linux-kernel - [PATCH v1 0/3] Asynchronous shutdown interface and example implementation

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Message-Id: <20220328230008.3587975-1-tansuresh@google.com>
Date:   Mon, 28 Mar 2022 16:00:05 -0700
From:   Tanjore Suresh <tansuresh@...gle.com>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        "Rafael J . Wysocki" <rafael@...nel.org>,
        Christoph Hellwig <hch@....de>,
        Sagi Grimberg <sagi@...mberg.me>,
        Bjorn Helgaas <bhelgaas@...gle.com>
Cc:     linux-kernel@...r.kernel.org, linux-nvme@...ts.infradead.org,
        linux-pci@...r.kernel.org, Tanjore Suresh <tansuresh@...gle.com>
Subject: [PATCH v1 0/3] Asynchronous shutdown interface and example implementation

Problem:

Some of our machines are configured with  many NVMe devices and
are validated for strict shutdown time requirements. Each NVMe
device plugged into the system, typicaly takes about 4.5 secs
to shutdown. A system with 16 such NVMe devices will takes
approximately 80 secs to shutdown and go through reboot.

The current shutdown APIs as defined at bus level is defined to be
synchronous. Therefore, more devices are in the system the greater
the time it takes to shutdown. This shutdown time significantly
contributes the machine reboot time.

Solution:

This patch set proposes an asynchronous shutdown interface at bus level,
modifies the core driver, device shutdown routine to exploit the
new interface while maintaining backward compatibility with synchronous
implementation already existing (Patch 1 of 3) and exploits new interface
to enable all PCI-E based devices to use asynchronous interface semantics
if necessary (Patch 2 of 3). The implementation at PCI-E level also works
in a backward compatible way, to allow exiting device implementation
to work with current synchronous semantics. Only show cases an example
implementation for NVMe device to exploit this asynchronous shutdown
interface. (Patch 3 of 3).

Tanjore Suresh (3):
  driver core: Support asynchronous driver shutdown
  PCI: Support asynchronous shutdown
  nvme: Add async shutdown support

 drivers/base/core.c        | 39 ++++++++++++++++++-
 drivers/nvme/host/core.c   | 28 +++++++++----
 drivers/nvme/host/nvme.h   |  8 ++++
 drivers/nvme/host/pci.c    | 80 ++++++++++++++++++++++++--------------
 drivers/pci/pci-driver.c   | 17 ++++++--
 include/linux/device/bus.h | 10 +++++
 include/linux/pci.h        |  2 +
 7 files changed, 144 insertions(+), 40 deletions(-)

-- 
2.35.1.1021.g381101b075-goog