[PATCH 5/5] zram: Set initial disksize to some default value
ngupta at vflare.org
Sat Sep 10 07:51:49 PDT 2011
On 09/09/2011 08:42 PM, Greg KH wrote:
> On Fri, Sep 09, 2011 at 08:18:56PM -0400, Nitin Gupta wrote:
>> On 09/09/2011 07:12 PM, Greg KH wrote:
>>> On Fri, Sep 09, 2011 at 07:01:04PM -0400, Nitin Gupta wrote:
>>>> Currently, we set initial disksize as 0, which forces
>>>> user to write some value to corresponding zram device's
>>>> sysfs node, before the device can be used. Now, we avoid
>>>> this step by providing some default size initially.
>>>> To change the disksize, user must:
>>>> - Reset disk.
>>>> Ex: echo 1 > /sys/block/zram0/reset
>>>> (NOTE: disksize is set to the default value after reset)
>>>> - Set new disksize.
>>>> Ex: echo $((256*1024*1024)) > /sys/block/zram0/disksize
>>> So, what tools just broke with this change?
>>> And where is the sysfs file documentation change that should go along
>>> with this?
>> This change does not change any sysfs names or behavior, so does not
>> break any scripts that assume the current behavior. I also verified that
>> sysfs documentation (ABI/testing/sysfs-block-zram) need not be changed
>> and same with drivers/staging/zram/zram.txt.
> Huh, you just said the behavior changed as described in your comment
> above. You said the user no longer has to do a step to accomplish
> something. What happens if they do do that after this patch?
The current documentation states that:
"" (from drivers/staging/zram/zram.txt)
2) Set Disksize (Optional):
Set disk size by writing the value to sysfs node 'disksize'
(in bytes). If disksize is not given, default value of 25%
of RAM is used.
So existing code did not correctly implement this behavior -- user had
to set a disksize for zram to be usable. With this patch, the code now
behaves exactly as described in documentation. So, we now avoid the
extra step of setting a disksize as documented. The user can still, of
course, set another disk value if needed.
So, in summary, no documentation changes are required with this change.
I will also add this explanation in changelog when submitting v4 patches.
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