From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ivan Zahariev Subject: Re: Cgroups "pids" controller does not update "pids.current" count immediately Date: Fri, 15 Jun 2018 19:07:27 +0300 Message-ID: <1d635d1d-6152-ecfc-d235-147ff1fe7c95@icdsoft.com> 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> Mime-Version: 1.0 Content-Transfer-Encoding: 8bit Return-path: In-Reply-To: <20180615154140.GV1351649@devbig577.frc2.facebook.com> Content-Language: en-bg Sender: linux-kernel-owner@vger.kernel.org List-ID: Content-Type: text/plain; charset="utf-8"; format="flowed" To: Tejun Heo Cc: cgroups@vger.kernel.org, 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 --