Re: [PATCH 00/10] mm: Linux VM Infrastructure to support MemoryPower Management
From: KAMEZAWA Hiroyuki
Date: Thu Jun 16 2011 - 05:19:55 EST
On Thu, 16 Jun 2011 09:50:44 +0530
Ankita Garg <ankita@xxxxxxxxxx> wrote:
> On Mon, Jun 13, 2011 at 01:47:01PM +0900, KAMEZAWA Hiroyuki wrote:
> > On Fri, 27 May 2011 18:01:28 +0530
> > Ankita Garg <ankita@xxxxxxxxxx> wrote:
> > > Hi,
> > >
> > I'm sorry if you've answered already.
> > Is memory hotplug is too bad and cannot be enhanced for this purpose ?
> > I wonder
> > - make section-size smaller (IIUC, IBM's system has 16MB section size)
> > - add per section statistics
> > - add a kind of balloon driver which does software memory offline
> > (which means making a contiguous chunk of free pages of section_size
> > by page migration) in background with regard to memory usage statistics.
> > If system says "need more memory!", balloon driver can online pages.
> > can work for your purpose. It can allow you page isolatation and
> > controls in 16MB unit. If you need whole rework of memory hotplug, I think
> > it's better to rewrite memory hotplug, too.
> Interesting idea, but a few issues -
> - Correctly predicting memory pressure is difficult and thereby being
> able to online the required pages at the right time could be a
But it will be required for your purpose, anyway. Isn't it ?
> - Memory hotplug is a heavy operation, so the overhead involved may be
soft-offline of small amount of pages will not very heavy.
compaction and cma patches use the same kind of logic.
> - Powering off memory is just one of the ways in which memory power could
> be saved. The platform can also dynamically transition areas of memory
> into a content-preserving lower power state if it is not referenced
> for a pre-defined threshold of time. In such a case, we would need a
> mechanism to soft offline the pages - i.e, no new allocations to be
> directed to that memory
Hmm, sounds like a similar idea of CleanCache ?
Reusing section is much easier than adding new one.., I think.
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/