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,SPF_PASS,URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id D13A3ECDFAA for ; Thu, 12 Jul 2018 23:45:41 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 8671120BF2 for ; Thu, 12 Jul 2018 23:45:41 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 8671120BF2 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=linux-foundation.org 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 S2387719AbeGLX5b (ORCPT ); Thu, 12 Jul 2018 19:57:31 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:55338 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2387612AbeGLX5b (ORCPT ); Thu, 12 Jul 2018 19:57:31 -0400 Received: from localhost.localdomain (c-24-4-125-7.hsd1.ca.comcast.net [24.4.125.7]) by mail.linuxfoundation.org (Postfix) with ESMTPSA id A0380DA7; Thu, 12 Jul 2018 23:45:38 +0000 (UTC) Date: Thu, 12 Jul 2018 16:45:37 -0700 From: Andrew Morton To: Johannes Weiner Cc: Ingo Molnar , Peter Zijlstra , Linus Torvalds , Tejun Heo , Suren Baghdasaryan , Vinayak Menon , Christopher Lameter , Mike Galbraith , Shakeel Butt , linux-mm@kvack.org, cgroups@vger.kernel.org, linux-kernel@vger.kernel.org, kernel-team@fb.com Subject: Re: [RFC PATCH 10/10] psi: aggregate ongoing stall events when somebody reads pressure Message-Id: <20180712164537.324caee21fd68c47a02af009@linux-foundation.org> In-Reply-To: <20180712172942.10094-11-hannes@cmpxchg.org> References: <20180712172942.10094-1-hannes@cmpxchg.org> <20180712172942.10094-11-hannes@cmpxchg.org> X-Mailer: Sylpheed 3.5.1 (GTK+ 2.24.31; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 12 Jul 2018 13:29:42 -0400 Johannes Weiner wrote: > Right now, psi reports pressure and stall times of already concluded > stall events. For most use cases this is current enough, but certain > highly latency-sensitive applications, like the Android OOM killer, > might want to know about and react to stall states before they have > even concluded (e.g. a prolonged reclaim cycle). > > This patches the procfs/cgroupfs interface such that when the pressure > metrics are read, the current per-cpu states, if any, are taken into > account as well. > > Any ongoing states are concluded, their time snapshotted, and then > restarted. This requires holding the rq lock to avoid corruption. It > could use some form of rq lock ratelimiting or avoidance. > > Requested-by: Suren Baghdasaryan > Not-yet-signed-off-by: Johannes Weiner What-does-that-mean:?