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 8D963C433EF for ; Fri, 15 Jun 2018 14:32:52 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 4979C20896 for ; Fri, 15 Jun 2018 14:32:52 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 4979C20896 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 S1756232AbeFOOcu (ORCPT ); Fri, 15 Jun 2018 10:32:50 -0400 Received: from us.icdsoft.com ([192.252.146.184]:44820 "EHLO us.icdsoft.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755816AbeFOOct (ORCPT ); Fri, 15 Jun 2018 10:32:49 -0400 X-Greylist: delayed 400 seconds by postgrey-1.27 at vger.kernel.org; Fri, 15 Jun 2018 10:32:48 EDT Received: (qmail 29044 invoked by uid 1001); 15 Jun 2018 14:26:07 -0000 Received: from unknown (HELO ?94.155.37.249?) (famzah@94.155.37.249) by 192.252.159.165 with ESMTPA; 15 Jun 2018 14:26:07 -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> From: Ivan Zahariev Message-ID: <7860105c-553a-534b-57fc-222d931cb972@icdsoft.com> Date: Fri, 15 Jun 2018 17:26:04 +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: <20180614150650.GU1351649@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 On 14.6.2018 г. 18:06 ч., Tejun Heo wrote: > On Thu, Jun 14, 2018 at 02:56:00PM +0300, Ivan Zahariev wrote: >> I posted a kernel bug about this a month ago but it did not receive >> any attention: https://bugzilla.kernel.org/show_bug.cgi?id=199713 >> >> Here is a copy of the bug report and I hope that this is the correct >> place to discuss this: > Well, for now at least, that's the expected behavior. It's not > supposed to be able to account all changes immediately (the kernel > doesn't free a lot of things immediately for performance and other > reasons). The intended use is setting up a reasonable upperbound with > some buffer space. If that's by design, it's a bit disappointing and at least the docs should mention it. The standard RLIMIT_NPROC does not suffer from such accounting discrepancies at any time. The "memory" cgroups controller also does not suffer from any discrepancies -- it accounts memory usage in real time without any lag on process start or exit. The "tasks" file list is also always up-to-date. 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. --Ivan