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 kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 51751C433EF for ; Fri, 1 Apr 2022 16:59:32 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id D62948D0002; Fri, 1 Apr 2022 12:59:21 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id D10388D0001; Fri, 1 Apr 2022 12:59:21 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id BD7AA8D0002; Fri, 1 Apr 2022 12:59:21 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (relay.hostedemail.com [64.99.140.26]) by kanga.kvack.org (Postfix) with ESMTP id A97418D0001 for ; Fri, 1 Apr 2022 12:59:21 -0400 (EDT) Received: from smtpin02.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay12.hostedemail.com (Postfix) with ESMTP id 809F7121DA2 for ; Fri, 1 Apr 2022 16:59:11 +0000 (UTC) X-FDA: 79308920502.02.DFB0B5D Received: from out0.migadu.com (out0.migadu.com [94.23.1.103]) by imf29.hostedemail.com (Postfix) with ESMTP id AD069120008 for ; Fri, 1 Apr 2022 16:59:10 +0000 (UTC) Date: Fri, 1 Apr 2022 09:58:59 -0700 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1648832348; 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: in-reply-to:in-reply-to:references:references; bh=opfMZhT1sWWFuxdmOUhDIsbcAFNmM7W5eVe4Jw4U7ZY=; b=GGASatQNi5+qmdKAN6sT/OaTjH+8x2+DckJQyi+9uL68dpIUK0DZxNUnLw/yu8t3k5scnA REFoIo1PPbilRLGJ/+iT7OlAQX+BGS5NsW0eaE67YBrb0zG3/dZOa3OiZ/up5QEd9hTrEn xQ54UriLGceRv5Ztvya2fXB8qCs3fxg= X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. From: Roman Gushchin To: Michal Hocko Cc: Yosry Ahmed , Johannes Weiner , Shakeel Butt , Andrew Morton , David Rientjes , Tejun Heo , Zefan Li , cgroups@vger.kernel.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, Jonathan Corbet , Yu Zhao , Dave Hansen , Wei Xu , Greg Thelen Subject: Re: [PATCH resend] memcg: introduce per-memcg reclaim interface Message-ID: References: <20220331084151.2600229-1-yosryahmed@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Migadu-Flow: FLOW_OUT X-Migadu-Auth-User: linux.dev X-Stat-Signature: mt7764n58dnqpdo6domxzdrfunq4gc9f X-Rspamd-Server: rspam07 X-Rspamd-Queue-Id: AD069120008 Authentication-Results: imf29.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b=GGASatQN; dmarc=pass (policy=none) header.from=linux.dev; spf=pass (imf29.hostedemail.com: domain of roman.gushchin@linux.dev designates 94.23.1.103 as permitted sender) smtp.mailfrom=roman.gushchin@linux.dev X-Rspam-User: X-HE-Tag: 1648832350-733984 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: On Fri, Apr 01, 2022 at 03:49:19PM +0200, Michal Hocko wrote: > On Thu 31-03-22 10:25:23, Roman Gushchin wrote: > > On Thu, Mar 31, 2022 at 08:41:51AM +0000, Yosry Ahmed wrote: > [...] > > > - A similar per-node interface can also be added to support proactive > > > reclaim and reclaim-based demotion in systems without memcg. > > > > Maybe an option to specify a timeout? That might simplify the userspace part. > > What do you mean by timeout here? Isn't > timeout $N echo $RECLAIM > .... > > enough? It's nice and simple when it's a bash script, but when it's a complex application trying to do the same, it quickly becomes less simple and likely will require a dedicated thread to avoid blocking the main app for too long and a mechanism to unblock it by timer/when the need arises. In my experience using correctly such semi-blocking interfaces (semi- because it's not clearly defined how much time the syscall can take and whether it makes sense to wait longer) is tricky.