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[23.128.96.18]) by mx.google.com with ESMTP id bo12si8320711edb.430.2020.06.01.08.17.53; Mon, 01 Jun 2020 08:18:18 -0700 (PDT) Received-SPF: pass (google.com: domain of linux-nfs-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18; Authentication-Results: mx.google.com; dkim=pass header.i=@umich.edu header.s=google-2016-06-03 header.b=fKQQxVi6; spf=pass (google.com: domain of linux-nfs-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) smtp.mailfrom=linux-nfs-owner@vger.kernel.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=umich.edu Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726232AbgFAPRv (ORCPT + 99 others); Mon, 1 Jun 2020 11:17:51 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:39546 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726125AbgFAPRv (ORCPT ); Mon, 1 Jun 2020 11:17:51 -0400 Received: from mail-ed1-x52d.google.com (mail-ed1-x52d.google.com [IPv6:2a00:1450:4864:20::52d]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id D6F8DC05BD43 for ; Mon, 1 Jun 2020 08:17:50 -0700 (PDT) Received: by mail-ed1-x52d.google.com with SMTP id k19so7533044edv.9 for ; Mon, 01 Jun 2020 08:17:50 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=umich.edu; s=google-2016-06-03; h=mime-version:from:date:message-id:subject:to; bh=zKxdkmhi3M1rHkXRBR18pioJZURS63Upm912Ufd4mhY=; b=fKQQxVi6RiLcJxETNOwyq5dX91D5GEtkbOXHAHObBMIHHpb18EYuHVg8Wc6ql92354 GbywZeNYEmbKUhE+WU4cFt18/jWbutE3EPOESrWJNfyERzdvRStRMEWJ0XOaIT3+T7v8 yqCNjaAzijITafpzPJ0RQ9iO9gIrkUA6atd/R5YsHgZbkMuakJcqmQIb4AIMtKblkcav URWVeCK5vNztJH2rWytqz7HJkq0Z2uXeTUpXRlWnSuF2FWzhLXnD7WZT9wEHIWzCQU+J u3CyNyFZnU5h/cTZaNFn/8MZm9V3U78W6HHv/3V7uE/749nHiDuiyUqTV8QB4thHTTzI q7DA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:from:date:message-id:subject:to; bh=zKxdkmhi3M1rHkXRBR18pioJZURS63Upm912Ufd4mhY=; b=AbcaFQAsi0az23cMJY+Wq0T7oyKKuY9kyvRDmZeLm/6asLFok+D+qvMf6wzyIDiRgL FTnI4VBZYYBXSHhD78iyUjVyTP7Gmt23v5gHFerj1YI37wElJCFEdfJXKSIpKZqSCajA JqCJid7FLvwYbFsQHXic8631fkezhYO3RQn0DxDn72RqSBpefoDAO+ERe68nfRwCMwgY qMe9sNyL6ucpDz3He1o1Cd3HvV4et5xKCEmGU4YcIOdmsKcuIfqW46o0JiRb+9yR3Wl7 6rwjc292w6ok1HKwlqzjUS6VTLZJ1QDGsSgLUvM0JZMrQDPXfTPMBvOQB9lQ3D52YfJg HFew== X-Gm-Message-State: AOAM532XpkVL/mdVjcRiMqvVzaZiR8gHEMSnWscKE5q5Lk8Z0KSWXBfF FOmjD6CcU0JsA9RlOm/rrx+21jN7TO6cqrjuw7/yoREB X-Received: by 2002:aa7:d650:: with SMTP id v16mr21278605edr.267.1591024669338; Mon, 01 Jun 2020 08:17:49 -0700 (PDT) MIME-Version: 1.0 From: Olga Kornievskaia Date: Mon, 1 Jun 2020 11:17:38 -0400 Message-ID: Subject: understanding why writes get priority over other operations To: linux-nfs Content-Type: text/plain; charset="UTF-8" Sender: linux-nfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-nfs@vger.kernel.org Hi folks, I'm trying to look for an explanation of if this is true and if so why writes gets priority over other operations (like reads)? I see in the code in write.c if FLUSH_HIGHPRI is set in flags then we'll have an RPC marked with high priority. The problem is I don't see anything setting FLUSH_HIGHPRI. I see that writes are written with either FLUSH_STABLE or FLUSH_COND_STABLE (or no flags). Basically I can't see how FLUSH_HIGHPRI is used. If it's not used, then question: does the NFS layer ever priorities writes over other operations? If NFS doesn't then prioritization must be coming from the VM system I'm thinking. Thank you.