From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 295A81509BC for ; Thu, 11 Jul 2024 21:00:54 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.129.124 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1720731656; cv=none; b=XLspHL6BVZBZjR5s+JifbnDXWWAbKpJ4Q/bk1Qhj9b6vMFwKOFB4712FCjnJWgmWnnddVl7j7JWwGdd9YHtUzFyscJ0fMPBMoLBLMJWCcUf+M7soGSTsEDwsvY7K0EwaU+3FPKQqqPnkC72/xj+zFHkcanhYybtDVEnRepLLYQw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1720731656; c=relaxed/simple; bh=xJC3q5B+KIdmgj2GicJ24IEhPqmpJfMZ6JvdQhrHz2A=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=ZWF3yRbbvieV5LZkYPYgo1ohxAsymO0E2+vYWtUHBQPA/hPG4MGupwPdghvJhmhzKeq6zRvZw4PHH5LyFxB1agWC/ujGdP0UQCZvk3/MgdefiPdU3OsxyT/7mMhJJ9r/ot51mzr5KrEc+6+m3yEbnct6FEeFNz0ibDcdxxHyT3w= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=redhat.com; spf=pass smtp.mailfrom=redhat.com; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b=WVfJpWB2; arc=none smtp.client-ip=170.10.129.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=redhat.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=redhat.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="WVfJpWB2" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1720731652; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=uXzacATyJ7+hzQa34R1FMVM/asZbvciRl5Ud+bdS400=; b=WVfJpWB2uK79S6na8f+MX4XctgKz7hF8DzfiW1X0l9rXtDGz9IuIl5BFjVjmg9sz1rclSQ 1ao6UBBJenxt535+ivWnGwA6Zxd6m3Js2xFzOyrhaMO4wQoZAw7lXE4hjT4E5jPoeDgA38 KRPexgJiPaYpS07GRt+nRG6kd4/5Dy0= Received: from mx-prod-mc-02.mail-002.prod.us-west-2.aws.redhat.com (ec2-54-186-198-63.us-west-2.compute.amazonaws.com [54.186.198.63]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-145-YAmcdNS6MqSuZzLs16-iDw-1; Thu, 11 Jul 2024 17:00:48 -0400 X-MC-Unique: YAmcdNS6MqSuZzLs16-iDw-1 Received: from mx-prod-int-05.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-05.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.17]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-02.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 820121955F43; Thu, 11 Jul 2024 21:00:44 +0000 (UTC) Received: from [10.22.64.119] (unknown [10.22.64.119]) by mx-prod-int-05.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTP id A0FED1955F40; Thu, 11 Jul 2024 21:00:42 +0000 (UTC) Message-ID: Date: Thu, 11 Jul 2024 17:00:41 -0400 Precedence: bulk X-Mailing-List: cgroups@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v3 1/2] cgroup: Show # of subsystem CSSes in cgroup.stat To: Johannes Weiner Cc: Tejun Heo , Zefan Li , Jonathan Corbet , cgroups@vger.kernel.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, Kamalesh Babulal , Roman Gushchin References: <20240710182353.2312025-1-longman@redhat.com> <20240711134927.GB456706@cmpxchg.org> <4e1078d6-6970-4eea-8f73-56a3815794b5@redhat.com> <76e70789-986a-44c2-bfdc-d636f425e5ae@redhat.com> <20240711195946.GA1094169@cmpxchg.org> Content-Language: en-US From: Waiman Long In-Reply-To: <20240711195946.GA1094169@cmpxchg.org> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 3.0 on 10.30.177.17 On 7/11/24 15:59, Johannes Weiner wrote: > On Thu, Jul 11, 2024 at 03:13:12PM -0400, Waiman Long wrote: >> On 7/11/24 14:59, Tejun Heo wrote: >>> On Thu, Jul 11, 2024 at 02:51:38PM -0400, Waiman Long wrote: >>>> On 7/11/24 14:44, Tejun Heo wrote: >>>>> Hello, >>>>> >>>>> On Thu, Jul 11, 2024 at 01:39:38PM -0400, Waiman Long wrote: >>>>>> On 7/11/24 13:18, Tejun Heo wrote: >>>>> ... >>>>>> Currently, I use the for_each_css() macro for iteration. If you mean >>>>>> displaying all the possible cgroup subsystems even if they are not enabled >>>>>> for the current cgroup, I will have to manually do the iteration. >>>>> Just wrapping it with for_each_subsys() should do, no? for_each_css() won't >>>>> iterate anything if css doesn't exist for the cgroup. >>>> OK, I wasn't sure if you were asking to list all the possible cgroup v2 >>>> cgroup subsystems even if they weren't enabled in the current cgroup. >>>> Apparently, that is the case. I prefer it that way too. >>> Yeah, I think listing all is better. If the list corresponded directly to >>> cgroup.controllers, it may make sense to only show enabled ones but we can >>> have dying ones and implicitly enabled memory and so on, so I think it'd be >>> cleaner to just list them all. >> That will means cgroup subsystems that are seldomly used like rdma, misc >> or even hugetlb will always be shown in all the cgroup.stat output. I >> actually prefer just showing those that are enabled. As for dying memory >> cgroups, they will only be shown in its online ancestors. We currently >> don't know how many level down are each of the dying ones. > It seems odd to me to not show dead ones after a cgroup has disabled > the controller again. They still consume memory, after all, and so > continue to be property of that cgroup afterwards. > > Instead of doing for_each_css(), would it make more sense to have > > struct cgroup { > ... > int nr_dying_subsys[CGROUP_SUBSYS_COUNT]; What exactly does new this array for? Is this for copying out css->nr_dying_descendants before disabling a controller? The number may be out of date when it is used. I would think we should store the actual css and clearing it again once the css is ready to be freed. Anyway, I would suggest doing it as a separate add-on patch if we decide to do it instead of adding it to the current patch. Cheers, Longman