All of lore.kernel.org
 help / color / mirror / Atom feed
From: "Rafael J. Wysocki" <rafael@kernel.org>
To: Keith Busch <kbusch@kernel.org>
Cc: Sagi Grimberg <sagi@grimberg.me>, Christoph Hellwig <hch@lst.de>,
	Len Brown <lenb@kernel.org>, Linux PM <linux-pm@vger.kernel.org>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	m.heingbecker@googlemail.com,
	linux-nvme <linux-nvme@lists.infradead.org>
Subject: [Bug] nvme blocks PC10 since v5.15 - bisected
Date: Fri, 21 Jan 2022 20:00:49 +0100	[thread overview]
Message-ID: <CAJZ5v0hvvYedSn5u-i7sjpoEHU4P65t7i1b2pVn=S1q0nHWgqQ@mail.gmail.com> (raw)

Hi Keith,

It is reported that the following commit

commit e5ad96f388b765fe6b52f64f37e910c0ba4f3de7
Author: Keith Busch <kbusch@kernel.org>
Date:   Tue Jul 27 09:40:44 2021 -0700

   nvme-pci: disable hmb on idle suspend

   An idle suspend may or may not disable host memory access from devices
   placed in low power mode. Either way, it should always be safe to
   disable the host memory buffer prior to entering the low power mode, and
   this should also always be faster than a full device shutdown.

   Signed-off-by: Keith Busch <kbusch@kernel.org>
   Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
   Signed-off-by: Christoph Hellwig <hch@lst.de>

is the source of a serious power regression occurring since 5.15
(please see https://bugzilla.kernel.org/show_bug.cgi?id=215467).

After this commit, the SoC on the affected system cannot enter
C-states deeper than PC2 while suspended to idle which basically
defeats the purpose of suspending.

What may be happening is that nvme_disable_prepare_reset() that is not
called any more in the ndev->nr_host_mem_descs case somehow causes the
LTR of the device to change to "no requirement" which allows deeper
C-states to be entered.

Can you have a look at this, please?

Cheers,
Rafael

             reply	other threads:[~2022-01-21 19:01 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-01-21 19:00 Rafael J. Wysocki [this message]
2022-01-21 21:09 ` [Bug] nvme blocks PC10 since v5.15 - bisected Keith Busch
2022-01-27 19:02   ` Rafael J. Wysocki
2022-01-27 19:30     ` Keith Busch
2022-01-27 19:41       ` Rafael J. Wysocki
2022-02-10 14:56     ` Keith Busch
2022-02-10 18:24       ` Christoph Hellwig
2022-02-10 18:54         ` Jonathan Derrick
2022-02-10 18:54         ` Keith Busch

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to='CAJZ5v0hvvYedSn5u-i7sjpoEHU4P65t7i1b2pVn=S1q0nHWgqQ@mail.gmail.com' \
    --to=rafael@kernel.org \
    --cc=hch@lst.de \
    --cc=kbusch@kernel.org \
    --cc=lenb@kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-nvme@lists.infradead.org \
    --cc=linux-pm@vger.kernel.org \
    --cc=m.heingbecker@googlemail.com \
    --cc=sagi@grimberg.me \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body. 
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.