On Thu, 8 Nov 2012 22:01:33 +0000 KY Srinivasan <kys@xxxxxxxxxxxxx> wrote: > > > > -----Original Message----- > > From: David Rientjes [mailto:rientjes@xxxxxxxxxx] > > Sent: Monday, November 05, 2012 5:33 PM > > To: KY Srinivasan > > Cc: Andrew Morton; Greg KH; olaf@xxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; > > andi@xxxxxxxxxxxxxx; apw@xxxxxxxxxxxxx; devel@xxxxxxxxxxxxxxxxxxxxxx; linux- > > mm@xxxxxxxxx; Hiroyuki Kamezawa; Michal Hocko; Johannes Weiner; Ying Han > > Subject: RE: [PATCH 1/2] mm: Export vm_committed_as > > > > On Mon, 5 Nov 2012, KY Srinivasan wrote: > > > > > The Hyper-V host has a policy engine for managing available physical memory > > across > > > competing virtual machines. This policy decision is based on a number of > > parameters > > > including the memory pressure reported by the guest. Currently, the pressure > > calculation is > > > based on the memory commitment made by the guest. From what I can tell, > > the ratio of > > > currently allocated physical memory to the current memory commitment made > > by the guest > > > (vm_committed_as) is used as one of the parameters in making the memory > > balancing decision on > > > the host. This is what Windows guests report to the host. So, I need some > > measure of memory > > > commitments made by the Linux guest. This is the reason I want export > > vm_committed_as. > > > > > > > I don't think you should export the symbol itself to modules but rather a > > helper function that returns s64 that just wraps > > percpu_counter_read_positive() which your driver could use instead. > > > > (And why percpu_counter_read_positive() returns a signed type is a > > mystery.) > > Yes, this makes sense. I just want to access (read) this metric. Andrew, if you are willing to > take this patch, I could send one. Sure. I suppose that's better, although any module which modifies committed_as would never pass review (rofl). -- 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/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>