Re: [Xen-devel] [PATCH] xen: document balloon driver sysfs files

[Daniel Kiper <dkiper@xxxxxxxxxxxx>]

On Tue, Nov 08, 2011 at 11:59:15AM -0500, Konrad Rzeszutek Wilk wrote:
> On Wed, Oct 26, 2011 at 09:12:12PM +0200, Daniel Kiper wrote:
> > On Wed, Oct 26, 2011 at 11:57:43AM +0100, David Vrabel wrote:
> > > From: David Vrabel <david.vrabel@xxxxxxxxxx>
> > >
> > > Add ABI documentation for the balloon driver's sysfs files.
> > >
> > > Signed-off-by: David Vrabel <david.vrabel@xxxxxxxxxx>
> > > ---
> > >  .../ABI/stable/sysfs-devices-system-xen_memory     |   72 
> > > ++++++++++++++++++++
> > >  1 files changed, 72 insertions(+), 0 deletions(-)
> > >  create mode 100644 
> > > Documentation/ABI/stable/sysfs-devices-system-xen_memory
> > >
> > > diff --git a/Documentation/ABI/stable/sysfs-devices-system-xen_memory 
> > > b/Documentation/ABI/stable/sysfs-devices-system-xen_memory
> > > new file mode 100644
> > > index 0000000..4fbc446
> > > --- /dev/null
> > > +++ b/Documentation/ABI/stable/sysfs-devices-system-xen_memory
> > > @@ -0,0 +1,72 @@
> > > +What:            
> > > /sys/devices/system/xen_memory/xen_memory0/max_retry_count
> > > +Date:            April 2008
> >
> > May 2011
> >
> > > +KernelVersion:   2.6.26
> >
> > 2.6.39, git commit 95d2ac4a0c904942a4fecf815781ebd4171e7a30
> > and 40095de1f9082f058970b985a96d2fbef43f94f4.
> >
> > Additionally, I think it is worth to add default value and special
> > cases description (e.g. max_retry_count == 0 => RETRY_UNLIMITED).
> > Please look into drivers/xen/{balloon.c,xen-balloon.c}
> > and include/xen/balloon.h for details.
> >
> > > +Contact: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
> > > +Description:
> > > +         The maximum number of times the balloon driver will
> > > +         attempt to increase the balloon before giving up.  See
> > > +         also 'retry_count' below.
> > > +
> > > +What:            
> > > /sys/devices/system/xen_memory/xen_memory0/max_schedule_delay
> > > +Date:            April 2008
> >
> > Ditto.
> >
> > > +KernelVersion:   2.6.26
> >
> > Ditto.
> >
> > > +Contact: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
> > > +Description:
> > > +         The limit that 'schedule_delay' (see below) will be
> > > +         increased to.
> > > +
> > > +What:            /sys/devices/system/xen_memory/xen_memory0/retry_count
> > > +Date:            April 2008
> >
> > Ditto.
> >
> > > +KernelVersion:   2.6.26
> >
> > Ditto.
> >
> > > +Contact: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
> > > +Description:
> > > +         The current number of times that the balloon driver
> > > +         has attempted to increase the size of the balloon.
> > > +
> > > +What:            
> > > /sys/devices/system/xen_memory/xen_memory0/schedule_delay
> > > +Date:            April 2008
> >
> > Ditto.
> >
> > > +KernelVersion:   2.6.26
> >
> > Ditto.
> >
> > Daniel
>
> Daniel, how does this look ? I added your Reviewed-by, but if you want
> to make some more modifications I can certainly do so.

Thanks for correcting that. I think that I have found
only one small issue. Please look below.

> >From d759668b660f111b6f35b632031eaf1a136a22f3 Mon Sep 17 00:00:00 2001
> From: David Vrabel <david.vrabel@xxxxxxxxxx>
> Date: Wed, 26 Oct 2011 11:57:43 +0100
> Subject: [PATCH] xen: document balloon driver sysfs files
>
> Add ABI documentation for the balloon driver's sysfs files.
>
> Signed-off-by: David Vrabel <david.vrabel@xxxxxxxxxx>
> Reviewed-by: Daniel Kiper <dkiper@xxxxxxxxxxxx>
> [v2: Added comments from Daniel]
> Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
> ---
>  .../ABI/stable/sysfs-devices-system-xen_memory     |   77 
> ++++++++++++++++++++
>  1 files changed, 77 insertions(+), 0 deletions(-)
>  create mode 100644 Documentation/ABI/stable/sysfs-devices-system-xen_memory
>
> diff --git a/Documentation/ABI/stable/sysfs-devices-system-xen_memory 
> b/Documentation/ABI/stable/sysfs-devices-system-xen_memory
> new file mode 100644
> index 0000000..39463d0
> --- /dev/null
> +++ b/Documentation/ABI/stable/sysfs-devices-system-xen_memory
> @@ -0,0 +1,77 @@
> +What:                
> /sys/devices/system/xen_memory/xen_memory0/max_retry_count
> +Date:                May 2011
> +KernelVersion:       2.6.39
> +Contact:     Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
> +Description:
> +             The maximum number of times the balloon driver will
> +             attempt to increase the balloon before giving up.  See
> +             also 'retry_count' below.
> +             A value of zero means retry forever and is the default one.
> +
> +What:                
> /sys/devices/system/xen_memory/xen_memory0/max_schedule_delay
> +Date:                May 2011
> +KernelVersion:       2.6.39
> +Contact:     Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
> +Description:
> +             The limit that 'schedule_delay' (see below) will be
> +             increased to. The default value is 32.
> +
> +What:                /sys/devices/system/xen_memory/xen_memory0/retry_count
> +Date:                May 2011
> +KernelVersion:       2.6.39
> +Contact:     Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
> +Description:
> +             The current number of times that the balloon driver
> +             has attempted to increase the size of the balloon.
> +             The default value is one. With max_retry_count being
> +             zero (unlimited), this means that the driver will attempt
> +             to retry with a 'schedule_delay' delay.
> +
> +What:                
> /sys/devices/system/xen_memory/xen_memory0/schedule_delay
> +Date:                May 2011
> +KernelVersion:       2.6.39
> +Contact:     Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
> +Description:
> +             The time (in jiffies) to wait between attempts to

It is in seconds. Please look at the end of balloon_process() funtion.
This value is multiplicated by HZ constant (which indeed is scaled in
jiffies, however, I think in this case second is better unit).

Daniel

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