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 D5AEFC433EF for ; Tue, 17 May 2022 09:38:53 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234369AbiEQJid (ORCPT ); Tue, 17 May 2022 05:38:33 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:57762 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S244916AbiEQJiY (ORCPT ); Tue, 17 May 2022 05:38:24 -0400 Received: from szxga08-in.huawei.com (szxga08-in.huawei.com [45.249.212.255]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id F390844A02; Tue, 17 May 2022 02:38:19 -0700 (PDT) Received: from dggpemm500023.china.huawei.com (unknown [172.30.72.56]) by szxga08-in.huawei.com (SkyGuard) with ESMTP id 4L2WGy2RZjz1JCD8; Tue, 17 May 2022 17:36:58 +0800 (CST) Received: from dggpemm500002.china.huawei.com (7.185.36.229) by dggpemm500023.china.huawei.com (7.185.36.83) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.24; Tue, 17 May 2022 17:38:18 +0800 Received: from [10.174.178.178] (10.174.178.178) by dggpemm500002.china.huawei.com (7.185.36.229) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.24; Tue, 17 May 2022 17:38:17 +0800 Message-ID: <3bbb684d-e5b2-ee22-bf74-e4ffe6ab89e1@huawei.com> Date: Tue, 17 May 2022 17:38:17 +0800 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:91.0) Gecko/20100101 Thunderbird/91.0.3 Subject: Re: [PATCH 1/2] psi: add support for multi level pressure stall trigger To: Suren Baghdasaryan , Alex Shi CC: LKML , Johannes Weiner , Alex Shi , Jonathan Corbet , "open list:DOCUMENTATION" References: <20220516033524.3130816-1-chenwandun@huawei.com> <30b37eeb-e77b-882e-fc24-3367321a8ca3@gmail.com> From: Chen Wandun In-Reply-To: Content-Type: text/plain; charset="UTF-8"; format=flowed Content-Transfer-Encoding: 8bit X-Originating-IP: [10.174.178.178] X-ClientProxiedBy: dggems706-chm.china.huawei.com (10.3.19.183) To dggpemm500002.china.huawei.com (7.185.36.229) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 在 2022/5/16 16:21, Suren Baghdasaryan 写道: > On Sun, May 15, 2022 at 11:20 PM Alex Shi wrote: >> >> >> On 5/16/22 11:35, Chen Wandun wrote: >>> Nowadays, psi events are triggered when stall time exceed >>> stall threshold, but no any different between these events. >>> >>> Actually, events can be divide into multi level, each level >>> represent a different stall pressure, that is help to identify >>> pressure information more accurately. > IIUC by defining min and max, you want the trigger to activate when > the stall is between min and max thresholds. But I don't see why you > would need that. If you want to have several levels, you can create > multiple triggers and monitor them separately. For your example, that > would be: > > echo "some 150000 1000000" > /proc/pressure/memory > echo "some 350000 1000000" > /proc/pressure/memory > > Your first trigger will fire whenever the stall exceeds 150ms within > each 1sec and the second one will trigger when it exceeds 350ms. It is > true that if the stall jumps sharply above 350ms, you would get both > triggers firing. I'm guessing that's why you want this functionality > so that 150ms trigger does not fire when 350ms one is firing but why Yes, if stall time above 350ms, I hope only one trigger fire. > is that a problem? Can't userspace pick the highest level one and > ignore all the lower ones when this happens? Or are you addressing > some other requirement? Userspace can pick the higest level, but more triggers fire, actually one trigger fire is enough in this case, and userspace  become more complex. new trigger is compatible with old. echo "some 150000 1000000 1000000 " > /proc/pressure/memory can achieve the same goal with echo "some 150000 1000000 " > /proc/pressure/memory > >>> echo "some 150000 350000 1000000" > /proc/pressure/memory would >> This breaks the old ABI. And why you need this new function? > Both great points. > >> Thanks >> >>> add [150ms, 350ms) threshold for partial memory stall measured >>> within 1sec time window. >>> >>> Signed-off-by: Chen Wandun >>> --- >>> include/linux/psi_types.h | 3 ++- >>> kernel/sched/psi.c | 19 +++++++++++++------ >>> 2 files changed, 15 insertions(+), 7 deletions(-) >>> >>> diff --git a/include/linux/psi_types.h b/include/linux/psi_types.h >>> index c7fe7c089718..2b1393c8bf90 100644 >>> --- a/include/linux/psi_types.h >>> +++ b/include/linux/psi_types.h >>> @@ -119,7 +119,8 @@ struct psi_trigger { >>> enum psi_states state; >>> >>> /* User-spacified threshold in ns */ >>> - u64 threshold; >>> + u64 min_threshold; >>> + u64 max_threshold; >>> >>> /* List node inside triggers list */ >>> struct list_head node; >>> diff --git a/kernel/sched/psi.c b/kernel/sched/psi.c >>> index 6f9533c95b0a..17dd233b533a 100644 >>> --- a/kernel/sched/psi.c >>> +++ b/kernel/sched/psi.c >>> @@ -541,7 +541,7 @@ static u64 update_triggers(struct psi_group *group, u64 now) >>> >>> /* Calculate growth since last update */ >>> growth = window_update(&t->win, now, total[t->state]); >>> - if (growth < t->threshold) >>> + if (growth < t->min_threshold || growth >= t->max_threshold) >>> continue; >>> >>> t->pending_event = true; >>> @@ -1087,15 +1087,18 @@ struct psi_trigger *psi_trigger_create(struct psi_group *group, >>> { >>> struct psi_trigger *t; >>> enum psi_states state; >>> - u32 threshold_us; >>> + u32 min_threshold_us; >>> + u32 max_threshold_us; >>> u32 window_us; >>> >>> if (static_branch_likely(&psi_disabled)) >>> return ERR_PTR(-EOPNOTSUPP); >>> >>> - if (sscanf(buf, "some %u %u", &threshold_us, &window_us) == 2) >>> + if (sscanf(buf, "some %u %u %u", &min_threshold_us, >>> + &max_threshold_us, &window_us) == 3) >>> state = PSI_IO_SOME + res * 2; >>> - else if (sscanf(buf, "full %u %u", &threshold_us, &window_us) == 2) >>> + else if (sscanf(buf, "full %u %u %u", &min_threshold_us, >>> + &max_threshold_us, &window_us) == 3) >>> state = PSI_IO_FULL + res * 2; >>> else >>> return ERR_PTR(-EINVAL); >>> @@ -1107,8 +1110,11 @@ struct psi_trigger *psi_trigger_create(struct psi_group *group, >>> window_us > WINDOW_MAX_US) >>> return ERR_PTR(-EINVAL); >>> >>> + if (min_threshold_us >= max_threshold_us) >>> + return ERR_PTR(-EINVAL); >>> + >>> /* Check threshold */ >>> - if (threshold_us == 0 || threshold_us > window_us) >>> + if (max_threshold_us > window_us) >>> return ERR_PTR(-EINVAL); >>> >>> t = kmalloc(sizeof(*t), GFP_KERNEL); >>> @@ -1117,7 +1123,8 @@ struct psi_trigger *psi_trigger_create(struct psi_group *group, >>> >>> t->group = group; >>> t->state = state; >>> - t->threshold = threshold_us * NSEC_PER_USEC; >>> + t->min_threshold = min_threshold_us * NSEC_PER_USEC; >>> + t->max_threshold = max_threshold_us * NSEC_PER_USEC; >>> t->win.size = window_us * NSEC_PER_USEC; >>> window_reset(&t->win, 0, 0, 0); >>> > .