Hi, On Thu, Jun 16, 2011 at 06:12:51PM +0900, KAMEZAWA Hiroyuki wrote: > On Thu, 16 Jun 2011 09:50:44 +0530 > Ankita Garg <ankita@xxxxxxxxxx> wrote: > > > Hi, > > > > 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 > > challenge > > But it will be required for your purpose, anyway. Isn't it ? > > > - Memory hotplug is a heavy operation, so the overhead involved may be > > high > > 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. > But sections do not define the granualarity at which memory operations are done right ? i.e, allocations/deallocations or reclaim cannot be directed to a section or a group of sections ? -- Regards, Ankita Garg (ankita@xxxxxxxxxx) Linux Technology Center IBM India Systems & Technology Labs, Bangalore, India -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>