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 - Memory hotplug is a heavy operation, so the overhead involved may be high - 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 -- 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@xxxxxxxxxx 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>