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 X-Spam-Level: X-Spam-Status: No, score=-16.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 57101C12002 for ; Wed, 21 Jul 2021 12:13:47 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 2656C6120F for ; Wed, 21 Jul 2021 12:13:47 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236144AbhGULdJ (ORCPT ); Wed, 21 Jul 2021 07:33:09 -0400 Received: from so254-9.mailgun.net ([198.61.254.9]:36155 "EHLO so254-9.mailgun.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232079AbhGULdH (ORCPT ); Wed, 21 Jul 2021 07:33:07 -0400 DKIM-Signature: a=rsa-sha256; v=1; c=relaxed/relaxed; d=mg.codeaurora.org; q=dns/txt; s=smtp; t=1626869624; h=Message-Id: Date: Subject: Cc: To: From: Sender; bh=9ORgIVwVR1hRA3DPeFL9fUMvBLk6pAhPJpSd8Q2TU54=; b=AJiAptwRrO3et1YquBNRj/RFjGX/Ie9bb8oqhyGae2xpkfboqHG+GE7sP8/RgqhLsuhkTEOZ MGhBj2fE5/XYHV30m4way19NTOwKsEhAeU3Cemcicup47TX3RdKu+kUoE3GVmNx2vxDYiVjL DF/HE6ruotaMfAdcIZ3UuBKATHc= X-Mailgun-Sending-Ip: 198.61.254.9 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-n03.prod.us-east-1.postgun.com with SMTP id 60f80f6cb653fbdaddc41e9c (version=TLS1.2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256); Wed, 21 Jul 2021 12:13:32 GMT Sender: charante=codeaurora.org@mg.codeaurora.org Received: by smtp.codeaurora.org (Postfix, from userid 1001) id 6CBD6C43460; Wed, 21 Jul 2021 12:13:31 +0000 (UTC) Received: from hu-charante-hyd.qualcomm.com (unknown [202.46.22.19]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-SHA256 (128/128 bits)) (No client certificate requested) (Authenticated sender: charante) by smtp.codeaurora.org (Postfix) with ESMTPSA id ED701C433D3; Wed, 21 Jul 2021 12:13:26 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 smtp.codeaurora.org ED701C433D3 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 From: Charan Teja Reddy To: akpm@linux-foundation.org, vbabka@suse.cz, rientjes@google.com, nigupta@nvidia.com, khalid.aziz@oracle.com Cc: vinmenon@codeaurora.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, Charan Teja Reddy Subject: [PATCH resend] mm: compaction: optimize proactive compaction deferrals Date: Wed, 21 Jul 2021 17:43:19 +0530 Message-Id: <1626869599-25412-1-git-send-email-charante@codeaurora.org> X-Mailer: git-send-email 2.7.4 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Vlastimil Babka figured out that when fragmentation score didn't go down across the proactive compaction i.e. when no progress is made, next wake up for proactive compaction is deferred for 1 << COMPACT_MAX_DEFER_SHIFT, i.e. 64 times, with each wakeup interval of HPAGE_FRAG_CHECK_INTERVAL_MSEC(=500). In each of this wakeup, it just decrement 'proactive_defer' counter and goes sleep i.e. it is getting woken to just decrement a counter. The same deferral time can also achieved by simply doing the HPAGE_FRAG_CHECK_INTERVAL_MSEC << COMPACT_MAX_DEFER_SHIFT thus unnecessary wakeup of kcompact thread is avoided thus also removes the need of 'proactive_defer' thread counter. Link: https://lore.kernel.org/linux-fsdevel/88abfdb6-2c13-b5a6-5b46-742d12d1c910@suse.cz/ Signed-off-by: Charan Teja Reddy --- Changes in V1: o Removed the 'proactive_defer' thread counter by optimizing proactive o This is a resend as earlier it was clubbed with other changes posted at https://lore.kernel.org/patchwork/patch/1448789/ mm/compaction.c | 29 +++++++++++++++++++---------- 1 file changed, 19 insertions(+), 10 deletions(-) diff --git a/mm/compaction.c b/mm/compaction.c index 621508e..db00dbf 100644 --- a/mm/compaction.c +++ b/mm/compaction.c @@ -2885,7 +2885,8 @@ static int kcompactd(void *p) { pg_data_t *pgdat = (pg_data_t *)p; struct task_struct *tsk = current; - unsigned int proactive_defer = 0; + long default_timeout = msecs_to_jiffies(HPAGE_FRAG_CHECK_INTERVAL_MSEC); + long timeout = default_timeout; const struct cpumask *cpumask = cpumask_of_node(pgdat->node_id); @@ -2902,23 +2903,30 @@ 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))) { + kcompactd_work_requested(pgdat), timeout)) { psi_memstall_enter(&pflags); kcompactd_do_work(pgdat); psi_memstall_leave(&pflags); + /* + * Reset the timeout value. The defer timeout by + * proactive compaction can effectively lost + * here but that is fine as the condition of the + * zone changed substantionally and carrying on + * with the previous defer is not useful. + */ + timeout = default_timeout; continue; } - /* kcompactd wait timeout */ + /* + * Start the proactive work with default timeout. Based + * on the fragmentation score, this timeout is updated. + */ + timeout = default_timeout; if (should_proactive_compact_node(pgdat)) { unsigned int prev_score, score; - if (proactive_defer) { - proactive_defer--; - continue; - } prev_score = fragmentation_score_node(pgdat); proactive_compact_node(pgdat); score = fragmentation_score_node(pgdat); @@ -2926,8 +2934,9 @@ static int kcompactd(void *p) * Defer proactive compaction if the fragmentation * score did not go down i.e. no progress made. */ - proactive_defer = score < prev_score ? - 0 : 1 << COMPACT_MAX_DEFER_SHIFT; + if (unlikely(score >= prev_score)) + timeout = + default_timeout << COMPACT_MAX_DEFER_SHIFT; } } -- QUALCOMM INDIA, on behalf of Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum, hosted by The Linux Foundation