From patchwork Wed Jan 12 01:47:54 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Zhaoyang Huang X-Patchwork-Id: 12710876 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 CC8DAC433FE for ; Wed, 12 Jan 2022 01:48:17 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 09ABF6B0108; Tue, 11 Jan 2022 20:48:17 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 04B936B0109; Tue, 11 Jan 2022 20:48:17 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id E54446B010A; Tue, 11 Jan 2022 20:48:16 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0064.hostedemail.com [216.40.44.64]) by kanga.kvack.org (Postfix) with ESMTP id D41D86B0108 for ; Tue, 11 Jan 2022 20:48:16 -0500 (EST) Received: from smtpin11.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay04.hostedemail.com (Postfix) with ESMTP id 6AB1D951A6 for ; Wed, 12 Jan 2022 01:48:16 +0000 (UTC) X-FDA: 79019949792.11.A859402 Received: from mail-pl1-f173.google.com (mail-pl1-f173.google.com [209.85.214.173]) by imf04.hostedemail.com (Postfix) with ESMTP id 1E8B34000D for ; Wed, 12 Jan 2022 01:48:15 +0000 (UTC) Received: by mail-pl1-f173.google.com with SMTP id u15so1809464ple.2 for ; Tue, 11 Jan 2022 17:48:15 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=from:to:subject:date:message-id; bh=6VcCCa/uNyu5klYi1x3xHgmWoLaBIpIlwVyG80i3crM=; b=b6tcahg+T5y6YlhZy6IKeQPGYgsVya1Q7MB3pxrTeKA6FtL+k6+I0MUZDBoelpg8p/ 4N0QqftZDjoNOPjaWcBIpvc/3cx5eQ6pugbR8kfzd458vkjJMW2uAZpp3kTFY7QBc7OQ MFBuo6oM1wCYiMmC0wRyX8WH6rEGVgUcP24q54DlDX99YkenTYutj3Oz3Py8kuo4yTsl rqvFvsBZJDAcFxnXQfrd9j3pX1TweqcJmXcNT0AyAvO27ZO0WMcRKYmQL02YUusWM+Hl Fh5O6aWWJsuPHm1h/JnE8OgnIpp8EDTL3OA6y7w0U30is7zeUAERa934Im0xY0CTVaD6 taoA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:from:to:subject:date:message-id; bh=6VcCCa/uNyu5klYi1x3xHgmWoLaBIpIlwVyG80i3crM=; b=TItNZ2adrbgATrYPGR/spHKI2kdqriA7JnXERaChrnkTvD3u3SB3J87mZDDxO22iWE JXt7QWxSg5Hg7U2eN3XhS7okLhle6wL8qPCSWUfMH6hDXcX94rvL1UkQnV7gfl2H6IOl F+ZeA01gCvgx6bEWIBGGOBfANQiaus4sIIwbrbt5tNNuKdWD1hgHiapVlRzQOhzLIEbs 3o4FYiBEfuYs1jpxpBc6M/5z870KHjMkGgyyeM+1BK/KkylWe8vIM/Od0JKLZ9OjaAqT hCxiJjAwEPrVna6uiaADKCqfEAPFH2lr0dsywbDRL230BVyeMrtx8Eh0CdYxRKV5VJ6f /H8w== X-Gm-Message-State: AOAM530acBSrczIl1ZJRYxlUCvV6N7oNEqwS4Iq6JRS0XnEC+rcpX97H zKK3uMRodHxfODFvBzUhCnw= X-Google-Smtp-Source: ABdhPJwkl7mjvLoPUcMoCFkGXqaBTVoTFEXx8USTKJtId9VY0sd+VqYdnFtCLmH/j83sT7OXiXOqpQ== X-Received: by 2002:a17:90b:4a51:: with SMTP id lb17mr6157575pjb.118.1641952095044; Tue, 11 Jan 2022 17:48:15 -0800 (PST) Received: from bj03382pcu.spreadtrum.com ([117.18.48.102]) by smtp.gmail.com with ESMTPSA id w6sm541801pga.25.2022.01.11.17.48.12 (version=TLS1_2 cipher=ECDHE-ECDSA-AES128-GCM-SHA256 bits=128/128); Tue, 11 Jan 2022 17:48:14 -0800 (PST) From: Huangzhaoyang To: Johannes Weiner , Suren Baghdasaryan , Peter Zijlstra , Zhaoyang Huang , Ingo Molnar , linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: [Resend PATCH v3] psi: fix possible trigger missing in the window Date: Wed, 12 Jan 2022 09:47:54 +0800 Message-Id: <1641952074-5041-1-git-send-email-huangzhaoyang@gmail.com> X-Mailer: git-send-email 1.7.9.5 X-Rspamd-Queue-Id: 1E8B34000D X-Stat-Signature: xc1iyhrrfun3bu6or7ay4fq8qn7o9yah Authentication-Results: imf04.hostedemail.com; dkim=pass header.d=gmail.com header.s=20210112 header.b=b6tcahg+; dmarc=pass (policy=none) header.from=gmail.com; spf=pass (imf04.hostedemail.com: domain of huangzhaoyang@gmail.com