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From: Keith Busch <kbusch@kernel.org>
To: "Rafael J. Wysocki" <rjw@rjwysocki.net>
Cc: "Busch, Keith" <keith.busch@intel.com>,
	Christoph Hellwig <hch@lst.de>, Sagi Grimberg <sagi@grimberg.me>,
	"linux-nvme@lists.infradead.org" <linux-nvme@lists.infradead.org>,
	Mario Limonciello <Mario.Limonciello@dell.com>,
	Kai Heng Feng <kai.heng.feng@canonical.com>,
	Linux PM <linux-pm@vger.kernel.org>,
	LKML <linux-kernel@vger.kernel.org>
Subject: Re: [Regression] Commit "nvme/pci: Use host managed power state for suspend" has problems
Date: Thu, 25 Jul 2019 08:52:10 -0600	[thread overview]
Message-ID: <20190725145209.GA6949@localhost.localdomain> (raw)
In-Reply-To: <2332799.izEFUvJP67@kreacher>

On Thu, Jul 25, 2019 at 02:51:41AM -0700, Rafael J. Wysocki wrote:
> Hi Keith,
> 
> Unfortunately,
> 
> commit d916b1be94b6dc8d293abed2451f3062f6af7551
> Author: Keith Busch <keith.busch@intel.com>
> Date:   Thu May 23 09:27:35 2019 -0600
> 
>     nvme-pci: use host managed power state for suspend
> 
> doesn't universally improve things.  In fact, in some cases it makes things worse.
> 
> For example, on the Dell XPS13 9380 I have here it prevents the processor package
> from reaching idle states deeper than PC2 in suspend-to-idle (which, of course, also
> prevents the SoC from reaching any kind of S0ix).
> 
> That can be readily explained too.  Namely, with the commit above the NVMe device
> stays in D0 over suspend/resume, so the root port it is connected to also has to stay in
> D0 and that "blocks" package C-states deeper than PC2.
> 
> In order for the root port to be able to go to D3, the device connected to it also needs
> to go into D3, so it looks like (at least on this particular machine, but maybe in
> general), both D3 and the NVMe-specific PM are needed.
> 
> I'm not sure what to do here, because evidently there are systems where that commit
> helps.  I was thinking about adding a module option allowing the user to override the
> default behavior which in turn should be compatible with 5.2 and earlier kernels.

Darn, that's too bad. I don't think we can improve one thing at the
expense of another, so unless we find an acceptable criteria to select
what low power mode to use, I would be inclined to support a revert or
a kernel option to default to the previous behavior.

One thing we might check before using NVMe power states is if the lowest
PS is non-operational with MP below some threshold. What does your device
report for:

  nvme id-ctrl /dev/nvme0

?

  parent reply	other threads:[~2019-07-25 14:55 UTC|newest]

