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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 21EF3C433EF for ; Wed, 11 May 2022 21:02:24 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237461AbiEKVCX (ORCPT ); Wed, 11 May 2022 17:02:23 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:36910 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S238891AbiEKVCV (ORCPT ); Wed, 11 May 2022 17:02:21 -0400 Received: from mail-io1-xd31.google.com (mail-io1-xd31.google.com [IPv6:2607:f8b0:4864:20::d31]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 383E06161E for ; Wed, 11 May 2022 14:02:20 -0700 (PDT) Received: by mail-io1-xd31.google.com with SMTP id s23so3334666iog.13 for ; Wed, 11 May 2022 14:02:20 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=t9KxxV9NPaarLjUn6WnSeaJ1unQjijG7pUlU5QRc31c=; b=H+FMOTettN+fuJtHKZqvo9EElI2NN1SPK4306s/OFHXEpdYb2w8lMqMB9SYcHYzNYK fPb27VOOqwfpDDqp5639NElcCyMRqOxbTyvlNIvswSaV2AJihPzGq1xo3mRDRoBbdY9Z ieamvJCGxKnz7laf6bu3Els3to1eswUjqz7BPVzm8ZEFjlu+mFmArNAeeZ61qgI+39xf jp6z/bpGJfGdnhddB5JrTTHjNlonTnbTOU1XAcwGupZCq+QMV5rdjheyamVoOumzLFj6 uChw2lg4VDkyw1fMCaQlWP3tiyel2InlZRfoUFjbHjqsH2+sUFi5PugWTKBosWZmIjeT dhLQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=t9KxxV9NPaarLjUn6WnSeaJ1unQjijG7pUlU5QRc31c=; b=aHYfZYm3amz5GrOATqr+URPpadB5P91UE/et+5Ad5UH7df/iL1Sj/16dli52zgFO8B F9z99+NIWnvxhXqiqTFid9fbOxvCW2Fe+HoFoe+GXosw+2n/oDBlcskF8xI+QVuXHpJF uhgSVIVeLnvaRT5Pe8H36Q5nvvwx8tBzNiJFxz3DUGmZl6UW+ExdsZbMmn2kXHuwPmhI r3CituSfS2cl6PIKK7uEjgJD/I6nWrj8V0yWEOMo1adfR+WUdKQurEMXvEoZYy7hAjKW YTWms3C6hgbDmd4yqdjhP4Bfp5oLaC7xBAhuD1jU4394Zp77SdRSfcQVy0YY/B20TtHN X3ug== X-Gm-Message-State: AOAM533/BpZk/gn2iCE2Kn2IGsrRtfL9C9Z7fpT/QuMCf1fmq/0QZx6s ch13ccqF0KSWfRdxJ5ECidOVADkgUs54XCbgLfN2ng== X-Google-Smtp-Source: ABdhPJwmnOOxYv5I7CBMV+/A8hb0Ch9gPYppkXgsf55Nobqofhk/HsYU3WHgCMZG16BXcmY0HTddv62MCMTE6GPSIAQ= X-Received: by 2002:a05:6638:34a2:b0:32b:7d4f:8932 with SMTP id t34-20020a05663834a200b0032b7d4f8932mr13504775jal.317.1652302939471; Wed, 11 May 2022 14:02:19 -0700 (PDT) MIME-Version: 1.0 References: <20220412224348.1038613-1-tansuresh@google.com> <20220412224348.1038613-2-tansuresh@google.com> In-Reply-To: From: Tanjore Suresh Date: Wed, 11 May 2022 14:02:08 -0700 Message-ID: Subject: Re: [PATCH v2 1/3] driver core: Support asynchronous driver shutdown To: Greg Kroah-Hartman Cc: "Rafael J. Wysocki" , Christoph Hellwig , Sagi Grimberg , Bjorn Helgaas , Linux Kernel Mailing List , linux-nvme , Linux PCI Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-pci@vger.kernel.org Greg On Mon, May 2, 2022 at 12:13 PM Tanjore Suresh wrote: > > On Sat, Apr 30, 2022 at 12:52 AM Greg Kroah-Hartman > wrote: > > > > A: http://en.wikipedia.org/wiki/Top_post > > Q: Were do I find info about this thing called top-posting? > > A: Because it messes up the order in which people normally read text. > > Q: Why is top-posting such a bad thing? > > A: Top-posting. > > Q: What is the most annoying thing in e-mail? > > > > A: No. > > Q: Should I include quotations after my reply? > > > > http://daringfireball.net/2007/07/on_top > > > > On Fri, Apr 29, 2022 at 11:03:07AM -0700, Tanjore Suresh wrote: > > > Rafael, > > > > > > That is a good observation, however, many of the use cases in data > > > centers (deployment of devices in data centers) do not exploit device > > > power management. Therefore, I'm not sure that is the right way to > > > design this. > > > > Yes it is, enable device power management and use that interface please. > > Devices in data centers should of course be doing the same thing as > > everyone else, as it actually saves real money in power costs. To not > > do so is very odd. > > > > I guess we are intermixing the terminology of device power management > with shutdown. > My second, third reasoning in my previous e-mail, thought it brings > out that difference. Maybe not. > I will try one more time, my thought process on this one. > > This patch is only for shutdown. The shutdown can be done in a system > in various flavors, > (this may include a power being pulled from the system components when > all the devices > are quiescent and it can also be soft shutdown, where power is not > removed from the system, but system > could be attempting a reboot) > > The device power management allows the device to bring down any > devices that may be idle to various power states that > device may support in a selective manner & based on the transition > allowed by the device. Such a transition initiated by > the system can be achieved using the 'dpm' interface for runtime power > management (more for extending laptop battery life). > It can also be exploited for system sleep models (suspend and resume - > where state is preserved and restarted from where it left off > --> More applicable for laptops/desktops). That does not mean data > center devices cannot exploit, but they worry about slight latency > variation in any > I/O initiated to any device. Such power management could introduce > more latency when it transitions from one state to another. > Therefore, the use case is more apt for Laptops, in certain cases > desktops in my opinion or understanding. > > The shutdown entry point has been traditionally different and the > semantics is that the whole system is going down to a > quiescent state and power may be pulled or may not be, IMO, i am > seeing both are independent requirements, in my view. > Let me know if I am mistaken. I am not sure why we should break the > shutdown semantics as understood by driver developers and > overload it with dpm requirements? > I have not seen additional comments, I request your help in moving this further, please. If i have missed something, Please let me know. Thanks sureshtk > Thanks > sureshtk > > > > thanks, > > > > greg k-h