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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 84128C433F5 for ; Sat, 22 Jan 2022 09:50:47 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231843AbiAVJur (ORCPT ); Sat, 22 Jan 2022 04:50:47 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:48390 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229773AbiAVJuq (ORCPT ); Sat, 22 Jan 2022 04:50:46 -0500 Received: from mail-qt1-x82b.google.com (mail-qt1-x82b.google.com [IPv6:2607:f8b0:4864:20::82b]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 26F0CC06173B for ; Sat, 22 Jan 2022 01:50:45 -0800 (PST) Received: by mail-qt1-x82b.google.com with SMTP id h15so13031989qtx.0 for ; Sat, 22 Jan 2022 01:50:45 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=mime-version:references:in-reply-to:from:date:message-id:subject:to; bh=/DvivhbrHIY4f17iliBHPV/kS4qRh7JJhxcfM6F15FI=; b=KT3hk/STET5VuhcsVl0dSnqPd5cHz7tzpsyNVWb62Ck6N85363yhKnMV4tVI2S7X2X rCIpPqYYwIjwVYsFJSaolhdHr3yxtgiFLBf3qwoQJmUyiK+K8ED9BPJnSEa1+os1xJr0 a2kOG2fsJxDOntLwpOpzqsCGEYRMDX41zY6RpgMXDae4K3zNAFEBW5f0iQvHvvBMWTpJ kasANM/E6rzDHUHck3pkfk+qtO9fkx5kBXhB1vk2XZdFXSLQrldNOC9vxBnPZzOqF6ms ZeBh6tNi4eQ63lMUAB99ylbBFhtpNgRSHu5nTaj6mjCYFfHXyvjuuvvWsFv5PlN2qhVE 8q8A== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to; bh=/DvivhbrHIY4f17iliBHPV/kS4qRh7JJhxcfM6F15FI=; b=NMu4ZfUe0bHKDKSCUDN0FfKsZfxENOH40lobEqALYcBkfiP0UL8A8ERWVpGuy2OYoz 9Ptfqns54kvk/Iedb96Gdn/2g1gRNKNzVbHHmAuXwe/pf6UaByTgiHYhfAb3dd8xr6Bj kZ4mOwTJgBL01G4s8dWOnxUPII1yG2CaA04K0tNcgCH3VLFnzpxglyiwO2lmdu7d7yz3 bAC4e4amirZHkhFI+6J5FTYmWjQeF8Ha/NN5ZENr6Paoiq37vzssVByFL2ZsDfD8rt9x ZhQCvh8nYnTyp6yhM6yUcx8uChjRDfAa86cIx4r3Ojo2rDyKjzhqv2H9Ovxznq1XRfu/ PxkA== X-Gm-Message-State: AOAM532k/R66ST9zOMqptumRQN0W0ChKEHcJrAbKf7GC+kIuVQmxu+Ft 1zZmL4fkMTKcza127GXV199iRW2/xP5apDeHwTs= X-Google-Smtp-Source: ABdhPJyQYqn281mdojFMqETNlLuw4H/1mQrK+zUsXLy7tZTw3i9h2sBlFf+uz6cKqcQ1VNG8G7LO7d29gH3Op8Gm8fc= X-Received: by 2002:ac8:5bd5:: with SMTP id b21mr6195415qtb.68.1642845044338; Sat, 22 Jan 2022 01:50:44 -0800 (PST) MIME-Version: 1.0 References: <1642649516-15076-1-git-send-email-huangzhaoyang@gmail.com> In-Reply-To: <1642649516-15076-1-git-send-email-huangzhaoyang@gmail.com> From: Zhaoyang Huang Date: Sat, 22 Jan 2022 17:50:06 +0800 Message-ID: Subject: Re: [Resend PATCH v3] psi: fix possible trigger missing in the window To: Johannes Weiner , Suren Baghdasaryan , Peter Zijlstra , Zhaoyang Huang , Ingo Molnar , "open list:MEMORY MANAGEMENT" , LKML Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org sorry for broadcasting here. Is anyone aware of Johannes and Peter's status? The following patch has been waiting for their comments for a long time. Are they available recently? thanks. On Thu, Jan 20, 2022 at 11:32 AM Huangzhaoyang wrote: > > 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); > > -- > 1.9.1 >