designates 209.85.214.173 as permitted sender) smtp.mailfrom=huangzhaoyang@gmail.com X-Rspamd-Server: rspam02 X-HE-Tag: 1641952095-2028 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: Zhaoyang Huang When a new threshold breaching stall happens after a psi event was generated and within the window duration, the new event is not generated because the events are rate-limited to one per window. If after that no new stall is recorded then the event will not be generated even after rate-limiting duration has passed. This is happening because with no new stall, window_update will not be called even though threshold was previously breached. To fix this, record threshold breaching occurrence and generate the event once window duration is passed. Suggested-by: Suren Baghdasaryan Signed-off-by: Zhaoyang Huang --- v2: modify the logic according to Suren's suggestion v3: update commit message --- --- include/linux/psi_types.h | 2 ++ kernel/sched/psi.c | 38 +++++++++++++++++++++++--------------- 2 files changed, 25 insertions(+), 15 deletions(-) diff --git a/include/linux/psi_types.h b/include/linux/psi_types.h index 0a23300..87b694a 100644 --- a/include/linux/psi_types.h +++ b/include/linux/psi_types.h @@ -132,6 +132,8 @@ struct psi_trigger { /* Refcounting to prevent premature destruction */ struct kref refcount; + + bool threshold_breach; }; struct psi_group { diff --git a/kernel/sched/psi.c b/kernel/sched/psi.c index 1652f2b..5c67ab9 100644 --- a/kernel/sched/psi.c +++ b/kernel/sched/psi.c @@ -524,24 +524,29 @@ static u64 update_triggers(struct psi_group *group, u64 now) */ list_for_each_entry(t, &group->triggers, node) { u64 growth; + bool trigger_stalled = + group->polling_total[t->state] != total[t->state]; - /* Check for stall activity */ - if (group->polling_total[t->state] == total[t->state]) - continue; - - /* - * Multiple triggers might be looking at the same state, - * remember to update group->polling_total[] once we've - * been through all of them. Also remember to extend the - * polling time if we see new stall activity. - */ - new_stall = true; - - /* Calculate growth since last update */ - growth = window_update(&t->win, now, total[t->state]); - if (growth < t->threshold) + /* Check for stall activity or a previous threshold breach */ + if (!trigger_stalled && !t->threshold_breach) continue; + if (trigger_stalled) { + /* + * Multiple triggers might be looking at the same state, + * remember to update group->polling_total[] once we've + * been through all of them. Also remember to extend the + * polling time if we see new stall activity. + */ + new_stall = true; + + /* Calculate growth since last update */ + growth = window_update(&t->win, now, total[t->state]); + if (growth < t->threshold) + continue; + + t->threshold_breach = true; + } /* Limit event signaling to once per window */ if (now < t->last_event_time + t->win.size) continue; @@ -550,6 +555,8 @@ static u64 update_triggers(struct psi_group *group, u64 now) if (cmpxchg(&t->event, 0, 1) == 0) wake_up_interruptible(&t->event_wait); t->last_event_time = now; + /* Reset threshold breach flag once event got generated */ + t->threshold_breach = false; } if (new_stall) @@ -1152,6 +1159,7 @@ struct psi_trigger *psi_trigger_create(struct psi_group *group, t->last_event_time = 0; init_waitqueue_head(&t->event_wait); kref_init(&t->refcount); + t->threshold_breach = false; mutex_lock(&group->trigger_lock);