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=-0.9 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS autolearn=no 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 7C87EC2D0C6 for ; Thu, 12 Dec 2019 01:50:20 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 524C220652 for ; Thu, 12 Dec 2019 01:50:20 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1576115420; bh=6ua+gFrFHp8Ic5JviapLkNfyb1mlSo4I1NxW0GbS5aE=; h=References:In-Reply-To:From:Date:Subject:To:Cc:List-ID:From; b=Tj6pzfEaU25Ht4sYnpmJdEdePMJllHNoVPZd04slt7qZYA3QxKWoYci6zI2gBZ8/b vm3bTzE1O9uDU6rseYTHZMec1IKqAfRdEkddxJ5fjw3Bz9yoU3DFEakKdh806l1LBr +ObX5BTkDUjEBgS0/0GpC7w1g7zItJQDlLoGznII= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727544AbfLLBuT (ORCPT ); Wed, 11 Dec 2019 20:50:19 -0500 Received: from mail-lj1-f194.google.com ([209.85.208.194]:36851 "EHLO mail-lj1-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727543AbfLLBuS (ORCPT ); Wed, 11 Dec 2019 20:50:18 -0500 Received: by mail-lj1-f194.google.com with SMTP id r19so374816ljg.3 for ; Wed, 11 Dec 2019 17:50:16 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux-foundation.org; s=google; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=PC+SlnRf7svTDlkNpHBVMSNitoLO6r2vdwDHMDAkNI8=; b=fNkGcKXQB3xCtLQKXADqQ3G/djHPEEOB2trqYHHu5gTxMrHq7l42M/wCwdjLYpZmt5 d7A+P6Xe/uSH2xY8H4UU5n/Z0u0+D6EAJztG7SF9hKLTZUlA4KZhCzbYrxxykxZ762O1 5fT3K/zxq8wXmuG9+5Iondt19rtNqXTpw1zSg= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=PC+SlnRf7svTDlkNpHBVMSNitoLO6r2vdwDHMDAkNI8=; b=m0EVfsVC4Jj5yw9ZQyTN7dlYD0cOW3VEiDrLTbkI23fFmzKmThKjture00mj6ioWsr +dEywCsKy4F6zj4f25CkXR24Ha66lmGmQsVaqruscpy47Y3HwJV1IibI4+q6uPoCON8w +dVc04BwNXRsDPy7lSF7Qxljxhh5F/mOCo9FPamprt5qnBxYxKVv1ieC1I4b2pCyaMOZ B5+8Cjp8XpX9t3WWt5CDVPQq6wHUwJAHrVkO4EGWVPWuuNnXu5yL0SZeEJjhyy7gklko kxwK7JYqgJECWEY4nUohSbTWcmUffYjtrxFf15wFzh7ENaae2rAGXqE154/D/G7ZvOQ2 cDKg== X-Gm-Message-State: APjAAAWzupuFAuCqzrmSDT0yY38ZkBmzVJArMHt70jEk/SRg3jQnLTBm woWXcaFslPv61LXRNg7782YS1johurc= X-Google-Smtp-Source: APXvYqzWewWSxd+yk2RI4alibIC89tM8SMoDYT3i0zmwsTw+kx9LZ0UfHeU/ZL1TC2NsEH7ETw7rMQ== X-Received: by 2002:a2e:7f08:: with SMTP id a8mr4058070ljd.164.1576115414913; Wed, 11 Dec 2019 17:50:14 -0800 (PST) Received: from mail-lj1-f176.google.com (mail-lj1-f176.google.com. [209.85.208.176]) by smtp.gmail.com with ESMTPSA id z26sm2010088lfq.69.2019.12.11.17.50.13 for (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 11 Dec 2019 17:50:13 -0800 (PST) Received: by mail-lj1-f176.google.com with SMTP id k8so366030ljh.5 for ; Wed, 11 Dec 2019 17:50:13 -0800 (PST) X-Received: by 2002:a2e:9ad8:: with SMTP id p24mr4244948ljj.148.1576115413333; Wed, 11 Dec 2019 17:50:13 -0800 (PST) MIME-Version: 1.0 References: <20191211152943.2933-1-axboe@kernel.dk> <0d4e3954-c467-30a7-5a8e-7c4180275533@kernel.dk> <1c93194a-ed91-c3aa-deb5-a3394805defb@kernel.dk> <6e2ca035-0e06-1def-5ea9-90a7466b2d49@kernel.dk> In-Reply-To: <6e2ca035-0e06-1def-5ea9-90a7466b2d49@kernel.dk> From: Linus Torvalds Date: Wed, 11 Dec 2019 17:49:57 -0800 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [PATCHSET v3 0/5] Support for RWF_UNCACHED To: Jens Axboe Cc: Linux-MM , linux-fsdevel , linux-block , Matthew Wilcox , Chris Mason , Dave Chinner , Johannes Weiner Content-Type: text/plain; charset="UTF-8" Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org On Wed, Dec 11, 2019 at 5:41 PM Jens Axboe wrote: > > So now I'm even more puzzled why your (desktop?) doesn't show it, it > must be more potent than my x1 laptop. But for me, the laptop and 2 > socket test box show EXACTLY the same behavior, laptop is just too slow > to make it really pathological. I see the exact same thing. And now, go do "perf record -a sleep 100" while this is going on, to see the big picture. Suddenly that number is a lot smaller. Because the kswapd cost is less than 10% of one cpu, and the xas_create is 30% of that. IOW, it's not all that dominant until you zoom in on it. Considering the amount of IO going on, it's kind of understandable. But as mentioned, it does look like something that should be fixed. Maybe it's even something where it's a bad XArray case? Willy? Linus