Re: [PATCH 0/7] De-couple sysfs memory directories from memory sections

Re: [PATCH 0/7] De-couple sysfs memory directories from memory sections

[Bodo Eggert]

Nathan Fontenot <nfont@austin.ibm.com> wrote:

> The file 'split' allows for splitting the
> directory in two, with each new directory covering half as many
> memory sections as the previous directory.

Just some random thoughts:

1) Why is it needed/helpful?
2) If it is needed, why not take an int to split after n entries?

Re: [PATCH 0/7] De-couple sysfs memory directories from memory sections

[Nathan Fontenot]

On 07/12/2010 02:30 PM, Bodo Eggert wrote:
> Nathan Fontenot <nfont@austin.ibm.com> wrote:
> 
>> The file 'split' allows for splitting the
>> directory in two, with each new directory covering half as many
>> memory sections as the previous directory.
> 
> Just some random thoughts:
> 1) Why is it needed/helpful?

This is needed if someone needed to perform an action (add/remove) a
single memory section. The 'split' option allows users to isolate
a memory section  so these operations could be performed.

> 2) If it is needed, why not take an int to split after n entries?

The idea of being able to split a directory came out of a previous
discussion on how to resolve the issue this patch set is trying to solve.
I included the split functionality in this patch set since it
was suggested.  I will leave the decision of whether or not this
functionality is needed up to the community.

-Nathan 

[PATCH 0/7] De-couple sysfs memory directories from memory sections

[Nathan Fontenot]

This set of patches de-couples the idea that there is a single
directory in sysfs for each memory section.  The intent of the
patches is to reduce the number of sysfs directories created to
resolve a boot-time performance issue.  On very large systems
boot time are getting very long (as seen on powerpc hardware)
due to the enormous number of sysfs directories being created.
On a system with 1 TB of memory we create ~63,000 directories.
For even larger systems boot times are being measured in hours.

This set of patches allows for each directory created in sysfs
to cover more than one memory section.  The default behavior for
sysfs directory creation is the same, in that each directory
represents a single memory section.  This update also adds to
new files to each sysfs memory directory.  The file 'end_phys_index'
contains the physical id of the last memory section covered by
the directory.  The file 'split' allows for splitting the 
directory in two, with each new directory covering half as many
memory sections as the previous directory.

Thanks,

Nathan Fontenot

Re: [PATCH 0/7] De-couple sysfs memory directories from memory sections

[Greg KH]

On Mon, Jul 12, 2010 at 10:27:02AM -0500, Nathan Fontenot wrote:
> This set of patches de-couples the idea that there is a single
> directory in sysfs for each memory section.

Any reason you didn't cc: the sysfs maintainer on these patches?  If
not, I'll gladly ignore them...

(hint, scripts/get_maintainer.pl is your friend...)

greg k-h

Re: [PATCH 0/7] De-couple sysfs memory directories from memory sections

[Nathan Fontenot]

On 07/16/2010 02:13 AM, Greg KH wrote:
> On Mon, Jul 12, 2010 at 10:27:02AM -0500, Nathan Fontenot wrote:
>> This set of patches de-couples the idea that there is a single
>> directory in sysfs for each memory section.
> 
> Any reason you didn't cc: the sysfs maintainer on these patches?  If
> not, I'll gladly ignore them...

Ummm.... I have no good excuse. :)

Will add you to cc for v3 of the patch.

> 
> (hint, scripts/get_maintainer.pl is your friend...)
Thanks.

-Nathan
> 
> greg k-h