linux-kernel - Re: [RFC workqueue/driver-core PATCH 4/5] driver core: Use new async_schedule

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Date:   Fri, 28 Sep 2018 10:42:39 -0700
From:   Dan Williams <dan.j.williams@...el.com>
To:     alexander.h.duyck@...ux.intel.com
Cc:     linux-nvdimm <linux-nvdimm@...ts.01.org>,
        Greg KH <gregkh@...uxfoundation.org>,
        Linux-pm mailing list <linux-pm@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Tejun Heo <tj@...nel.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        "Brown, Len" <len.brown@...el.com>,
        Dave Jiang <dave.jiang@...el.com>,
        "Rafael J. Wysocki" <rafael@...nel.org>,
        Vishal L Verma <vishal.l.verma@...el.com>,
        jiangshanlai@...il.com, Pavel Machek <pavel@....cz>,
        zwisler@...nel.org
Subject: Re: [RFC workqueue/driver-core PATCH 4/5] driver core: Use new
 async_schedule_dev command

On Wed, Sep 26, 2018 at 2:52 PM Alexander Duyck
<alexander.h.duyck@...ux.intel.com> wrote:
>
> This change makes it so that we use the device specific version of the
> async_schedule commands to defer various tasks related to devices. By doing
> this we should see a slight improvement in performance as any device that
> is sensitive to latency/locality in the setup will now be initializing on
> the node closest to the device.
>
> Signed-off-by: Alexander Duyck <alexander.h.duyck@...ux.intel.com>
> ---
>  drivers/base/dd.c         |    4 ++--
>  drivers/base/power/main.c |   12 ++++++------
>  2 files changed, 8 insertions(+), 8 deletions(-)
>
> diff --git a/drivers/base/dd.c b/drivers/base/dd.c
> index 5ba366c1cb83..81472dc44a70 100644
> --- a/drivers/base/dd.c
> +++ b/drivers/base/dd.c
> @@ -826,7 +826,7 @@ static int __device_attach(struct device *dev, bool allow_async)
>                          */
>                         dev_dbg(dev, "scheduling asynchronous probe\n");
>                         get_device(dev);
> -                       async_schedule(__device_attach_async_helper, dev);
> +                       async_schedule_dev(__device_attach_async_helper, dev);
>                 } else {
>                         pm_request_idle(dev);
>                 }
> @@ -927,7 +927,7 @@ static int __driver_attach(struct device *dev, void *data)
>                 if (!dev->driver) {
>                         get_device(dev);
>                         dev_set_drvdata(dev, drv);
> -                       async_schedule(__driver_attach_async_helper, dev);
> +                       async_schedule_dev(__driver_attach_async_helper, dev);
>                 }

Above looks good to me...

>                 device_unlock(dev);
>                 return 0;
> diff --git a/drivers/base/power/main.c b/drivers/base/power/main.c
> index 3f68e2919dc5..8495d9b1e9d0 100644
> --- a/drivers/base/power/main.c
> +++ b/drivers/base/power/main.c

Let's split these changes into their own patch, just in case it causes
a suspend regression we can revert it independently of the async
probing change. It might also be worthwhile to have a positive
indication that this improves the latency of power transitions.