >> + if (pgdat->proactive_compact_trigger) >> + continue; >> + >> + pgdat->proactive_compact_trigger = true; > I don't like the new variable. I wish we could do without it. I understand this > is added to ignore proactive_defer. > We could instead expose proactive_defer in pgdat and reset it to 0 before wakeup > (instead being a thread variable in kcompactd). But that would be racy with the > decreases done by kcompactd. > But I like the patch 2/2 and the idea could be extended to proactive_defer > handling. If there's no proactive_defer, timeout is > HPAGE_FRAG_CHECK_INTERVAL_MSEC. If kcompactd decides to defer, timeout would be > HPAGE_FRAG_CHECK_INTERVAL_MSEC << COMPACT_MAX_DEFER_SHIFT. Thus, no more waking > up just to decrease proactive_defer, we can then get rid of the counter. On > writing new proactiveness just wake up and that's it, regardless of which > timeout there was at the moment. I think we can get rid off 'proactive_defer' thread variable with the timeout approach you suggested. But it is still requires to have one additional variable 'proactive_compact_trigger', which main purpose is to decide if the kcompactd wakeup is for proactive compaction or not. Please see below code: if (wait_event_freezable_timeout() && !proactive_compact_trigger) { // do the non-proactive work continue } // do the proactive work ................. Thus I feel that on writing new proactiveness, it is required to do wakeup_kcomppactd() + set a flag that this wakeup is for proactive work. Am I failed to get your point here? > The only change is, if we get woken up to do non-proactive work, by > wakeup_kcompactd(), the proactive_defer value would be now be effectively lost. > I think it's OK as wakeup_kcompactd() means the condition of the zone changed > substantionally anyway and carrying on with previous defer makes not much sense. > What do you think? Agree. > >> + wake_up_interruptible(&pgdat->kcompactd_wait); >> + } >> + } >> + >> + return 0; >> +} >> + >> /* >> * This is the entry point for compacting all nodes via >> * /proc/sys/vm/compact_memory >> @@ -2752,7 +2776,8 @@ void compaction_unregister_node(struct node *node) >> >> static inline bool kcompactd_work_requested(pg_data_t *pgdat) >> { >> - return pgdat->kcompactd_max_order > 0 || kthread_should_stop(); >> + return pgdat->kcompactd_max_order > 0 || kthread_should_stop() || >> + pgdat->proactive_compact_trigger; >> } >> >> static bool kcompactd_node_suitable(pg_data_t *pgdat) >> @@ -2905,7 +2930,8 @@ static int kcompactd(void *p) >> trace_mm_compaction_kcompactd_sleep(pgdat->node_id); >> if (wait_event_freezable_timeout(pgdat->kcompactd_wait, >> kcompactd_work_requested(pgdat), >> - msecs_to_jiffies(HPAGE_FRAG_CHECK_INTERVAL_MSEC))) { >> + msecs_to_jiffies(HPAGE_FRAG_CHECK_INTERVAL_MSEC)) && >> + !pgdat->proactive_compact_trigger) { >> >> psi_memstall_enter(&pflags); >> kcompactd_do_work(pgdat); >> @@ -2917,10 +2943,20 @@ static int kcompactd(void *p) >> if (should_proactive_compact_node(pgdat)) { >> unsigned int prev_score, score; >> >> - if (proactive_defer) { >> + /* >> + * On wakeup of proactive compaction by sysctl >> + * write, ignore the accumulated defer score. >> + * Anyway, if the proactive compaction didn't >> + * make any progress for the new value, it will >> + * be further deferred by 2^COMPACT_MAX_DEFER_SHIFT >> + * times. >> + */ >> + if (proactive_defer && >> + !pgdat->proactive_compact_trigger) { >> proactive_defer--; >> continue; >> } >> + >> prev_score = fragmentation_score_node(pgdat); >> proactive_compact_node(pgdat); >> score = fragmentation_score_node(pgdat); >> @@ -2931,6 +2967,8 @@ static int kcompactd(void *p) >> proactive_defer = score < prev_score ? >> 0 : 1 << COMPACT_MAX_DEFER_SHIFT; >> } >> + if (pgdat->proactive_compact_trigger) >> + pgdat->proactive_compact_trigger = false; >> } >> >> return 0; -- The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum, a Linux Foundation Collaborative Project