Thread overview: 75+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-07-25  9:51 Rafael J. Wysocki
2019-07-25 14:02 ` Kai-Heng Feng
2019-07-25 16:23   ` Mario.Limonciello
2019-07-25 17:03     ` Rafael J. Wysocki
2019-07-25 17:23       ` Mario.Limonciello
2019-07-25 18:20       ` Kai-Heng Feng
2019-07-25 19:09         ` Mario.Limonciello
2019-07-30 10:45       ` Rafael J. Wysocki
2019-07-30 14:41         ` Keith Busch
2019-07-30 17:14           ` Mario.Limonciello
2019-07-30 18:50             ` Kai-Heng Feng
2019-07-30 19:19               ` Keith Busch
2019-07-30 21:05                 ` Mario.Limonciello
2019-07-30 21:31                   ` Keith Busch
2019-07-31 21:25                     ` Rafael J. Wysocki
2019-07-31 22:19                       ` Keith Busch
2019-07-31 22:33                         ` Rafael J. Wysocki
2019-08-01  9:05                           ` Kai-Heng Feng
2019-08-01 17:29                             ` Rafael J. Wysocki
2019-08-01 19:05                               ` Mario.Limonciello
2019-08-01 22:26                                 ` Rafael J. Wysocki
2019-08-02 10:55                                   ` Kai-Heng Feng
2019-08-02 11:04                                     ` Rafael J. Wysocki
2019-08-05 19:13                                       ` Kai-Heng Feng
2019-08-05 21:28                                         ` Rafael J. Wysocki
2019-08-06 14:02                                           ` Mario.Limonciello
2019-08-06 15:00                                             ` Rafael J. Wysocki
2019-08-07 10:29                                               ` Rafael J. Wysocki
2019-08-01 20:22                             ` Keith Busch
2019-08-07  9:48                         ` Rafael J. Wysocki
2019-08-07 10:45                           ` Christoph Hellwig
2019-08-07 10:54                             ` Rafael J. Wysocki
2019-08-07  9:53                         ` [PATCH] nvme-pci: Do not prevent PCI bus-level PM from being used Rafael J. Wysocki
2019-08-07 10:14                           ` Rafael J. Wysocki
2019-08-07 10:43                           ` Christoph Hellwig
2019-08-07 14:37                           ` Keith Busch
2019-08-08  8:36                         ` [PATCH] nvme-pci: Allow PCI bus-level PM to be used if ASPM is disabled Rafael J. Wysocki
2019-08-08  8:48                           ` Christoph Hellwig
2019-08-08  9:06                             ` Rafael J. Wysocki
2019-08-08 10:03                         ` [PATCH v2 0/2] " Rafael J. Wysocki
2019-08-08 10:06                           ` [PATCH v2 1/2] PCI: PCIe: ASPM: Introduce pcie_aspm_enabled_mask() Rafael J. Wysocki
2019-08-08 13:15                             ` Bjorn Helgaas
2019-08-08 14:48                               ` Rafael J. Wysocki
2019-08-08 10:10                           ` [PATCH v2 2/2] nvme-pci: Allow PCI bus-level PM to be used if ASPM is disabled Rafael J. Wysocki
2019-08-08 13:43                             ` Bjorn Helgaas
2019-08-08 14:47                               ` Rafael J. Wysocki
2019-08-08 17:06                                 ` Rafael J. Wysocki
2019-08-08 18:39                                 ` Bjorn Helgaas
2019-08-08 20:01                                   ` Keith Busch
2019-08-08 20:05                                   ` Mario.Limonciello
2019-08-08 20:41                                   ` Rafael J. Wysocki
2019-08-09  4:47                                     ` Bjorn Helgaas
2019-08-09  8:04                                       ` Rafael J. Wysocki
2019-08-08 21:51                         ` [PATCH v3 0/2] " Rafael J. Wysocki
2019-08-08 21:55                           ` [PATCH v3 1/2] PCI: PCIe: ASPM: Introduce pcie_aspm_enabled() Rafael J. Wysocki
2019-08-09  4:50                             ` Bjorn Helgaas
2019-08-09  8:00                               ` Rafael J. Wysocki
2019-10-07 22:34                             ` Bjorn Helgaas
2019-10-08  9:27                               ` Rafael J. Wysocki
2019-10-08 21:16                                 ` Bjorn Helgaas
2019-10-08 22:54                                   ` Rafael J. Wysocki
2019-10-09 12:49                                     ` Bjorn Helgaas
2019-08-08 21:58                           ` [PATCH v3 2/2] nvme-pci: Allow PCI bus-level PM to be used if ASPM is disabled Rafael J. Wysocki
2019-08-08 22:13                           ` [PATCH v3 0/2] " Keith Busch
2019-08-09  8:05                             ` Rafael J. Wysocki
2019-08-09 14:52                               ` Keith Busch
2019-07-25 16:59   ` [Regression] Commit "nvme/pci: Use host managed power state for suspend" has problems Rafael J. Wysocki
2019-07-25 14:52 ` Keith Busch [this message]
2019-07-25 19:48   ` Rafael J. Wysocki
2019-07-25 19:52     ` Keith Busch
2019-07-25 20:02       ` Rafael J. Wysocki
2019-07-26 14:02         ` Kai-Heng Feng
2019-07-27 12:55           ` Rafael J. Wysocki
2019-07-29 15:51             ` Mario.Limonciello
2019-07-29 22:05               ` Rafael J. Wysocki

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