[PATCH] docs: improve the description of --size in the man page of zramctl

[PATCH] docs: improve the description of --size in the man page of zramctl

[Benno Schulenberg]

Signed-off-by: Benno Schulenberg <bensberg@justemail.net>
---
 sys-utils/zramctl.8 |   13 ++++---------
 1 files changed, 4 insertions(+), 9 deletions(-)

diff --git a/sys-utils/zramctl.8 b/sys-utils/zramctl.8
index a308233..6f82ccf 100644
--- a/sys-utils/zramctl.8
+++ b/sys-utils/zramctl.8
@@ -67,15 +67,10 @@ Reset the options of the specified zram device(s).  Zram device settings
 can be changed only after a reset.
 .TP
 .BR \-s , " \-\-size " \fIsize
-Force the zram driver to reread the size of the file associated with
-the specified zram device.  When not specified the
-.I size
-unit is bytes.  The zram devices size is page size aligned.  When
-requested
-.I size
-does match with page size the device be large enough to hold the reqested
-.I size
-plus length to next page boundary.
+Create a zram device of the specified \fIsize\fR.
+Zram devices are aligned to memory pages; when the requested \fIsize\fR is
+not a multiple of the page size, it will be rounded up to the next multiple.
+When not otherwise specified, the unit of the \fIsize\fR parameter is bytes.
 .IP
 The \fIsize\fR argument may be followed by the multiplicative suffixes KiB (=1024),
 MiB (=1024*1024), and so on for GiB, TiB, PiB, EiB, ZiB and YiB (the "iB"
-- 
1.7.0.4

Re: [PATCH] docs: improve the description of --size in the man page of zramctl

[Benno Schulenberg]

On Mon, Aug 11, 2014, at 22:23, Benno Schulenberg wrote:
> The zram devices size is page size aligned.  When
> -requested
> -.I size
> -does match with page size the device be large enough to hold the reqested
> -.I size
> -plus length to next page boundary.

The above does not parse for me.  I am not in a position to test
zram devices, so to be sure that my replacement text is correct,
the following question: when one passes with --size a number that
is not a multiple of the memory-page size, does a subsequent call
of 'zramctl --raw' then print the aligned (rounded-up) number, or
does it still print the size that was specified although in fact
the aligned, bigger number is being used?

Benno

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Re: [PATCH] docs: improve the description of --size in the man page of zramctl

[Karel Zak]

On Mon, Aug 11, 2014 at 10:34:04PM +0200, Benno Schulenberg wrote:
> 
> On Mon, Aug 11, 2014, at 22:23, Benno Schulenberg wrote:
> > The zram devices size is page size aligned.  When
> > -requested
> > -.I size
> > -does match with page size the device be large enough to hold the reqested
> > -.I size
> > -plus length to next page boundary.
> 
> The above does not parse for me.  I am not in a position to test
> zram devices, so to be sure that my replacement text is correct,

  # modprobe zram 

  # ./zramctl --find --size $((4096 * 1000 + 100 ))
  /dev/zram0

  # echo $(( 4096 * 1000 + 100))
  4096100
  
  # ./zramctl --bytes -n -o DISKSIZE
  4100096


> the following question: when one passes with --size a number that
> is not a multiple of the memory-page size, does a subsequent call
> of 'zramctl --raw' then print the aligned (rounded-up) number, or
> does it still print the size that was specified although in fact
> the aligned, bigger number is being used?

 The kernel uses the aligned $size and nowhere is stored the original
 size, so zramctl returns the aligned (rounded-up) number.

    Karel

-- 
 Karel Zak  <kzak@redhat.com>
 http://karelzak.blogspot.com

Re: [PATCH] docs: improve the description of --size in the man page of zramctl

[Benno Schulenberg]

On Tue, Aug 12, 2014, at 14:37, Karel Zak wrote:
>  The kernel uses the aligned $size and nowhere is stored the original
>  size, so zramctl returns the aligned (rounded-up) number.

Okay.  Then my replacement text is valid.

Benno

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Re: [PATCH] docs: improve the description of --size in the man page of zramctl

[Karel Zak]

On Mon, Aug 11, 2014 at 10:23:39PM +0200, Benno Schulenberg wrote:
>  sys-utils/zramctl.8 |   13 ++++---------
>  1 files changed, 4 insertions(+), 9 deletions(-)

 Applied, thanks.

-- 
 Karel Zak  <kzak@redhat.com>
 http://karelzak.blogspot.com