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 X-Spam-Level: X-Spam-Status: No, score=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by aws-us-west-2-korg-lkml-1.web.codeaurora.org (Postfix) with ESMTP id 69FE4C5CFC1 for ; Fri, 15 Jun 2018 16:07:35 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 2AD57208B2 for ; Fri, 15 Jun 2018 16:07:35 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 2AD57208B2 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=icdsoft.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S966013AbeFOQHc (ORCPT ); Fri, 15 Jun 2018 12:07:32 -0400 Received: from us.icdsoft.com ([192.252.146.184]:43668 "EHLO us.icdsoft.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S965947AbeFOQHa (ORCPT ); Fri, 15 Jun 2018 12:07:30 -0400 Received: (qmail 5552 invoked by uid 1001); 15 Jun 2018 16:07:30 -0000 Received: from unknown (HELO ?94.155.37.249?) (famzah@94.155.37.249) by 192.252.159.165 with ESMTPA; 15 Jun 2018 16:07:30 -0000 Subject: Re: Cgroups "pids" controller does not update "pids.current" count immediately To: Tejun Heo Cc: cgroups@vger.kernel.org, linux-kernel@vger.kernel.org References: <77af3805-e912-2664-f347-e30c0919d0c4@icdsoft.com> <20180614150650.GU1351649@devbig577.frc2.facebook.com> <7860105c-553a-534b-57fc-222d931cb972@icdsoft.com> <20180615154140.GV1351649@devbig577.frc2.facebook.com> From: Ivan Zahariev Message-ID: <1d635d1d-6152-ecfc-d235-147ff1fe7c95@icdsoft.com> Date: Fri, 15 Jun 2018 19:07:27 +0300 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:52.0) Gecko/20100101 Thunderbird/52.8.0 MIME-Version: 1.0 In-Reply-To: <20180615154140.GV1351649@devbig577.frc2.facebook.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit Content-Language: en-bg Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi, Thank you for the quick and insightful reply. I have one suggestion below: On 15.6.2018 г. 18:41 ч., Tejun Heo wrote: > On Fri, Jun 15, 2018 at 05:26:04PM +0300, Ivan Zahariev wrote: >> The standard RLIMIT_NPROC does not suffer from such accounting >> discrepancies at any time. > They seem equivalent but serve a bit different purposes. RLIMIT_NPROC > is primarily about limiting what the user can do and doesn't guarantee > that that actually matches resource (pid here) consumption. > >> Is it really technically not possible to make "pids.current" do >> accounting properly like RLIMIT_NPROC does? We were hoping to >> replace RLIMIT_NPROC with the "pids" controller. > It is of course possible but at a cost. The cost (getting rid of lazy > release optimizations) is just not justifiable for most cases. I understand all concerns and design decisions. However, having RLIMIT_NPROC support combined with "cgroups" hierarchy would be very handy. Does it make sense that you introduce "nproc.current" and "nproc.max" metrics which work in the same atomic, real-time way like RLIMIT_NPROC? Or make this in a new "nproc" controller? -- Ivan --