Re: [RFC 2/2] x86_64, mm: Reinsert the absent memory

["H. Peter Anvin" <hpa@zytor.com>]

On 06/25/2013 10:22 AM, Mike Travis wrote:
> 
> On 6/25/2013 12:38 AM, Ingo Molnar wrote:
>>
>> * Nathan Zimmer <nzimmer@sgi.com> wrote:
>>
>>> On Sun, Jun 23, 2013 at 11:28:40AM +0200, Ingo Molnar wrote:
>>>>
>>>> That's 4.5 GB/sec initialization speed - that feels a bit slow and the 
>>>> boot time effect should be felt on smaller 'a couple of gigabytes' 
>>>> desktop boxes as well. Do we know exactly where the 2 hours of boot 
>>>> time on a 32 TB system is spent?
>>>
>>> There are other several spots that could be improved on a large system 
>>> but memory initialization is by far the biggest.
>>
>> My feeling is that deferred/on-demand initialization triggered from the 
>> buddy allocator is the better long term solution.
> 
> I haven't caught up with all of Nathan's changes yet (just
> got back from vacation), but there was an option to either
> start the memory insertion on boot, or trigger it later
> using the /sys/.../memory interface.  There is also a monitor
> program that calculates the memory insertion rate.  This was
> extremely useful to determine how changes in the kernel
> affected the rate.
> 

Sorry, I *totally* did not follow that comment.  It seemed like a
complete non-sequitur?

	-hpa