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=-2.3 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS,T_DKIMWL_WL_MED, URIBL_BLOCKED,USER_AGENT_MUTT 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 D9575ECDFB1 for ; Fri, 13 Jul 2018 22:11:26 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 832EB2084E for ; Fri, 13 Jul 2018 22:11:26 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=cmpxchg-org.20150623.gappssmtp.com header.i=@cmpxchg-org.20150623.gappssmtp.com header.b="sQxoz6Mk" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 832EB2084E Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=cmpxchg.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 S1732707AbeGMW14 (ORCPT ); Fri, 13 Jul 2018 18:27:56 -0400 Received: from mail-yw0-f193.google.com ([209.85.161.193]:41782 "EHLO mail-yw0-f193.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731935AbeGMW14 (ORCPT ); Fri, 13 Jul 2018 18:27:56 -0400 Received: by mail-yw0-f193.google.com with SMTP id q129-v6so9497098ywg.8 for ; Fri, 13 Jul 2018 15:11:23 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=cmpxchg-org.20150623.gappssmtp.com; s=20150623; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to:user-agent; bh=7PgyzSNJ2bqfKN8F6PdixT1ZQ9Zdxvkc+fOPVFGcypE=; b=sQxoz6MkrCfzDoTQIGPLrKd4xVZIMBDrFsvmmbmc+kAXLuPFVzlBm5DjzRN15UUcP+ D7v/yop7r0jW80AiPLdBdouqkREe6MC+FUAQJ4gfG0ZakjNWam5rQa0H5Y7FH2RuwHH6 s5s7RZkRnpgIG7TuhiZhNE3q/4Y2z0J9iDU9ihUo5g4GXwZCWKCxjBnYuRTEE2ypCC/i RIANcG9WiWGFY9p6utjE8yzYIxvUz1vpALUKT3z5Sps64dBwKb6oxhuMU2uWTsHkl+ed b4XL+3azzT4UCDcQ60eOhDO0R2cSNk0SWITJ1ctbRX4y+0OPC3Oq9ilN8F67S2O5SNkd cYww== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to:user-agent; bh=7PgyzSNJ2bqfKN8F6PdixT1ZQ9Zdxvkc+fOPVFGcypE=; b=S/208LqIVxOhPkjdKot8FDjcO/mN2RTrCGs2/Gh8TbR7x3eeRxVqguEMkOJ4YB7lWh nF9V9N3+Br/hcPa5DXu29aPEy5ugjEGaw7xxGvPdneMI+JGpyQdsaGWY4DYSDWP7z+qv 5SAdXZYPCbJmUKznyOJTLBl+fJs4ssS9lO9ONFiNDBJsZolLqys01EEhFt/8nrdXhf4Y UzemBCQk9t8t0Eqin9I8xYZQzVDhqw/vW32ScVgWH/jFOD2b/knoxcr1Efb2sqcbVxaA WdKXNnVfg9yHQgBSfWntQbSZ1LrcVh9XeeJ+W0ZuIXFPI5+wAvQ/vsEvBxUXe32oIfCU bVDw== X-Gm-Message-State: AOUpUlHJe9eQNOQaP7EW1/EF+maFDcIZr7KuRUj1FxTRCKZLEH920W8Z dH9Htjo50fz/m5TGtBYkI9H4Vw== X-Google-Smtp-Source: AAOMgpf6OFLMtuM3GudZL3CJhIr8Srya+y2URed93alFwwv4BxfbTBdNEq8av4fRO+NJba3B7NFlrw== X-Received: by 2002:a81:160c:: with SMTP id 12-v6mr4207053yww.254.1531519883181; Fri, 13 Jul 2018 15:11:23 -0700 (PDT) Received: from localhost ([2620:10d:c091:180::1:23bd]) by smtp.gmail.com with ESMTPSA id d189-v6sm10476114ywh.93.2018.07.13.15.11.22 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Fri, 13 Jul 2018 15:11:22 -0700 (PDT) Date: Fri, 13 Jul 2018 18:14:06 -0400 From: Johannes Weiner To: Andrew Morton 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: [PATCH 0/10] psi: pressure stall information for CPU, memory, and IO v2 Message-ID: <20180713221042.GA30013@cmpxchg.org> References: <20180712172942.10094-1-hannes@cmpxchg.org> <20180712164422.a53cc0f9c26b078dbc7e5731@linux-foundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180712164422.a53cc0f9c26b078dbc7e5731@linux-foundation.org> User-Agent: Mutt/1.10.0 (2018-05-17) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Jul 12, 2018 at 04:44:22PM -0700, Andrew Morton wrote: > On Thu, 12 Jul 2018 13:29:32 -0400 Johannes Weiner wrote: > > > > > ... > > > > The io file is similar to memory. Because the block layer doesn't have > > a concept of hardware contention right now (how much longer is my IO > > request taking due to other tasks?), it reports CPU potential lost on > > all IO delays, not just the potential lost due to competition. > > Probably dumb question: disks aren't the only form of IO. Does it make > sense to accumulate PSI for other forms of IO? Networking comes to > mind... It's conceivable, although I haven't thought too much about it yet. If that turns out to be a state we might want to track, we can easily add a task state to identify such stalls and add /proc/pressure/net e.g. "io" in this case means only the block layer / filesystems. I think keeping this distinction makes sense in the interest of identifying which type of hardware resource is posing a pressure problem.